INTRODUCTION — Prostate cancer is common and a frequent cause of cancer death. In the United States, prostate cancer is the most commonly diagnosed visceral cancer; in 2011, there were expected to be about 242,000 new prostate cancer diagnoses and about 28,000 prostate cancer deaths [1]. Prostate cancer is second only to nonmelanoma skin cancer and lung cancer as the leading cause of cancer and cancer death, respectively, in US men. Worldwide, in 2008 there were estimated to be 903,000 new cases of prostate cancer and 258,000 prostate cancer deaths making it the second most commonly diagnosed cancer in men and the sixth leading cause of male cancer death [2].
For an American male, the lifetime risk of developing prostate cancer is 16 percent, but the risk of dying of prostate cancer is only 2.9 percent [3]. Many more cases of prostate cancer do not become clinically evident, as indicated in autopsy series, where prostate cancer is detected in one-third of men under the age of 80 and in two-thirds of older men [4]. (See "Risk factors for prostate cancer", section on 'Age'.) These data suggest that prostate cancer often grows so slowly that most men die of other causes before the disease becomes clinically advanced.
Prostate cancer survival is related to many factors, especially the extent of tumor at the time of diagnosis. The five-year relative survival among men with cancer confined to the prostate (localized) or with just regional spread is 100 percent compared with 31.9 percent among those diagnosed with distant metastases [3]. While men with advanced stage disease may benefit from palliative treatment, their tumors are generally not curable.
Thus, a screening program that could identify asymptomatic men with aggressive localized tumors might be expected to substantially reduce prostate cancer morbidity, including urinary obstruction and painful metastases, and mortality.
Prostate-specific antigen (PSA) testing revolutionized prostate cancer screening. Although PSA was originally introduced as a tumor marker to detect cancer recurrence or disease progression following treatment, it became widely adopted for cancer screening by the early 1990s. Subsequently, professional societies issued guidelines supporting prostate cancer screening with PSA [5,6]. PSA testing led to a dramatic increase in the incidence of prostate cancer, peaking in 1992 (figure 1) [7]. The majority of these newly-diagnosed cancers were clinically localized (figure 2), which led to an increase in radical prostatectomy and radiation therapy, aggressive treatments intended to cure these early-stage cancers [8-11].
However, prostate cancer screening has been a controversial issue because decisions were made about adopting PSA testing in the absence of efficacy data from randomized trials [12]. Subsequently, the European Randomized Study of Screening for Prostate Cancer (ERSPC) reported a small absolute survival benefit with PSA screening after nine years of follow-up [13]; however, 48 additional patients would need to be diagnosed with prostate cancer to prevent one prostate cancer death. Although the report did not address quality of life outcomes, considerable data show the potential harms from aggressive treatments, including erectile dysfunction, urinary incontinence, and bowel problems [14]. Further sustaining the uncertainty surrounding screening, a report from the large United States trial, the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, published concurrently with the European trial, found no benefit for annual PSA and digital rectal examination (DRE) screening after 7 to 10 years of follow-up [15].
This topic reviews the screening tests that are available for prostate cancer, the efficacy of screening, and the recommendations of major medical associations and societies regarding screening for prostate cancer. Risk factors and the clinical manifestations and diagnosis of prostate cancer are discussed separately. (See "Risk factors for prostate cancer" and "Clinical presentation, diagnosis, and staging of prostate cancer".)
PROSTATE SPECIFIC ANTIGEN (PSA) — PSA is a glycoprotein produced by prostate epithelial cells. PSA levels may be elevated in men with prostate cancer because PSA production is increased and because tissue barriers between the prostate gland lumen and the capillary are disrupted, releasing more PSA into the serum. (See "Measurement of prostate specific antigen".)
Studies have estimated that PSA elevations can precede clinical disease by 5 to 10 years [16,17] or even longer [18]. However, PSA is also elevated in a number of benign conditions (table 1), particularly benign prostatic hyperplasia (BPH) and prostatitis. (See "Clinical manifestations and diagnosis of benign prostatic hyperplasia" and "Acute and chronic bacterial prostatitis".)
Measuring PSA — In addition to the PSA elevations seen with BPH, there are transient causes of PSA elevation (table 1), some of which are significant enough to affect the performance of PSA measurement as a screening test. We describe PSA values in ng/mL throughout this topic, but this is equivalent to the SI units of mcg/L; that is, 4 ng/mL = 4mcg/L. (See "Measurement of prostate specific antigen", section on 'Causes of an elevated serum PSA'.)
PSA has a half-life of 2.2 days [19], and levels elevated by different benign conditions will have variable recovery times [20-22]. PSA testing should be deferred accordingly:
- Digital rectal examination (DRE) has minimal effect on PSA levels, leading to transient elevations of only 0.26 to 0.4 ng/mL, and PSA can be measured immediately after DRE [23,24].
- Ejaculation can increase PSA levels by up to 0.8 ng/mL, though levels return to normal within 48 hours [25,26]. We do not usually ask men to abstain from sexual activity prior to PSA measurement. However, if an initial measurement is high enough to potentially prompt an intervention (ie, biopsy), but close to a borderline value, it is appropriate to repeat the PSA measurement after having the man abstain from ejaculation for at least 48 hours.
- Bacterial prostatitis may elevate PSA levels [27], but they generally return to baseline six to eight weeks after symptoms resolve. Asymptomatic prostatic inflammation can also elevate PSA levels [28], but this diagnosis is made on biopsy and so cannot generally be used to defer screening tests [27].
- Prostate biopsy may elevate PSA levels by a median of 7.9 ng/mL within 4 to 24 hours following the procedure [20]. Levels will remain elevated for two to four weeks. Similarly, a transurethral resection of the prostate (TURP) can elevate PSA levels by a median of 5.9 ng/mL [20]. Levels will remain elevated for a median time of approximately three weeks. A screening PSA test should not be performed for at least six weeks following either of these procedures.
- Acute urinary retention may elevate PSA levels, but the levels can be expected to decrease by 50 percent within one to two days following resolution. A screening PSA test should not be performed for at least two weeks following an episode of acute urinary retention.
The five-alpha reductase inhibitors finasteride and dutasteride lower PSA levels. Finasteride lowers PSA by a median 50 percent within six months of use, though the effects can vary widely, ranging from –81 percent to +20 percent [29]; dutasteride has been reported to reduce PSA 48 to 57 percent [30]. Some experts recommend doubling the measured PSA value before interpreting the result for patients on finasteride [31]. Longitudinal results from the Prostate Cancer Prevention Trial suggest that PSA values be corrected by a factor of 2 for the first two years of finasteride therapy, and by 2.5 for longer term use [32].
Test performance — Determining the accuracy of PSA testing has been difficult because most men with normal PSA values will not undergo biopsy unless their digital examination is abnormal. This work-up bias tends to overestimate sensitivity and underestimate specificity [33]. Performance can also be overestimated because PSA often detects clinically-unimportant cancers. (See 'Overdiagnosis' below.)
Another problem in assessing the accuracy of PSA is that the transrectal needle biopsy is not a perfect gold standard. Investigators have suggested that the false-negative rate can range from 10 to 20 percent [34,35], though the recent trend towards obtaining 12 samples has increased the detection rate [36,37].
Additionally, protocols that use large numbers of biopsies to evaluate patients with an elevated PSA may be detecting incidental cancers that were not the etiology of the PSA elevation. One review that assumed that nonpalpable cancers smaller than 1.0 cm3 would not cause elevated PSA levels estimated that approximately 25 percent of cancers detected by PSA screening were too small to have accounted for the PSA rise that prompted a biopsy [38].
The diagnostic performance of PSA ideally needs to be calibrated against clinically-important cancers. However, there is no consensus on defining such cancers. Although many experts consider tumors with Gleason scores ≥7 and volumes >0.5 cm3 to have a greater risk for progression, there is no certainty that these cancers will lead to early death or reduce quality of life [39].
Sensitivity and specificity — The traditional cutoff for an abnormal PSA level in the major screening studies has been 4.0 ng/mL [40-43]. The American Cancer Society systematically reviewed the literature assessing PSA performance [44]. In a pooled analysis, the estimated sensitivity of a PSA cutoff of 4.0 ng/mL was 21 percent for detecting any prostate cancer and 51 percent for detecting high-grade cancers (Gleason ≥8). Using a cutoff of 3.0 ng/mL increased these sensitivities to 32 and 68 percent, respectively. The estimated specificity was 91 percent for a PSA cutoff of 4.0 ng/mL and 85 percent for a 3.0 ng/mL cutoff. PSA has poorer discriminating ability in men with symptomatic benign prostatic hyperplasia [45].
Positive predictive value — The test performance statistic that has been best characterized by screening studies is the positive predictive value: the proportion of men with an elevated PSA who have prostate cancer.
Overall, the positive predictive value for a PSA level >4.0 ng/mL is approximately 30 percent, meaning that slightly less than one in three men with an elevated PSA will have prostate cancer detected on biopsy [40,46,47]. For PSA levels between 4.0 to 10.0 ng/mL, the positive predictive value is about 25 percent [46]; this increases to 42 to 64 percent for PSA levels >10 ng/mL [46,48].
However, nearly 75 percent of cancers detected within the "gray zone" of PSA values between 4.0 to 10.0 ng/mL are organ confined and potentially curable [46]. The proportion of organ-confined cancers drops to less than 50 percent for PSA values above 10.0 ng/mL [46]. Thus, detecting the curable cancers in men with PSA levels less than 10.0 ng/mL presents a diagnostic challenge because the high false-positive rate leads to many unnecessary biopsies.
Negative predictive value — The Prostate Cancer Prevention Trial, which biopsied men with normal PSA levels, estimated a negative predictive value of 85 percent for a PSA value ≤4.0 ng/mL [49].
Effect of lowering PSA cutoffs — Some investigators have suggested using a lower PSA cutoff because some men with PSA levels below 4 ng/mL and normal digital rectal examinations are found to have prostate cancer [50-53].
In a subset analysis from the placebo arm of the Prostate Cancer Prevention Trial, 449 of 2950 men (15.2 percent) ages 62 to 91 years who had consistently normal PSA levels and digital rectal examinations during the seven years of annual screening had prostate cancer on an end-of-study biopsy; 67 (2.3 percent) had high-grade prostate cancer with a Gleason score of 7 or higher [49]. Among men with a PSA concentration between 2.1 and 4.0 ng/mL, 24.7 percent had prostate cancer, and 5.2 percent had prostate cancer with a Gleason score of 7 or higher.
These observations indicate that there is not a clear cutpoint between "normal" and "abnormal" PSA levels. The Prostate Cancer Prevention Trial found that for biopsies performed during follow-up in the control group even a PSA cutoff of 1.1 ng/mL would miss 17 percent of cancers, including 5 percent of poorly differentiated cancers [54]. Thus, any choice of PSA cutoff involves a tradeoff between sensitivity and specificity. While lowering the PSA cutoff would improve test sensitivity, a lower PSA cutoff would also reduce specificity, leading to far more false-positive tests and unnecessary biopsies. It has been projected that if the PSA threshold were to be lowered to 2.5 ng/mL, the number of men defined as abnormal would double, to up to six million in the US [55]. Additionally, many of the cancers detected at these lower levels may never have become clinically evident, thereby leading to overdiagnosis and overtreatment [56].
There is also evidence that diagnosing prostate cancer at low PSA levels does not affect outcome. A study of 875 men undergoing radical prostatectomy found only a limited association between preoperative PSA levels of 2 to 9 ng/mL and cure rates [57]. The disease-free survival curves did not significantly diverge until the preoperative PSA levels reached 7 ng/mL, suggesting that diagnosing cancers at a lower PSA level may be unnecessary. Most of the PSA elevation below 7 ng/mL was attributed to benign hyperplastic tissue. The investigators emphasized the need for a better serum marker to identify early-stage aggressive cancers.
Serial PSA measurements — Both detection rates and positive predictive values decline substantially with serial testing [58-61]:
- During four rounds of annual PSA screening in the PLCO trial, the number of cancers detected per 1000 men decreased from 14.2 to 9.3 [60]. Similarly, the positive predictive value of a PSA level >4.0 ng/mL decreased from 44.5 to 34.9 percent.
- The cancer detection rate for PSA in the ERSPC, which used a 4-year screening interval, decreased from 5.1 percent in the first round of screening to 4.4 percent in the second round [61]. The positive predictive value for a PSA level of 3.0 ng/mL or greater decreased from 29.2 to 19.9 percent.
Studies also found that repeated testing increases the likelihood that detected tumors will be clinically organ-confined and be moderately or well differentiated [41,60-62] (see 'Frequency and method of screening' below):
- In the PLCO, the proportion of screening-detected cancers diagnosed at clinical stage I or II increased from 94.2 percent in round one to 98.5 percent in round 2, while the proportion with Gleason scores ≥7 decreased from 10.0 to 6.8 percent [60].
- In the ERSPC, the proportion of clinical stage I and II cancers increased from 81.5 to 96.3 percent, while the proportion of poorly-differentiated cancers decreased from 8.1 to 3.3 percent [61].
Secular trends in the utility of PSA — A United States study that looked at the correlation between PSA level and prostate cancer during five-year intervals at a university hospital found that while serum PSA was correlated with prostate cancer stage, grade, and size in the interval from 1983 to 1988, in the interval from 1998 to 2003 it was correlated only with prostate weight (related to benign prostatic hypertrophy) [63].
The authors concluded that in this era of intense screening for prostate cancer, PSA has ceased to be a useful marker, and biopsies in men with an elevated PSA level are only picking up the background prevalence of prostate cancer [63,64]. That is, the same rates of prostate cancer could be found in men of the same age without regard to PSA level, and in many cases the detected tumors would never become clinically significant (see 'Overdiagnosis' below). The authors point out that a study that performed saturation prostate biopsies in men with negative sextant biopsies also found no significant association between PSA level and prostate cancer [65].
The results of these studies raise further concerns about the utility of PSA as a marker for clinically significant prostate cancer.
Improving the accuracy of PSA — Numerous strategies have been proposed to improve the diagnostic performance of PSA when levels are less than 10.0 ng/mL. These strategies include measuring PSA velocity (change in PSA over time), PSA density (PSA per unit volume of prostate), free PSA, complexed PSA, and using age- and race-specific reference ranges [66]. We suggest not routinely using any of these strategies in deciding which men to refer for biopsy. (See "Measurement of prostate specific antigen".)
PSA velocity — PSA increases more rapidly in men with prostate cancer than in healthy men. The Baltimore Longitudinal Study of Aging (BLSA) found that men with a PSA rate of change (PSA velocity) greater than 0.75 ng/mL/year were at increased risk of being diagnosed with prostate cancer and that PSA velocity was more specific than a 4.0 ng/mL PSA cutoff (90 versus 60 percent specificity) [67]. The study results, though, were based on analyzing the banked serum of only 18 cancer cases. Furthermore, there are significant short-term physiologic variations in the PSA level [68]. Accurately measuring PSA velocity requires three serial readings, ideally with the same assay, obtained over at least a 12- to 24-month period [66,69,70].
However, analyses of more recent clinical data from randomized trials suggest that PSA velocity adds little predictive information to the total PSA:
- The European Randomized Study of Screening for Prostate Cancer (ERSPC) data from Rotterdam found that PSA velocity was significantly higher in men with prostate cancer than in men with a negative biopsy (0.62 versus 0.46 ng/mL/year) [71]. However, PSA velocity did not independently predict cancer after adjusting for PSA level.
Another analysis of pooled ERSPC data from the Netherlands and Sweden similarly found that PSA velocity only slightly improved the predictive accuracy of total PSA (area under the ROC curve 0.57 versus 0.53), but not for detecting high-grade disease [72].
Among the 774 Rotterdam men with a PSA level below 4.0 ng/mL who underwent their first biopsies in the second round of ERSPC, 149 were found to have cancer [73]. PSA velocity did not discriminate between men with cancer and those with negative biopsies. The sensitivity of a PSA velocity cutoff of 0.3 ng/mL/year was only 39 percent, with a false positive rate of 33 percent. - In two separate analyses, the Prostate Cancer Prevention Trial reported on the 5519 men from the placebo group who underwent prostate biopsy following at least two PSA measurements in the preceding two or three years [74,75]. While PSA level was a significant predictor of prostate cancer diagnosis on multivariate modeling, incorporating PSA velocity did not add clinically important predictive information to PSA level alone, particularly for PSA values ≥4.0 ng/mL. When total PSA was less than 4.0 ng/mL and the DRE was normal, a PSA velocity above 0.35 ng/mL/year predicted cancer. However, using velocity would substantially increase the number of unnecessary biopsies while missing more high-grade cancers than would be identified by just lowering the PSA cutoff.
- A systematic review of PSA velocity, including 12 comparisons with total PSA for predicting prostate cancer diagnosis, found numerous methodological limitations and essentially no evidence supporting the use of PSA velocity for clinical decision-making [76].
Some investigators have argued that PSA doubling time or percent change is a more appropriate measure of PSA kinetics [77]. PSA velocity is correlated with the total PSA level, which increases exponentially before clinical diagnosis.
Even though PSA velocity may be independently correlated with cancer diagnosis, it adds little to the diagnostic accuracy of PSA alone [78].
PSA density — The PSA density measurement is based upon the observation that prostate cancers can produce approximately 10 times more PSA per volume of prostate tissue than benign conditions [19,79]. PSA density measurements, which adjust PSA values for prostate volume, have been reported to better discriminate between cancer and noncancer groups than PSA levels alone [80].
However, PSA density measurements require transrectal ultrasound or magnetic resonance imaging to assess prostate volume, which limits applicability in primary care settings. Additionally, precisely estimating prostate volume is difficult [69].
Data from a large multicenter screening trial suggested that using a cutoff PSA density of 0.15 ng/mL/cm3 (a commonly-recommended cutoff value) would miss nearly 50 percent of cancers detected in men with a normal digital rectal examination and PSA levels between 4.0 to 10.0 ng/mL [81]. Adjusting the PSA density cutoff value for total PSA level might improve the test sensitivity [82].
Measuring the PSA density of the prostatic transition zone has also been proposed to improve the specificity of PSA since the hyperplastic tissue that can elevate PSA is almost completely localized to this area of the prostate [66]. Using a PSA transition zone density greater than 0.22 ng/mL/cm3 as a biopsy criterion was estimated to reduce the number of negative biopsies by 24.4 percent based upon data from an Austrian screening study [83]. However, given the logistic difficulties of performing density measurements as well as their lack of reproducibility, the transition zone density is not currently accepted for routine clinical practice [66].
Free PSA — The observation that PSA exists in a free form as well as bound to macromolecules has been used to develop additional assays to improve test specificity. The ratio of free-to-total PSA is reduced in men with prostate cancer. Investigators have proposed that biopsies be performed only in men with lower ratios. A large multicenter, prospective trial evaluated men 50 to 75 years with PSA levels between 4.0 and 10.0 ng/mL, including 379 with prostate cancer and 394 with benign prostate disease [84]. The cancer detection rate for this PSA range in screening populations is about 25 percent [46]. However, the detection rate increased to 56 percent for men with a free-to-total PSA ratio less than 10 percent [84]. The investigators selected an optimal cutoff of 25 percent as a criterion for biopsy, which would have reduced the number of unnecessary biopsies by 20 percent in their study cohort. However, men with a normal free-to-total PSA ratio still had an 8 percent probability of having cancer, which may not be low enough to convince patients and clinicians to forego biopsy. A meta-analysis came to similar conclusions that free-to-total PSA ratio is generally only clinically helpful at extreme values of the ratio [85].
A separate meta-analysis of free PSA noted considerable variability in free PSA assays, specimen handling, cutoffs, and patient populations [86]. The authors concluded that more research was necessary to determine the optimal cutoff and to accurately assess the diagnostic performance and utility of the test in screening populations.
Complexed PSA — Another strategy to improve PSA specificity has been to measure complexed PSA (cPSA). Most circulating PSA is bound to alpha-1-antichymotripsin. A study using archival serum found that, at 95 percent sensitivity, cPSA had a specificity of 26.7 percent compared with 15.6 percent for the free-to-total PSA ratio and 21.8 percent for total PSA [87].
A prospective study in 831 men undergoing prostate biopsy found that cPSA was more specific than total PSA [88]. For men with a total PSA concentration between 4 to 10 ng/mL, when a cPSA cutpoint was chosen to achieve a sensitivity of 90 percent, cPSA had a higher specificity than total PSA (13.3 versus 8.6 percent), but it was less specific than percent free PSA and percent complexed PSA (21.5 and 21.9 percent, respectively). For men with a total PSA concentration between 2 to 6 ng/mL, cPSA was more specific than other methods.
The marginal benefit of measuring complexed PSA over total PSA remains uncertain.
[-2]ProPSA — [-2]ProPSA (also known as p2PSA) is a specific isoform of the PSA proenzyme proPSA. It has been used to increase the detection of prostate cancer for men with PSA values between 2.0 to 10.0 ng/mL. One prospective observational study estimated that using the p2PSA assay (which is not available in the United States) could reduce the number of unnecessary biopsies by 7.6 percent while maintaining a sensitivity of 95 percent for detecting prostate cancer [89]. The cohort included 892 men with normal digital rectal examinations, some of whom previously had negative prostate biopsies. Another prospective study of 268 subjects, using the ratio of p2PSA over free PSA, estimated about a 35 percent reduction in the number of unnecessary biopsies while maintaining 95 percent sensitivity [90]. Neither study presented data on the performance of p2PSA for detecting high-risk cancers. The clinical utility of this biomarker is uncertain [91].
Age-specific reference ranges — PSA levels increase with age, largely due to a higher prevalence of benign prostatic hyperplasia [92]. Although we do not recommend their use, age-specific reference ranges have been developed from normal populations to improve the discriminating power of PSA [93]:
- 40 to 49 years — 0 to 2.5 ng/mL
- 50 to 59 years — 0 to 3.5 ng/mL
- 60 to 69 years — 0 to 4.5 ng/mL
- 70 to 79 years — 0 to 6.5 ng/mL
Raising the PSA biopsy threshold in older men improves specificity, reducing the number of unnecessary biopsies. Conversely, lowering the threshold in younger men improves sensitivity and increases detection of early-stage tumors.
A retrospective analysis of a large screening cohort reported that applying age-specific reference standards would miss 47 percent of clinically localized cancers in men 70 and older and lead to a 45 percent increase in unnecessary biopsies for men in their 50s [94].
The clinical utility of age-specific reference ranges remains uncertain, and they are not recommended by the US Food and Drug Administration (FDA) or PSA assay manufacturers [66].
Race-specific reference ranges — Black men in the United States have the world's highest incidence of prostate cancer and are the most likely to present with advanced stage disease [11]. PSA levels in blacks are higher compared with whites even after adjusting for age, clinical stage, and histology [95]. This difference has been attributed to blacks having larger tumor volumes across all clinical stages.
Although we do not recommend their use, race-specific PSA reference ranges have been established in the hope of achieving earlier diagnosis [96]:
- 40 to 49 years — 0 to 2.5 ng/mL (whites); 0 to 2.0 ng/mL (blacks)
- 50 to 59 years — 0 to 3.5 ng/mL (whites); 0 to 4.0 ng/mL (blacks)
- 60 to 69 years — 0 to 3.5 ng/mL (whites); 0 to 4.5 ng/mL (blacks)
- 70 to 79 years — 0 to 3.5 ng/mL (whites); 0 to 5.5 ng/mL (blacks)
However, a study of 651 men undergoing radical prostatectomy found that the race-specific reference ranges, which raise the cutoff for blacks 50 years and older compared with whites, would be associated with similar or worse outcomes [97]. The clinical utility of the race-specific reference ranges, which have also been developed for Asians [98], remains uncertain.
Summary — There is no consensus on using any of the PSA modifications, and none of them has been shown to reduce the number of unnecessary biopsies or improve clinical outcomes. The total PSA cutoff of 4.0 ng/mL has been the most accepted standard because it balances the tradeoff between missing important cancers at a curable stage and avoiding both detection of clinically insignificant disease and subjecting men to unnecessary prostate biopsies [39,56,66]. Ongoing efforts are targeted at identifying new serum markers that will have greater diagnostic accuracy for prostate cancer, particularly for aggressive tumors [66,99]. (See "Measurement of prostate specific antigen".)
DIGITAL RECTAL EXAMINATION — Digital rectal examination (DRE) has long been used to diagnose prostate cancer. Abnormal prostate findings include nodules, asymmetry, or induration. DRE can detect tumors in the posterior and lateral aspects of the prostate gland; an inherent limitation to the digital examination is that only 85 percent of cancers arise peripherally where they can be detected with a finger examination [100]. Stage T1 cancers are nonpalpable by definition.
No controlled studies have shown a reduction in the morbidity or mortality of prostate cancer when detected by DRE at any age [101]. The majority of cancers detected by digital examination alone are clinically or pathologically advanced [102]. Thus, the greatest value of DRE may be its use in combination with PSA testing. (See 'Combining PSA and DRE' below.)
Test performance — Urologists have been found to have relatively low interrater agreement for detecting prostate abnormalities [103]. No data are available for the test performance characteristics of DRE in primary care.
Approximately 2 to 3 percent of men 50 or more years old who undergo a single DRE have induration, marked asymmetry, or nodularity of the prostate. In one analysis, an abnormal screening DRE doubled the odds of detecting a clinically important cancer (defined as a having a tumor volume greater than 0.5 mL) that was confined to the prostate [48]. Although screening DRE increased the likelihood of finding early disease, it also increased the odds three- to ninefold of finding extraprostatic extension of tumor (presumably not amenable to curative therapy).
Sensitivity and specificity — A meta-analysis of DRE estimated a sensitivity for detecting prostate cancer of 59 percent and a specificity of 94 percent [104].
Positive predictive value — The positive predictive value of an abnormal DRE for prostate cancer varies from 5 to 30 percent [46,102,105-108]. A meta-analysis calculated an overall positive predictive value of 28 percent [104].
COMBINING PSA AND DRE — Prostate specific antigen (PSA) and digital rectal examination (DRE) are somewhat complementary, and their combined use can increase the overall rate of cancer detection [39,46,109-111]. As an example, a multicenter screening study of 6630 men reported a detection rate of 3.2 percent for DRE, 4.6 percent for PSA, and 5.8 percent for the two methods combined [46,106]. PSA detected significantly more of the cancers than digital examination (82 versus 55 percent). Overall, 45 percent of the cancers were detected only by PSA, while just 18 percent were detected solely by digital examination.
Investigators reported a positive predictive value of 10 percent for a suspicious digital examination when the PSA level was normal. However, the positive predictive value was 24 percent for an elevated PSA level with a normal digital examination. Among men with a normal PSA level, abnormalities on DRE appear less likely to be from a cancer if the PSA concentration is below 1.0 ng/mL than if the PSA concentration is between 3.0 to 4.0 ng/mL [108].
Although these data suggest a potential benefit for combining PSA and DRE in detecting prostate cancer, randomized trials have not confirmed a benefit on prostate cancer outcomes. The ERSPC, which found a small survival benefit with PSA screening, did not consistently require DRE [13]. The PLCO found no survival benefit with combined PSA and DRE screening [15].
OTHER TESTS
PCA3 — The prostate cancer antigen 3 gene (PCA3), which was identified in 1999, is highly overexpressed in almost all prostate cancer tissue specimens, but not in normal or hypertrophied tissue [112]. A PCA3 score, based on the ratio of PCA3 mRNA over PSA mRNA (which is not related to serum PSA levels or cancer), can be determined from a urine specimen collected after a vigorous digital rectal examination. PCA3 has been evaluated for guiding biopsy decisions when PSA levels are in an indeterminate range (2.5 to 10.0 ng/mL) and for men with previously negative biopsies but persistently elevated PSA levels.
A 2010 review identified 11 clinical trials, representing 2737 subjects, evaluating the diagnostic performance of PCA3 [113]:
- In four studies evaluating patients with indeterminate PSA, sensitivity ranged from 53 to 84 percent and specificity ranged from 71 to 80 percent.
- In three studies with at least 200 patients that provided data on PCA3 performance following a previous negative biopsy, sensitivity ranged from 47 to 58 percent, and specificity ranged from 71 to 72 percent. PCA3 outperformed PSA and percent free PSA in independently predicting a positive biopsy.
However, determining the clinical utility of PCA3 from these studies is difficult. Aside from the relatively small sample sizes, studies differed in their criteria for biopsy referral (PSA levels 2.5 to 3.0 ng/mL, digital rectal examination findings, or risk factors), the generation of the PCA3 test used, and the cutpoint for defining an abnormal test. Additionally, none of the studies used PCA3 scores as an indication for biopsy.
The Rotterdam site of the ERSPC subsequently reported the results of using PCA3 as an initial screening test, with sextant biopsy performed if either the PSA level was ≥3 or the PCA3 score was ≥10 [114]. Based on receiver operating characteristic (ROC) curve analysis of 721 subjects undergoing biopsy, PCA3 performed only marginally better than total PSA (area under the curve 0.64 versus 0.58, p = 0.14); PCA3 also missed the majority of cancers with Gleason >6 or stage ≥T2a, though only 19 men met these criteria. However, the generalizability of these results is uncertain because all subjects had already undergone three rounds of screening, and 29 percent had previous negative biopsies.
While PCA3 may eventually have a role in reducing unnecessary biopsies, there are insufficient data on clinical outcomes to currently support routine use.
Transrectal ultrasonography — Transrectal ultrasonography (TRUS) is an outpatient procedure that requires no sedation or analgesia and is relatively well tolerated by most men.
TRUS is not recommended as a primary screening test for prostate cancer because of its low sensitivity and positive predictive value. As an example, in one study almost 40 percent of cancers would have been missed if prostate biopsies had been performed only in men with suspicious findings on TRUS [46]. Furthermore, TRUS is not a feasible screening test in primary care clinics. TRUS is typically used to guide prostate biopsy rather than as a screening test.
EFFECTIVENESS OF PROSTATE CANCER SCREENING — Apart from issues of cost and acceptability, in order for prostate cancer screening to be valuable, it must reduce disease-specific morbidity and/or mortality.
Evidence from randomized trials — Two well-designed large randomized trials have evaluated the effectiveness of screening for prostate cancer and found somewhat differing results:
- In the European Randomized Study of Screening for Prostate Cancer (ERSPC), 182,160 men between the ages of 50 and 74 were randomly assigned to PSA screening (an average of once every four years) or a control group that was not offered screening [13]. This study used different recruiting and randomization procedures across seven centers in Europe. The study used PSA cutoffs between 2.5 and 4.0 ng/mL (most centers used a cutoff of 3.0 ng/mL) as indications for referral for biopsy, variably supplemented with DRE, transrectal ultrasonography, and/or measurements of free PSA levels. The overall rate of prostate cancer screening in the control group was not reported, though 31 percent of cancers were categorized as stage T1c (diagnosed based on elevated PSA level). Investigators subsequently reported PSA testing among 24 percent of the Rotterdam site controls and estimated that 50 percent of the tests were for screening [115].
After a median follow-up of 11 years, for the 162,243 men between the ages of 55 and 69 the primary outcome of prostate cancer mortality was 21 percent lower in the group offered screening (rate ratio 0.79, 95% CI 0.68-0.91) [116]. The absolute rates of prostate cancer mortality were 0.39 versus 0.50 per 1000 person-years (absolute reduction of 0.10 deaths per 1000 person-years; 1055 men needed to be invited for screening to prevent one prostate cancer death over 11 years). Prostate cancer was diagnosed more frequently in the screening group (9.7 versus 6.0 cases per 1000 person-years), such that 37 additional cases of prostate cancer would need to be detected by screening to prevent one death from prostate cancer over 11 years. All-cause mortality was not reduced with screening (18.2 versus 18.5 deaths per 1000 person-years; rate ratio 0.99, CI 0.97-1.01). Several centers collected quality-of-life data; however, these results have not yet been published.
Although the absolute mortality benefit for screening was low, several factors could have biased the results toward no effect. About 24 percent of subjects invited for screening did not undergo PSA testing [13]. While not definitively characterized, a substantial proportion of the control group likely received PSA testing (31 percent of cancers were screening-detected). A subsequent analysis of the Rotterdam site data used patient surveys and linkages with a central national laboratory to estimate contamination. Adjusting for contamination and non-adherence with screening, investigators estimated that prostate cancer screening could reduce prostate cancer mortality by as much as 31 percent (95% CI 8-49 percent) [117]. Additionally, at least 25 percent of cancers detected in the screening group did not receive curative treatment with either surgery or radiation. Finally, given the indolent course of prostate cancer and the five to ten year lead time associated with PSA testing, follow-up duration may have been insufficient to accurately estimate the survival benefit. A modeling study using data from all ERSPC sites concluded that the screening benefit could increase over time, with numbers needed to screen of 837 at year 10 and 503 at year 12 [118]. However, any survival benefit from screening would not be realized for many years, while the burdens of screening and treatment, including harms from overdiagnosis and overtreatment, would occur immediately and potentially have lifelong consequences.
Several biases could also have favored the screening group [119]. A higher proportion of cancers diagnosed in the screening group were aggressively treated (surgery or radiation) compared to the control group, so some of the outcome differences could be related more to improved treatment than screening. Additionally, the committee adjudicating cause of death was aware of cancer treatments. Previous studies have suggested that cause of death is less likely to be attributed to prostate cancer for patients who received aggressive treatment [120]. The ERSPC investigators did not report the association of cancer death and receipt of treatment.
The ERSPC site from Göteborg, Sweden subsequently reported a cumulative mortality reduction of 44 percent for the PSA screening group after a median 14 years of follow up [121]. The Göteborg site, which used population registries to randomly allocate men to either the screening or control groups, could plausibly be more likely to demonstrate benefit than the other ERSCP sites because it offered screening every two years (versus every four years) and the median follow up was 5 years longer than for the initial report. Additionally, the Göteborg results were based on a cohort of men ages 50 to 64, compared to ages 55 to 69 in the combined ERSPC report. This suggests that screening may be less beneficial for men 65 and older, consistent with the finding that radical prostatectomy did not confer a survival benefit compared to watchful waiting for men in this age range [122]. Nevertheless, the 95 percent confidence interval for mortality reduction ranged from 18 to 61 percent, which overlaps the overall 20 percent risk reduction previously reported by ERSPC, and the absolute cumulative risk reduction was only 0.40 percent (95% CI 0.17-0.64%). Screening also increased the risk for prostate cancer diagnosis by 55 percent. Finally, men in the screening group were more likely to receive attempted curative therapy than those in the control group, particularly radical prostatectomy. - In the United States Prostate, Lung, Colorectal and Ovarian Cancer (PLCO) Screening Trial, 76,693 men between the ages of 55 and 74 were randomly assigned to annual screening with PSA and DRE or to usual care [15]. A PSA level above 4.0 ng/mL or an abnormal DRE were indications for biopsy. A high proportion of men in the control group underwent PSA testing (52 percent in the sixth year of the study) and over 40 percent of study subjects had undergone PSA testing within three years before enrolling in the trial.
In contrast to the ERSPC, after seven years of follow-up there was no reduction in the primary outcome of prostate cancer mortality (50 versus 44 deaths in the screening and control groups, respectively; rate ratio 1.13, 95% CI 0.75-1.70). Cancer detection in the screening group was significantly higher than in the control group (2820 versus 2322, rate ratio 1.22, CI 1.16-1.29). A subsequent publication looking at longer-term follow-up within the PLCO (92 percent follow-up through 10 years; 57 percent through 13 years) found similar prostate cancer mortality results (RR 1.12, CI 1.07-1.17) with no suggestion of reduced mortality in the patients followed for 13 years (RR 1.09, CI 0.87-1.36) [123]. This suggests that the differences in results between the ERSPC and the PLCO were not related to the duration of follow-up. Additionally, the investigators found no evidence that screening could be beneficial in any subgroups defined by comorbidity, age, or pretrial PSA testing.
The negative results could be attributable to the high rate of PSA testing in the control arm, the high proportion of subjects with recent PSA testing at baseline (because serial testing is associated with finding fewer and less aggressive cancers), the higher PSA cutoff for biopsy compared with that used in the ERSPC, or the small number of prostate cancer deaths. An earlier PLCO publication also indicated that substantial proportions of men with abnormal PSA and/or DRE results had not undergone biopsy within three years following the positive screen [60]. All of these factors could bias the PLCO trial toward a null result, and also suggest that further follow-up is not likely to yield positive results.
One earlier randomized trial of screening for prostate cancer reported positive findings, but the data analysis was flawed. In this population-based study in Quebec, 46,193 men aged 45 to 80 years identified from electoral records were randomly assigned to screening with prostate specific antigen (PSA) and digital rectal examination (DRE) versus no screening [58]. In an analysis that excluded the 77 percent of men in the screening arm who declined screening and excluded the 6.5 percent of men in the control group who were screened, the prostate cancer mortality rate in men undergoing screening was reported to be 67.1 percent lower than in the control group. When the data were evaluated by a more appropriate intention-to-screen analysis, there were no mortality differences between the two groups (4.6 versus 4.8 deaths per 1000 persons, respectively). Additionally, the results suggesting benefit seemed biologically implausible, since the survival benefit became apparent within only three years, a very short time for a screening program to be effective given the long lead time for prostate cancer.
A 2010 meta-analysis summarized results from six randomized trials (including unique data from two ERSPC sites), with a total of 387,286 participants [124]. Screening with PSA with or without DRE compared to no screening did not reduce death from prostate cancer (relative risk [RR] 0.88, 95% CI 0.71-1.09). However, screening significantly increased the probability of cancer diagnosis (RR 1.46, CI 1.21-1.77). In a 2011 Cochrane meta-analysis that had similar findings, the estimated prostate cancer-specific mortality difference was not statistically significant (RR 0.95, 95% CI 0.85-1.07), but cancer was diagnosed significantly more often in men randomized to screening (RR 1.35, 95% CI 1.06-1.72) [125].
Evidence from observational studies — Before publication of the randomized trials, other data had been cited to support the effectiveness of screening. Given the conflicting results discussed above, observational studies provide information that can fill in some gaps in evidence from the trials.
Over the past decade, Surveillance Epidemiology and End Results (SEER) tumor registry data have shown a significant decline in the incidence of advanced stage disease, potentially consistent with effective screening [126]. Prostate cancer mortality rates, which initially increased following the advent of PSA testing, have now declined to pre-PSA levels (figure 1) [126].
These mortality trends, however, are difficult to interpret. Some ecologic data suggest an association between PSA testing and declining mortality rates:
- In Austria, the state of Tyrol introduced mass screening in 1993. Within five years, investigators observed a more than threefold adjusted decrease in prostate cancer mortality rates in Tyrol compared with the rest of the country where screening was less common [127].
- Data from Olmsted County in Minnesota demonstrated that age-adjusted 1993 to 1997 prostate cancer mortality rates declined 22 percent (95% CI –49 to 17) compared with rates measured in years before PSA testing [128].
- A study found that age-adjusted prostate cancer mortality peaked in the early 1990s in both the United States and the United Kingdom, but then declined much faster in the US, where PSA screening became common, than in the UK, where PSA screening was less common (yearly decline -4.2 versus -1.1 percent) [129].
However, other ecologic studies have shown declining mortality rates even in the absence of intensive screening:
- Trends in prostate cancer mortality rates in Wales and England from 1991 to 1997 were comparable to trends in the United States. Mortality rates declined by 1.7 percent in the United Kingdom, even though PSA screening was not routinely performed and even discouraged [130].
Regional practice variation has allowed investigators to evaluate the effect of screening and treatment on prostate cancer mortality within the United States:
- Medicare beneficiaries in Seattle received more intensive PSA screening and aggressive cancer treatment from 1987 to 1990 than beneficiaries in Connecticut. However, there were no differences in prostate cancer-specific mortality over 11 years of follow-up; the adjusted mortality rate ratio was 1.03 (95% CI 0.95-1.11) in Seattle compared with Connecticut [131].
Alternative explanations have been proposed for declining mortality rates:
- Better treatment could also reduce mortality rates, particularly androgen deprivation therapy for men with advanced-stage cancer. These treatments could allow men to survive long enough to die from a comorbid condition.
- Some experts have argued that the curious mortality trends observed in the PSA era (an initial rise and subsequent decline that paralleled the incidence trends) could also be explained by attribution bias [132]. This bias occurs when deaths are incorrectly attributed to prostate cancer in men whose deaths were actually caused by another disease. If a fixed proportion of deaths in people known to have prostate cancer are consistently misattributed to prostate cancer, then the mortality rates would follow the rising and falling incidence of cancer in the population, as was observed in the 1990s.
Case-control studies have also examined the relationship between screening and prostate cancer outcomes. A large nested case-control study found no evidence that PSA screening for prostate cancer reduces all-cause mortality (odds ratio 1.08, 95% CI 0.71-1.64) [133]. Two other case-control studies found no significant reduction in prostate-cancer mortality with PSA screening (odds ratio 1.19 (95% CI 0.76 - 1.60)) [134] or the combination of PSA and DRE screening (odds ratio 0.70, 95% CI 0.46, 1.1) [135]. However, another case-control study found that screening was associated with a decreased risk of metastatic prostate cancer [136]. Methodologic differences may explain these conflicting results [137].
Evidence from modeling studies — Simulation models using data from Surveillance Epidemiology and End Results (SEER) registries suggest that PSA screening could account for 45 to 70 percent of the observed decline in prostate cancer mortality rates, mainly by decreasing the incidence of distant stage disease [138]. However, treatment advancements may have also contributed to the declining mortality rates.
HARM FROM SCREENING
Risks of biopsy — Although early reports indicated that prostate biopsies very rarely (<1 percent) caused complications (eg, bleeding, infection) serious enough to require hospitalization [139], an analysis of Medicare data found higher hospitalization rates in more recent years for complications (particularly infectious) in the 30 days following biopsy [140]. The authors hypothesized that this could be due to increased number of biopsy cores and antimicrobial resistance. The procedure can also lead to anxiety and physical discomfort [141]. Among 116 men undergoing biopsy in the Rotterdam screening study, 55 percent reported discomfort with the procedure, including 2 percent who had pain persisting longer than one week.
Being diagnosed with prostate cancer is psychologically distressing, but even patients with a negative biopsy result may be distressed [142,143]. Chronic anxiety can follow a negative prostate biopsy because this apparently favorable result cannot completely rule out prostate cancer given the relatively high false-negative biopsy rate [144].
Overdiagnosis — Overdiagnosis refers to the detection by screening of conditions that would not have become clinically significant. When screening finds cancer that would never have become clinically significant, patients are subject to the risks of screening, confirmatory diagnosis, and treatment, as well as suffering potential psychosocial harm from anxiety and labeling. Overdiagnosis is of particular concern because most men with screening-detected prostate cancers have early-stage disease and will be offered aggressive treatment.
A number of reports have raised concerns about the risk of overdiagnosis with screening:
- While the lifetime risk of being diagnosed with prostate cancer has increased from 1 in 11 to 1 in 6, the lifetime risk of dying from prostate cancer has remained around 1 in 34 following the advent of PSA testing [3].
- Although about 80 percent of detected cancers are considered clinically important based on tumor size and grade [145], these are relatively crude prognostic markers. Autopsy series in men who died from other causes have shown a 30 to 45 percent prevalence of prostate cancer in men in their fifties and an 80 percent prevalence in men in their seventies [146-148].
- A study that applied computer-simulation models of PSA testing to SEER cancer incidence data estimated that 29 percent of cancers detected in whites and 44 percent of cancers detected in blacks were overdiagnosed [149]. An updated analysis, that also used ERSPC Rotterdam clinical data, estimated an overdiagnosis fraction ranging from 23 to 42 percent among cancers diagnosed by PSA screening [150].
- Similarly, a study that applied simulation models to the results of the ERSPC estimated a 50 percent overdetection rate with annual screening for men ages 55 to 67 [17]. Given that the screening group in the ERSPC had a 71 percent higher cumulative incidence of prostate cancer than the control group (8.2 versus 4.8 percent) [13], the potential absolute risk for overdiagnosis is substantial.
- A study examined the number of men diagnosed and treated for prostate cancer in the United States (US) each year after 1986, the year before PSA screening was introduced, until 2005 [151]. The study estimated that approximately 1.3 million additional men were diagnosed with prostate cancer as a result of screening, of whom approximately 1 million were treated. Assuming that the entire decline in prostate cancer mortality in the US from 1986 through 2005 was due to screening, an extremely optimistic assumption for PSA screening, approximately 23 men had to be diagnosed and 18 men treated for prostate cancer to prevent one death. The authors concluded that most of the additional cases of prostate cancer found since 1986 represent overdiagnosis.
The risk of overdiagnosis of prostate cancer appears to increase with increasing age [152].
Risks of therapy — Even in the absence of treatment, many men found to have prostate cancer as a result of screening will have a lengthy period of time without clinical problems. However, undergoing radical prostatectomy and radiation therapies can lead to immediate complications:
- The operative mortality rate is about 0.5 percent [153], though the rate approaches 1 percent in men over 75 years [154].
- Less serious, but more common complications include urinary incontinence, sexual dysfunction, and bowel problems. Radical prostatectomy can substantially decrease sexual function in 20 to 70 percent of men and lead to urinary problems in 15 to 50 percent [14,155,156].
External beam radiation therapy has been reported to cause erectile dysfunction in 20 to 45 percent of men with previously normal erectile function, urinary incontinence in 2 to 16 percent of previously continent men, and bowel dysfunction in 6 to 25 percent of men with previously normal bowel function [14,155,157].
Given the ERSPC study estimate that 48 men need to be diagnosed with prostate cancer (of whom at least 60 percent received surgery or radiation) to prevent one prostate cancer death during nine years of follow-up, the quality of life issues related to treatment selection are very important decision-making factors.
APPROACH TO SCREENING — Although screening for prostate cancer with PSA can reduce mortality from prostate cancer, the absolute risk reduction is very small. Given limitations in the design and reporting of the randomized trials, there remain important concerns about whether the benefits of screening outweigh the potential harms to quality of life, including the substantial risks for overdiagnosis and treatment complications. Men who are willing to accept a substantial risk of morbidity associated with treatment in return for a small reduction in mortality might reasonably choose to be screened. Men who are at increased risk of prostate cancer because of race or family history may be more likely to benefit from screening.
Informed decision making — Given the important tradeoffs between potential benefits and harms involved with either screening or not screening for prostate cancer, and the lack of definitive data on screening outcomes, it is particularly important that patients make informed decisions about undergoing testing [158-161].
The United States Preventive Services Task Force Guidelines [162], American College of Physicians [163], American Urologic Association [164], American Cancer Society [44], and the Canadian Task Force on the Periodic Health Examination [165] all stress the importance of informed decision making.
The American College of Physicians and the American Cancer Society have provided useful summaries of discussion points to consider when counseling patients about prostate cancer screening [44,163]:
- Prostate cancer is an important health problem; it is one of the most frequently diagnosed cancers in the United States and a leading cause of cancer death in men.
- Men should be involved in making the decision whether or not to be screened.
- Prostate cancer screening may reduce the chance of dying from prostate cancer. However, the evidence is mixed and the absolute benefit is small.
- Prostate cancer screening is associated with a substantial risk of being diagnosed with prostate cancer. Many cancers detected by screening are considered "overdiagnosed", meaning that they never would have caused problems during a man's lifetime.
- In order to determine whether a cancer is causing an abnormal test, men need to undergo a prostate biopsy. However, the PSA test and digital rectal exam (DRE) can both have false positive and false negative results and prostate biopsies may also miss finding cancers.
- The PSA blood test with or without the DRE can detect cancer at an earlier stage than when cancers are found because they are causing problems.
- Aggressive therapy is necessary to realize any benefit from finding an early-stage prostate cancer.
- Surgery and radiation therapies are the treatments most commonly offered in an attempt to cure prostate cancer; however, they can lead to problems with urinary, bowel, and sexual function.
- No current tests can accurately determine which men with a cancer found by screening are most likely to benefit from aggressive treatment (ie, those whose cancers are destined to cause health problems). Most men with prostate cancer will die from other causes, many will never experience health problems from their cancer.
- A strategy of active surveillance may be appropriate for men who are at low risk for complications from prostate cancer. This means not immediately treating a cancer but following PSA tests, DRE, and repeating biopsies to determine whether aggressive treatment is indicated because the cancer is progressing.
Clinicians find it challenging to provide comprehensive, consistent, and balanced information about prostate cancer screening decisions during clinic visits [12,166]. Consequently, efforts have focused on using decision aids to help patients understand screening issues and make informed decisions for screening [167,168]. The American Cancer Society provided a list of Decision Aids for Prostate Cancer Screening (table 2) [44].
Investigators have evaluated a number of interventions to facilitate such informed prostate cancer screening decisions including videotapes [169-171], patient group discussions [169], brief scripts read to patients during clinic visits [172], verbal and written material provided before a periodic health examination [173], and informational pamphlets distributed at study visits [174] or through the mail [175].
The various strategies of providing information were shown to be consistently effective in increasing patient knowledge about prostate cancer and screening [169-171,174,175]. One study also found that providing men with screening information increased their involvement in making screening decisions and lowered their levels of decisional conflict [173].
Most studies have also demonstrated that men receiving screening information report less interest in undergoing PSA testing [169-171,175] or receiving aggressive prostate cancer treatment [169,170,172,175]. As an example, one study randomly assigned 176 men to usual care, a face-to-face discussion of PSA testing, a videotape developed by The Foundation for Informed Medical Decision Making [170], or a combination of videotape and discussion [169]. Among men assigned to usual care, 98 percent selected PSA testing, compared with 82 percent with the discussion, 60 percent with the videotape, and 50 percent with the combined intervention.
Another study showed that an educational pamphlet was comparable to the above videotape in enhancing patient knowledge about prostate cancer, increasing participation in decision making for screening, and altering screening preferences [176].
The content of a screening discussion or the provision of a decision aid should be documented in the medical record, particularly when the patient decides against screening.
Age to begin screening — Screening should be discussed with men beginning at age 50, though not with men who have a comorbidity that limits their life expectancy to less than 10 years [39,44].
We suggest that black men, men with a family history of prostate cancer, particularly in relatives younger than age 65, and men who are known or likely to have the BRCA1 or BRCA2 mutations should first discuss screening at age 40 to 45 [44,177,178]. (See "Risk factors for prostate cancer", section on 'Genetic factors'.)
Others, including other authors for UpToDate, suggest not initiating screening discussions earlier in higher risk men, given that age is a primary determinant of risk and earlier discussions may increase the risk of harms related to screening. (See "Overview of preventive medicine in adults", section on 'Prostate cancer'.)
Frequency and method of screening — When a decision is made to screen for prostate cancer, the recommended strategy has been to perform a digital examination and measure a PSA level [39,44]. However, the randomized ERSPC found that PSA screening alone, measured at an average interval of four years (range two to four years), resulted in a significant, though small, reduction in prostate cancer mortality [13]. The PLCO study, which screened with annual PSA and DRE, found no reduction in mortality [15]. The optimal interval and combination of tests remains uncertain, however based on current data we suggest screening every two to four years with PSA alone.
An analysis from the ERSPC compared outcomes from two centers with different screening intervals, Gothenburg (2 years; n = 4202) and Rotterdam (4 years; n = 13,301) [179]. The 10-year incidence of prostate cancer was significantly higher in the center with the shorter screening interval (13.1 versus 8.4 percent). Aggressive interval cancers were uncommon, and cumulative rates of such cancers were similar in the two centers (0.11 versus 0.12 percent, respectively). Follow-up was not long enough to compare mortality rates. There were potentially important differences between the patients and screening methods at these two centers that limit the strength of this nonrandomized comparison of screening intervals.
One study that applied modeling to identify an optimal PSA testing strategy concluded that the most efficient strategy would be to screen men at age 40 and 45 years and then biannually from ages 50 to 75, while still using the 4.0 ng/mL cutoff as a criterion for biopsy referral [180].
Studies have also raised the possibility of less frequent retesting in men with lower initial PSA levels (eg, ≤1.0, 1.5. or 2.0 ng/mL), while still testing annually in those with higher PSA levels (but still below a cutoff for biopsy) [181-183]:
- The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial found that only 1.5 percent (95% CI 1.2-1.7) of men with an initial PSA less than 1 ng/mL converted to a PSA greater than 4.0 ng/mL after five years [181]. The report estimated that only 0.12 percent of men with an initial PSA less than 1 ng/mL would be diagnosed with prostate cancer during a five-year interval. The initial PSA level was not correlated with conversion to an abnormal digital rectal examination (DRE); conversion within three years of baseline screening was nearly 10 percent, even for men with an initial PSA level below 1 ng/mL.
- Similar findings for PSA screening were noted in the European Randomized Study of Screening for Prostate Cancer (ERSPC) in which the proportion of men with a baseline PSA below 1.0 ng/mL who converted to a level above 3.0 ng/mL was 0.9 percent after four years [182]. The estimated cancer detection rate was 0.15 percent during a four-year interval.
In the PLCO trial, a four-year screening interval in men with a PSA below 1.0 ng/mL was estimated to result in a delay in cancer diagnosis of 15.6 months [181]. A separate report came to a similar estimate [184]. The clinical consequences of delayed diagnosis on prostate cancer mortality and morbidity are unknown, although the majority of cancers detected after a four-year screening interval in the ERSPC were early-stage [182].
Referrals for biopsy — Men with abnormal prostate exams (nodules, induration, or asymmetry) should be referred to a urologist for a transrectal ultrasound-guided prostate biopsy.
Men with abnormal PSA values can also be referred for biopsy, though some experts recommend first repeating the PSA several weeks later, particularly for borderline elevations below 7.0 ng/mL [57,69]. PSA measurements have considerable short-term variability [68,185]. A retrospective analysis of stored serum from 972 men found substantial year-to-year fluctuations with 44 percent of men with a PSA above 4.0 ng/mL having normal PSA findings at subsequent annual visits [186].
In addition to biological variability, PSA may be transiently elevated due to ejaculation, perineal trauma, or prostatitis. Before repeating a borderline elevated PSA test, patients should be asked to refrain from sexual activity and bike riding for at least 48 hours and, if there is evidence of prostatitis, complete a course of antibiotics. (See "Acute and chronic bacterial prostatitis".)
While a PSA level of 4.0 ng/mL had been considered abnormal, the ERSPC used lower PSA ranges (2.5 to 3.0 ng/mL) in conjunction with ancillary tests (DRE, transrectal ultrasonography) to guide biopsy referrals [13]. The PLCO, which used a PSA level of 4.0 ng/mL, found no survival benefit for screening, which lead investigators to question whether a lower PSA threshold should be used [15]. We suggest that a PSA level of 3.0 ng/mL be considered abnormal in determining who should be referred for biopsy.
Biopsy referrals may also be based upon PSA velocity, PSA density, measurements of free or complexed PSA, and age- and race-specific PSA levels, although the clinical utility of these modifications is uncertain. However, retrospective analyses of data from the ERSPC suggest that the predictive value of PSA for detecting cancer is not improved by incorporating PSA velocity data [71-73].
Attempts have been made to create risk models for prostate cancer based on multiple variables (eg, PSA, family history, DRE result, PSA velocity, etc.) [74]. Until such models have undergone additional study, we do not recommend using them to decide who should undergo biopsy.
Repeat biopsies — If a biopsy is positive, the cancer will be staged, and the patient will be presented with treatment options. AUA guidelines recommend that patients should resume routine screening if the biopsy is negative [39]. However, given the potential for false-negative results, some investigators have recommended repeating the biopsies.
A study that repeated 100 negative sextant biopsies found cancer in 20 percent [35]. Among five men with high-grade PIN at initial biopsy, all had carcinoma detected on repeat biopsy, as did 5 of 17 (29.4 percent) of men with atypia; only 10 of 69 (14.5 percent) men without PIN or atypia had cancer detected. PSA levels above 20 ng/mL also predict positive repeat prostate biopsies [187].
In a study of serial biopsies in 1051 Austrian and Belgian participants in the European Prostate Cancer Detection study with PSA levels between 4.0 to 10.0 ng/mL, cancer was detected in 83 of 820 (10 percent) men with BPH who underwent repeat biopsy six weeks after a negative biopsy [188]. A percent free PSA less than 30 percent and a PSA density greater than 0.26 ng/mL/cc were the most accurate predictors of cancer detection with areas under the ROC curves of 74.5 and 61.8 percent, respectively. Cancer was detected in 5 percent of men undergoing a third biopsy and 4 percent of men undergoing a fourth biopsy. However, tumors detected with these biopsies were significantly smaller and better differentiated than tumors found with the first two biopsies. The authors concluded that repeating one biopsy was justified [189].
In contrast, 272 men in the screening arm of the ERSPC, Rotterdam had a PSA ≥4.0 ng/mL and a negative biopsy and underwent repeat screening four years later [190]. In 217 of the men with a repeat PSA ≥3.0 ng/mL a biopsy was performed; prostate cancer was found in 18 (positive predictive value 8.3 percent). The majority (88.5 percent) of cancers detected during the second round of screening were organ confined, and the authors concluded that there was no need for immediate repeat biopsies in men with a PSA ≥4.0 ng/mL and a negative initial biopsy.
Another analysis of the ERSPC, Rotterdam data evaluated factors associated with having cancer detected during the second round of screening among men with a previous negative biopsy [191]. Having a previous negative biopsy was the only factor significantly associated with biopsy outcome in the second round of screening. Among 459 men with a previous negative biopsy who underwent a second biopsy because their PSA level was still elevated on the second round of screening, only 48 cancers were detected (positive predictive value 10.5 percent). In comparison, 149 cancers were diagnosed in men with elevated PSA levels who had not been previously biopsied (positive predictive value 25.6 percent). After adjusting for the previous negative biopsy in multivariate models, investigators did not find that either total PSA level (all were above 3.0 ng/mL) or PSA velocity significantly predicted finding cancer on the second biopsy.
We suggest that men with negative extended biopsies (biopsies performed using an extended protocol as opposed to just sextant biopsies) be managed similarly to men who have not previously undergone screening. That is, when screening is next routinely considered, men should again make an informed decision about testing; if the decision is made to screen, the same criteria used for the initial biopsy referral should again be applied. (See "Prostate biopsy".)
Stopping screening — Screening for prostate cancer is unlikely to benefit men with less than a 10-year life expectancy given the generally indolent course of the disease. While most agree with stopping screening of men who develop substantial comorbidities, applying an upper age limit to screening has less of a consensus.
- Actuarial tables suggest that among men in average health, only those ages 75 and younger have a 10-year life expectancy, and guidelines recommend against screening older men.
- An analysis of data from the Baltimore Longitudinal Aging Study found that discontinuing PSA testing at age 65 for men with PSA levels 0.5 ng/mL or less would still identify all cancers that would have been detected by age 75 [192]. If screening were discontinued for men with PSA levels of 1.0 ng/mL or less at age 65, then 94 percent of the cancers would still be detected.
- A case-control study from a population-based cohort in Sweden estimated that a PSA level ≤1 ng/mL at age 60 was associated with an extremely low risk of prostate cancer metastasis (0.5 percent) or death from prostate cancer (0.2 percent) by age 85 [193].
- A population-based cohort study using SEER-Medicare linked data evaluated outcomes of 89,877 older men (median age 78) diagnosed with clinically localized prostate cancer between 1992 and 2002 who were managed without attempted curative therapy. The 10-year prostate cancer specific mortality ranged from 8.3 percent (95% CI 42-12.8 percent) for men with well-differentiated cancers to 25.6 percent (CI 23.7-28.3 percent) for men with poorly-differentiated cancers. Approximately 60 percent of all subjects died from competing causes [194].
- Another SEER-Medicare analysis highlighted the importance of considering comorbidity. Among men with localized prostate cancer aged 75 and older, the 10-year prostate cancer mortality without attempted curative therapy was only 5.0 percent (CI 2.5-8.7 percent) for those with moderately-differentiated cancers and two or more comorbidities. The 10-year prostate cancer mortality was 18.8 percent (CI 9.3-36.8 percent) for men with poorly-differentiated cancers and two or more comorbidities [195].
- A decision analysis using Medicare data found that aggressively treating men age 70 and older could actually decrease the quality adjusted life expectancy [196].
- In contrast, another decision model, using results from the Scandinavian randomized trial of radical prostatectomy versus watchful waiting and case series utilizing three-dimensional conformal external beam radiation, concluded that many healthy men in their 70s or 80s with at least moderate-grade disease would benefit from aggressive therapy. However, subsequent results from the Scandinavian trial suggest that mortality benefits from radical prostatectomy may be limited to men younger than age 65.
Currently, clinical trial data are insufficient to resolve this issue.
RECOMMENDATIONS OF OTHERS — The American Cancer Society and American Urological Association have reissued guidelines following the publication of trial data from the ERSPC and PLCO studies.
- The American Cancer Society (ACS) emphasizes the need for involving men in the decision whether to screen for prostate cancer. Men need to have sufficient information regarding the risks and benefits of screening and treatment to make an informed and shared decision; providing them with a decision aid may facilitate the decision-making process [44]. For men who decide to be screened, the ACS recommends PSA testing with or without DRE for average-risk men beginning at 50 years of age. Screening should not be offered to men with a life expectancy less than 10 years. Men whose initial PSA level is greater than or equal to 2.5 ng/mL should undergo annual testing; men with a lower initial level can be tested every two years. The guidelines also recommend beginning screening discussions at age 40 to 45 in patients at high-risk of developing prostate cancer (eg, black men and men with a first-degree relative with prostate cancer diagnosed before age 65). The guideline also recommends keeping the biopsy referral threshold at 4.0 ng/mL. However, for men with PSA levels from 2.5 to 4.0 ng/mL, the guideline encourages individualized decision making and assessment (http://deb.uthscsa.edu/URORiskCalc/Pages/uroriskcalc.jsp) which can include age, race, family history, digital rectal examination findings, previous biopsy results, and use of five alpha-reductase inhibitors.
- The American Urological Association continues to recommend informing men about the risks and benefits of prostate cancer screening and treatment [164]. Screening should be performed annually with both PSA and DRE; however, the guideline now recommends that average-risk men consider obtaining a baseline PSA at age 40 if their life expectancy is greater than 10 years. The decision regarding the age to stop screening should be individualized based on presence of comorbidities and family history of longevity. Furthermore, the AUA no longer recommends a single threshold value of PSA for biopsy referral. Instead, biopsy detections should consider multiple factors, including free and total PSA, PSA velocity, DRE findings, age, race/ethnicity, family history, previous biopsy results, and comorbidities.
- The United States Preventive Services Task Force (USPSTF) concluded in 2008 that there was insufficient evidence to assess the balance of benefits and harms of prostate cancer screening in men younger than age 75 [197]. The USPSTF recommended against screening for prostate cancer in men ages 75 or older because the harms of screening outweigh the benefits. In October 2011, the USPSTF published a draft revision to their prostate cancer screening recommendation, which recommended against screening for prostate cancer with PSA testing, regardless of age, race, or family history [198]. The draft did advise that men requesting screening be supported in making an informed decision. The USPSTF clinical practice guideline for screening for prostate cancer, as well as other USPSTF guidelines, can be accessed through the website for the Agency for Healthcare Research and Quality at www.ahrq.gov/clinic/uspstfix.htm.
- The Canadian Task Force on Preventive Health Care recommends against screening for prostate cancer with PSA or TRUS and states that there is insufficient evidence to recommend for or against screening with DRE [199].
- The United Kingdom National Screening Committee does not recommend screening for prostate cancer [200].
- The Australian Cancer Council states that the evidence does not support population-based screening and recommends a patient-centered approach that individualizes the decision [201].
- The American College of Physicians (ACP) recommendation states that "Rather than screening all men for prostate cancer as a matter of routine, physicians should describe the potential benefits and known harms of screening, diagnosis, and treatment; listen to the patient's concerns; and then individualize the decision to screen" [163]. The ACP also suggests that men between the ages of 50 to 69 years are most likely to benefit from screening. Black men and men with a positive family history of prostate cancer should be informed of their higher lifetime risk, although the available evidence does not suggest that they need to be treated differently from men at average risk.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)
SUMMARY AND RECOMMENDATIONS — Although screening for prostate cancer with PSA can reduce mortality from prostate cancer, the absolute risk reduction is very small. Given limitations in the design and reporting of the randomized trials, there remain important concerns about whether the benefits of screening outweigh the potential harms to quality of life, including the substantial risks for overdiagnosis and treatment complications. (See 'Approach to screening' above.)
- Because individual patient preferences for specific health outcomes are a deciding factor in determining whether to screen for prostate cancer, men who are potential candidates for screening should be engaged in discussions or decision-making processes that inform them and evoke these preferences:
- Discussions should present men with information on the risks and benefits of screening, such as those in the summary points suggested by the American Cancer Society that are discussed above. (See 'Informed decision making' above.) Using existing written or video decision aids may help ensure that patients receive consistent, complete, and objective information and may optimize the time spent discussing screening during a clinic visit.
- Health care providers should periodically discuss prostate cancer screening with men who are expected to live at least 10 years and are old enough to be at significant risk for prostate cancer. We suggest that discussions begin at age 50 in average risk white men and at age 40 to 45 in black men, men with a positive family history, and men who are known or likely to have the BRCA1 mutation (Grade 2B). Men who are at increased risk of prostate cancer because of race or family history may be more likely to benefit from screening. (See 'Age to begin screening' above.)
- When a decision is made to screen, we suggest that screening be performed with prostate specific antigen (PSA) tests at intervals ranging from every two to four years (Grade 2B). We suggest not performing digital rectal examination as part of screening (Grade 2C). (See 'Frequency and method of screening' above.)
- When a decision is made to screen, we suggest that screening be performed until comorbidities or age (75 years) limit life expectancy to less than 10 years or the patient decides against further screening (Grade 2B). Stopping screening at age 65 may be appropriate if the PSA level is less than 1.0 ng/mL. (See 'Stopping screening' above.)
- Men with an abnormal DRE or PSA level above 7 ng/mL should be referred for transrectal ultrasound-guided prostate biopsy without further testing. (See 'Referrals for biopsy' above.)
- We suggest that men with a PSA level between 3 ng/mL and 7 ng/mL undergo repeat testing several weeks later (Grade 2C). Prior to repeat PSA testing, men should abstain from ejaculation and bike riding for at least 48 hours. Men with prostatitis should be treated with antibiotics before retesting. Men with a repeat PSA level above 3 ng/mL should be referred for transrectal ultrasound-guided prostate biopsy. (See 'Referrals for biopsy' above.)
- We suggest not considering PSA velocity in deciding which men should be referred for biopsy (Grade 2C). (See 'PSA velocity' above.)
- We suggest that men with negative extended biopsies (biopsies performed using an extended protocol as opposed to just sextant biopsies) be managed similarly to men who have not previously undergone screening (Grade 2C). That is, when screening is next routinely considered, men should again make an informed decision about testing; if the decision is made to screen, the same criteria used for the initial biopsy referral should again be applied. (See 'Repeat biopsies' above.)
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