INTRODUCTION — Approximately 230,480 American women are diagnosed with breast cancer annually, and 39,520 women die from this disease [1]. Global cancer statistics show that breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death among females, accounting for 23 percent of total cancer cases and 14 percent of cancer deaths [2]. Breast cancer is now also the leading cause of cancer death among females in economically developing countries.
Despite increasing incidence rates, annual mortality rates from breast cancer have decreased over the last decade (1.8 percent per year from 1998 to 2007) [3]. The decline has been more pronounced in Caucasian than in African-American women. (See "Epidemiology and risk factors for breast cancer".)
A significant portion of the decline in mortality is attributable to the impact of screening mammography, which permits diagnosis at an earlier stage of disease [4]. Preinvasive breast cancer (ductal carcinoma in situ, DCIS) now accounts for 25 to 30 percent of all newly diagnosed, mammographically detected breast cancers. (See "Screening for breast cancer" and "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis", section on 'Mammographic screening'.)
The majority of breast cancers are diagnosed as a result of an abnormal mammogram, but not all mammographic findings represent cancer. Women who have an abnormal screening mammogram often need further diagnostic evaluation with magnification views, spot compression views and/or targeted ultrasonography to determine the need for tissue sampling or biopsy. Additionally, not all cancers are detectable on mammography. A clinically suspicious mass should also be biopsied, regardless of imaging findings, as about 15 percent of such lesions can be mammographically occult [5]. The goal of the initial biopsy is to obtain sufficient diagnostic material using the least invasive approach and to avoid surgical excision of benign lesions. (See "Breast biopsy".)
This review will discuss the diagnostic evaluation and management of a woman with suspected breast cancer due to either abnormal imaging or physical findings. Initial staging work-up of patients with newly diagnosed breast cancer, the general approach to evaluation of breast lumps in women, and breast biopsy techniques are discussed separately. (See "Initial work-up and staging after a new diagnosis of breast cancer" and "Breast masses and other common breast problems" and "Breast biopsy".)
IMPORTANCE OF MULTIDISCIPLINARY CARE — A suspicion of breast cancer requires that care be coordinated among clinicians in several specialties. An integrated approach with breast imagers and breast surgeons can minimize unnecessary biopsies and expedite diagnosis for the woman who receives a diagnosis of breast cancer. Similarly, once the diagnosis of cancer is made, multidisciplinary coordination among breast and reconstructive surgeons, radiation and medical oncologists, radiologists and pathologists facilitates treatment planning and streamlines patient care [6].
MAMMOGRAMS — The majority of breast cancers are associated with abnormal mammographic findings [7,8]. As an example, in the Breast Cancer Detection Demonstration Project (BCDDP), fewer than 10 percent of cancers were detected solely by physical examination and over 90 percent were identified mammographically [7].
If an abnormality is found at mammographic screening, supplemental mammographic views and possibly ultrasound should be used for further characterization. A variety of mammographic techniques, including spot compression and magnification views (picture 1) and varied angled views, may characterize a lesion more precisely prior to making a final recommendation for management. (See "Breast imaging: Mammography and ultrasonography", section on 'Diagnostic mammogram'.)
Some of the most aggressive cancers appear between normal screening mammograms and are therefore termed interval cancers [9]. Younger women may present with large tumors prior to the age at which screening is usually recommended. Accordingly, when women present with a suspicious new mass, diagnostic mammograms should be part of the initial workup, despite young age or having had a negative routine screening mammogram.
Diagnostic mammography is associated with higher sensitivity but lower specificity as compared to screening mammography. In one prospective study of women with signs or symptoms of breast cancer, 15 percent (6279 of 41,427) of diagnostic mammograms were abnormal [5]. The sensitivity and specificity of diagnostic mammograms declined with breast density, younger age, and mammographic examination.
Screening mammography is discussed in detail elsewhere. (See "Screening for breast cancer", section on 'Mammography'.)
BI-RADS diagnostic categories — The radiologist summarizes the mammographic findings using the American College of Radiology (ACR) BI-RADS (Breast Imaging Reporting and Data System) final diagnostic assessment categories, which indicate the relative likelihood of a normal, benign, or malignant diagnosis [10].
The BI-RADS final assessment categories standardize both the reporting of mammographic findings and the recommendations for further management (ie, routine screening, short interval follow-up, or biopsy). Assessments are either incomplete (category 0) or final assessment categories (categories 1 through 6) as described on the table (table 1) [10].
If a mammogram is assigned category 0, additional evaluation is required for further characterization which may include additional mammographic views and or ultrasound, and rarely, magnetic resonance imaging (MRI). A BI-RADS designation of 4c or 5 should alert the pathologist that a malignant diagnosis is strongly suspected and that further evaluation of the specimen (and possible rebiopsy) is needed if the biopsy is initially interpreted as benign. (See "Breast imaging: Mammography and ultrasonography", section on 'The BI-RADS categories'.)
Mammographic features of breast cancer — There are two general categories of mammographic findings suggestive of a breast cancer: soft tissue masses and clustered microcalcifications.
Soft tissue mass/architectural distortion — The most specific mammographic feature of malignancy is a spiculated soft tissue mass; nearly 90 percent of these lesions represent invasive cancer (picture 2).
Approximately one-third of noncalcified cancers appear as spiculated masses, 25 percent as irregularly outlined masses, 25 percent as less specific round, oval or lobulated masses, less than 10 percent as well-defined round, oval, or lobulated masses, and 5 percent as areas of architectural distortion of dense tissue without an obvious mass [11].
The positive predictive value for malignancy of well-defined solid masses with benign imaging features is between 0 and 7 percent, and biopsy or short-term (three to six months) follow-up is considered appropriate management [12].
Clustered microcalcifications — Clustered microcalcifications are calcium particles of various size and shape measuring between 0.1 to 1 mm in diameter and numbering more than four to five per cubic centimeter. Microcalcifications are seen in approximately 60 percent of cancers detected mammographically (picture 3A-B). Histologically, these represent intraductal calcifications in areas of necrotic tumor (picture 4) or calcifications within mucin-secreting tumors such as the cribriform or micropapillary subtype of intraductal cancer. (See "Pathology of breast cancer: The invasive carcinomas".)
Linear branching microcalcifications (picture 3A-B), most commonly associated with the comedo histologic subtype, have a higher predictive value for malignancy than do granular (ie, nonlinear irregular calcifications of varying size and shape) microcalcifications, particularly for high grade DCIS. However, breast cancers, including DCIS, more often present with the granular type of calcifications [8]. Calcifications that are not suspicious for malignancy and considered benign include vascular and skin calcifications, rim-like calcifications, large coarse calcifications (picture 5), and smooth round or oval calcifications (picture 6).
Despite the association of microcalcifications with ductal carcinoma in situ (DCIS), mammographic appearance alone cannot differentiate between purely intraductal and invasive ductal breast cancers; there is no mammographic correlate of basement membrane invasion [13]. One-third of invasive carcinomas are associated with microcalcifications, with or without a soft tissue mass, and 10 percent of intraductal cancers present as a soft tissue mass without microcalcifications [8]. (See "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis", section on 'Mammography' and "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis".)
However, calcifications can also be stratified by risk for malignancy, and the BI-RADS 4a, 4b, and 4c categories are helpful in alerting the referring physicians, the pathologists, and surgeons to the underlying risk of malignancy [14]. Low risk calcifications are much more likely to be benign (table 1). (See 'BI-RADS diagnostic categories' above.)
Assessing the extent of disease — Mammographic assessment of the extent of DCIS and early invasive carcinoma begins during diagnostic mammography and continues through the biopsy, specimen management, and the postexcision mammogram [8]. Mammography of both breasts is particularly important in the patient with DCIS or invasive cancer who is considering breast conservation. Preoperative diagnostic mammography can help to define the extent of disease and may identify multifocal or multicentric cancer that could preclude breast conservation or signal a potential difficulty in achieving clear surgical margins. Multifocal disease is usually defined as involvement of several areas within a breast quadrant, probably representing disease along an entire duct. In contrast, multicentric disease involves multiple areas within different quadrants, probably representing involvement of multiple ducts.
Although the extent of mammographic nonlinear branching microcalcifications frequently underestimates the pathologic extent of the malignancy, the discrepancy is less than 2 cm in 80 to 85 percent of cases [15]. Several clusters of microcalcifications separated by normal appearing tissue should not be interpreted as multifocal or multicentric disease. Often, these represent areas of contiguous tumor that is only partially calcified within a ductal-lobule [15,16].
The combination of a mass and associated calcifications often indicates the presence of an extensive intraductal component (EIC). EIC is defined pathologically as DCIS found adjacent to an invasive carcinoma, accounting for more than 25 percent of the volume of disease. This finding can be a predictor for more widespread residual tumor (usually DCIS) following gross excision of the lesion [17]. (See "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis" and "Breast conserving therapy", section on 'Extensive intraductal component (EIC)'.)
Postoperative mammograms to look for residual calcifications after surgical resection should be considered when the microcalcifications are not clearly or completely documented on the specimen radiograph or when margins are close or positive [18-20]. If a re-excision is to be recommended on the basis of residual calcifications, care should be taken to ensure that the calcifications are associated with malignancy on histopathology and not benign tissue. Multifocal disease is not necessarily a contraindication to breast conservation, but is one of the factors that should be taken into consideration along with breast size relative to the extent of disease on imaging. (See "Breast conserving therapy" and "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis".)
A significant limitation of mammographic assessment of disease extent is the obscuring of the borders or extent of the primary tumor by dense overlying tissue. Dense breasts can limit the sensitivity of mammography both for detection of breast cancers and for delineating disease extent [21,22]. In this setting, contrast-enhanced breast magnetic resonance imaging (MRI) may complement mammographic staging. If the clinical extent of disease is larger than what can be appreciated by mammography, MRI may be considered. (See 'Breast MRI' below.)
Mammographic assessment of tumor size for the staging of multifocal disease presents a unique dilemma. Most staging classifications require that the largest tumor mass be utilized for T staging, even in cases where multifocal disease is suspected. However, others suggest that the total surface area, volume, or aggregate measurements are a better indicator of prognosis [23-25]. Accurate delineation of the extent of odd-shaped, irregular, or multifocal tumors is important for treatment planning. (See "Tumor node metastasis (TNM) staging classification for breast cancer".)
For invasive cancers that are contiguous to the chest wall and not completely included on mammographic projections, ancillary imaging techniques such as MRI may be necessary to assess posterior tumor extension and pectoralis fascia or muscle involvement if that will determine a change in surgical approach or the use of neoadjuvant therapy [26]. (See 'Assessment of ipsilateral disease with breast MRI' below.)
Significance of intramammary lymph nodes — Intramammary lymph nodes are detected in 1 to 28 percent of patients with breast cancer [27-31]. Benign nodes can often be distinguished from metastatic or infiltrated intramammary lymph nodes by their mammographic or sonographic appearance, but definitive assessment often requires histopathologic study [32]. The presence of intramammary lymph node metastases appears to confer a worse prognosis, both in women who otherwise have stage I breast cancer based upon tumor size and axillary nodal status and in those with stage II disease [27]. Isolated intramammary lymph node metastases are considered to represent stage II disease, even if the axillary nodes are uninvolved. (See "Tumor node metastasis (TNM) staging classification for breast cancer".)
ULTRASONOGRAPHY — Ultrasound can be used to differentiate between solid and cystic breast masses that are palpable or detected mammographically. In addition, ultrasound evaluation of the axilla can be used to detect lymph nodes that are suspicious for axillary metastases. Ultrasound provides guidance for interventional procedures of suspicious areas in the breast or axilla.
Breast ultrasound — Ultrasound (US) examination of the breast is an important diagnostic adjunct to mammography. In patients suspected of having a breast cancer, breast US is most useful in the following circumstances:
Breast US is often added to the initial diagnostic evaluation for women with a suspected breast cancer if there is a palpable mass or a density is seen on mammogram. The benefit of this approach was suggested in a series of 2020 patients (470 with a palpable mass) who underwent clinical exam, mammography, and breast US [34]. The systematic addition of breast US detected eight additional malignancies, and correctly downgraded 332 cases of suspected malignancy to no suspected malignancy (predominantly cysts or fibroadenoma). Thus, the main benefit of breast US was improved specificity when used in a targeted manner. The sensitivity, specificity, positive and negative predictive values for clinical examination plus mammography plus US were 96.9, 94.8, 39.2, and 99.9 percent, while the corresponding values for clinical examination plus mammography were 91.5, 87, 19.7, and 99.7 percent, respectively.
Axillary ultrasound — For women with clinically suspicious lymph nodes, preoperative axillary US with fine needle aspiration or core biopsy of suspicious areas provides a means to identify patients who have positive nodes. This information may be used to guide future additional surgery, radiation, or systemic therapy. (See "Initial work-up and staging after a new diagnosis of breast cancer", section on 'Lymph nodes' and "Sentinel lymph node biopsy for breast cancer: Indications and outcomes", section on 'The role of ultrasound in sentinel node evaluation'.)
BREAST MRI — Nearly all invasive breast carcinomas enhance on gadolinium contrast-enhanced MRI [40-54]. The sensitivity of breast MRI for breast carcinomas is between 88 and 100 percent [48,55-57]. However, a major disadvantage is the limited specificity of MRI due to enhancement of benign breast lesions [40,42,44-48,58-65]. In a meta-analysis of 44 studies evaluating diagnostic breast MRI in patients with breast lesions, pooled specificity was 72 percent [66]. Specificity can be improved, to some extent, by alterations in technique. The technique of breast MRI is discussed elsewhere. However, even using optimal technique, specificity is still insufficient to obviate the need for biopsy confirmation of an MRI abnormality. (See "MRI of the breast and emerging imaging technologies".)
Assessment of ipsilateral disease with breast MRI — MRI is more sensitive than mammography, ultrasound, or physical examination and identifies additional ipsilateral disease in about 16 percent of women with a known breast cancer [13,36,45,49,55,67-71]. Because MRI is so sensitive, it was assumed that preoperative MRI would estimate the extent of disease more accurately than conventional imaging, thereby improving surgical planning (eg, prompting a change to mastectomy when breast conserving therapy had been previously considered [72]) and enabling surgeons to better obtain clean margins in breast conserving surgery.
However, available data has shown that preoperative breast MRI has not improved outcomes:
In summary, the routine use of breast MRI to assess the extent of ipsilateral disease may increase the extent of surgery and delay treatment without improving oncologic outcomes. However, there are selected cases where breast MRI will add useful information for the assessment of ipsilateral disease:
Assessment of contralateral disease with breast MRI — MRI imaging of the contralateral breast identifies a suspicious, clinically occult finding in 9 to 12 percent of women with a unilateral breast cancer, but cannot distinguish between benign and malignant lesions. In general, a synchronous clinically and mammographically inapparent malignancy will be found in 3 to 5 percent of cases, approximately one-half of which are invasive cancer, and the remainder, intraductal cancer [35,50,85-94], and results in about a 12 percent chance of biopsy [35,50,85-92,95].
As an example, in a meta-analysis of 22 studies (3253 women) of women with newly diagnosed breast cancer, the pooled estimate for detecting a suspicious abnormality that was occult on conventional imaging was 9.3 percent [86]. The incremental cancer detection rate with MRI was only 4 percent because more than half of the suspicious abnormalities detected by MRI alone proved to be benign. The summary estimate of positive predictive value was 48 percent. Interestingly, 10 women underwent contralateral mastectomy based upon MRI findings without a preoperative biopsy. Of these, only three had malignancy and the remaining seven were benign. Of the 42 women who underwent prophylactic mastectomy despite a negative MRI, five (12 percent) unexpected malignancies were identified on final pathology.
The clinical significance, especially the survival benefit, of detecting these cancers has not been addressed. As is the case with MRI of the affected breast, the finding of a contralateral malignancy on breast MRI may lead to overtreatment. Many of these subclinical cancers are effectively treated with the systemic therapy used for the treatment of the initial cancer. As an example, in the Early Breast Cancer Trialists Collaborative Group (EBCTCG) overview analysis, the incidence of contralateral breast cancer was reduced by 50 percent in patients receiving five years of adjuvant tamoxifen, and by 20 percent in patients receiving adjuvant chemotherapy [96].
Finally, the detection of these contralateral cancers must be weighed against the added time and additional costs associated with MRI and MRI-guided biopsy. Of MRI-detected lesions recommended for biopsy, only about one in five prove to be malignant [97]. The available data do not show that detection rates or clinical utility differs in any subset of breast pattern (including dense breasts) or histologic type (DCIS, ductal or lobular carcinoma) [15,32,34,36,98]. (See "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis", section on 'Magnetic resonance imaging' and "Breast ductal carcinoma in situ: Epidemiology, diagnosis, and prognosis".)
For all of these reasons, the role of MRI to assess the contralateral breast is controversial and cannot be routinely recommended for the majority of women with a newly diagnosed breast cancer.
There are some clinical scenarios where breast MRI might be considered prior to therapy to assess contralateral disease.
High risk women — A contralateral breast MRI is reasonable for women with newly diagnosed breast cancer who are considered at very high risk for contralateral breast cancer based on the following criteria:
Issues related to breast reconstruction — Some surgeons prefer a preoperative MRI to assess the opposite breast in a woman undergoing significant reconstructive procedures such as a partial mastectomy with contralateral breast reduction or mastectomy with flap reconstruction:
Effect of tumor histology on MRI — Tumor histology does not appear to be a predictor for the utility of breast MRI. Although some studies have reported that MRI accurately determines disease extent for invasive lobular cancers, which are often associated with only subtle mammographic changes, this is not uniformly the case [15,32,34,36,98].
Although early studies reported difficulty in detecting ductal carcinomas in situ (DCIS) on MRI, subsequent studies suggest that MRI can accurately determine the extent of high grade DCIS, with sensitivities of 89 to 94 percent [36,50,100]. MRI detection of DCIS has been shown to improve with experience [101].
Effect of MRI on mastectomy rates — A number of studies have reported that MRI results in changes in surgical management and may be a factor in the increased use of mastectomy and bilateral mastectomy in women with newly diagnosed breast cancers [36,50-52,69,94,102,103]. As an example, in a population of 3606 women with newly diagnosed breast cancer, women who underwent MRI were twice as likely to have contralateral prophylactic mastectomy performed [87].
Effect of MRI on recurrence and survival rates — An unresolved question is whether the routine use of MRI to detect multifocal or multicentric disease results in fewer local recurrences and better long-term survival [37,38]. In a retrospective review of 756 patients treated for newly diagnosed breast cancer, 215 patients had breast MRI as part of their initial evaluation, and 541 did not [104]. The eight-year rates of any local failure or local-only first failure were 3 and 4 percent with and without MRI, respectively, and rates were similar in women who had invasive or intraductal cancers. Furthermore, there were also no differences in eight-year rates of overall or cause-specific survival.
Guidelines for the use of preoperative breast MRI — The use of breast MRI in the preoperative evaluation of a newly diagnosed breast cancer has increased significantly over the last ten years, largely due to the high sensitivity for detecting otherwise occult breast cancer in the affected and contralateral breasts. Advocates of MRI cite as potential benefits an improvement in the selection of patients for breast conserving surgery, a decrease in the number of surgical procedures needed to obtain clear margins, and the synchronous detection of contralateral cancers. However, there are no data from prospective randomized trials that demonstrate improved outcomes from the addition of breast MRI to the diagnostic evaluation of newly diagnosed breast cancer. Furthermore, because of limited specificity, the use of breast MRI increases unnecessary surgery, delays definitive treatment, and may lead to overtreatment.
Routine preoperative MRI is not indicated for the majority of patients with early stage breast cancer. In keeping with consensus-based guidelines from the National Comprehensive Cancer Network (NCCN) and the available data, we and others consider the role of breast MRI in the evaluation of women with newly diagnosed breast cancer as follows [20,93,97,105-107]:
DIAGNOSTIC ALGORITHMS — There is significant variability in the diagnostic evaluation of women with suspected breast cancer. Patterns of referral vary dramatically, as do rates of screening mammography recall. The work-up and evaluation may differ, depending upon which clinician is seen first. Diagnostic algorithms are helpful as general guidelines, but they must be adapted to include patient preferences.
Mammographic abnormalities — The figure (figure 1) describes an algorithmic approach to the evaluation of a mammographic abnormality, which integrates BI-RADS assessment categories (table 1).
Women with palpable masses — Algorithms for clinical and imaging evaluation of palpable masses are stratified by the age of the woman. Even in the setting of palpable masses, image guidance may improve diagnostic accuracy. A clinically suspicious mass should be biopsied regardless of imaging findings, as 10 to 15 percent of such lesions can be mammographically occult [9].
Younger women — The diagnostic approach to the evaluation of palpable masses in younger women differs among experts.
The approach that is advocated by the National Comprehensive Cancer Network (NCCN) is an initial breast US (figure 2 and figure 3) [20]. If the examination is indeterminate or suspicious, mammography is often performed, although its utility in young women with breast lumps is limited [108], and a biopsy is probably warranted even if the mammogram is negative. If the mass cannot be visualized by US, mammography may be considered, or alternatively, a tissue biopsy or period of observation may be appropriate depending upon the level of clinical suspicion. (See "Breast masses and other common breast problems" and "Breast biopsy".)
Alternatively, aspiration can be selected as an initial approach to a breast lump in a younger woman (figure 2) [20]. If no fluid is aspirated and cytologic review of cell blocks from the needle washings are nondiagnostic, then US is performed. If the capacity to perform or interpret FNA is limited at an institution, this approach is not optimal. (See "Breast biopsy".)
If the initial evaluation shows cancer, bilateral breast imaging should be performed promptly and prior to any definitive surgery to exclude unsuspected or more extensive disease.
Older women — If a palpable mass or lump is appreciated, bilateral diagnostic mammography should be performed prior to biopsy, even if the mass is clinically suspicious for cancer (figure 3 and figure 4) [20]. Fine needle aspiration or core needle biopsy may alter both mammographic or US appearance. The goal of imaging in this setting is not to establish a diagnosis of cancer, but rather to identify other suspicious areas or calcifications in either breast that might impact treatment. This evaluation should be performed prior to percutaneous biopsy, so that biopsy of additional suspicious lesions can be undertaken at one time. If the lesion is large and breast conservation is not an option, this is less important. (See "Breast biopsy".)
BIOPSY — In the patient with a suspicious mammographic abnormality or palpable breast mass, the obligatory diagnostic technique is biopsy. Surgical biopsy should not be utilized as a diagnostic tool unless percutaneous palpation-guided or image-guided biopsy is not feasible [109,110]. A preoperative histologic diagnosis of invasive carcinoma may allow the surgeon to plan a single operation to treat the cancer, including sentinel lymph node biopsy or full axillary dissection, depending upon the clinical circumstances. Excision of more extensive areas of DCIS may also be optimally planned if the diagnosis has been established by percutaneous core needle biopsy. (See "Breast biopsy".)
It is important to note that a needle biopsy may cause hematoma and inflammation at the site of the mass and enlargement of the axillary nodes, which can make clinical assessment and surgical planning more difficult. Physical exam changes from needle biopsy often resolve by the time of surgery. If the palpable lesion is small or subtle, it is helpful to arrange wire localization of the clip placed at the time of biopsy to facilitate breast conserving surgery. (See "Breast conserving therapy".)
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