Patient information: Lung cancer prevention and screening

LUNG CANCER SCREENING OVERVIEW

Lung cancer is the leading cause of cancer death in both men and women in the United States. The number of people who die from lung cancer each year has risen over the past 25 years. The number of people who die from lung cancer is greater than the number of people who die from breast cancer, prostate cancer, and colorectal cancer combined. Several factors increase the risk of lung cancer, particularly cigarette smoking.

This topic review discusses ways to prevent lung cancer and discusses the benefits and risks of screening for lung cancer. Other topics about lung cancer are available separately. (See "Patient information: Lung cancer risks, symptoms, and diagnosis" and "Patient information: Non-small cell lung cancer treatment; early stage (stage I and II) cancer" and "Patient information: Non-small cell lung cancer treatment; locally advanced (stage III) cancer" and "Patient information: Non-small cell lung cancer treatment; advanced unresectable, metastatic (stage IV), and recurrent cancer" and "Patient information: Small cell lung cancer treatment".)

PREVENTING LUNG CANCER

Cigarette smoking is responsible for almost 90 percent of cases of lung cancer. Exposure to certain substances, such as asbestos, has also been linked to the development of lung cancer. Exposure to second-hand smoke and other environmental factors may play a role.

The best way to avoid getting lung cancer is not to smoke. Some smokers believe that once they have smoked for a long while, it does little good to quit. However, studies have shown that smokers who quit decrease their risk of lung cancer when compared to those who continue to smoke. Smokers who quit for more than 15 years have an 80 to 90 percent reduction in their risk of lung cancer compared to people who continue to smoke. (See "Patient information: Smoking cessation".)

IS SCREENING WORTHWHILE?

Screening is a way to detect a disease in its earliest stages, before a person becomes ill or dies. To be recommended, it must be clear that screening is useful in identifying patients who have the disease in the early stages, and that this discovery can reduce the number of patients who become ill and/or die.

Some screening exams have proven to make a clear difference in outcomes. Examples are the Pap smear for detection of cervical cancer in women, and colonoscopy for detection of colon or rectal cancer in people over 50 years old. These exams are now part of routine health care in the United States.

LUNG CANCER SCREENING EXAMS

Research studies have been done to determine if screening for lung cancer makes sense. In these studies, smokers (who are at the highest risk) are divided into groups. Some groups have screening tests while others have no screening. The groups are then followed over many years. Data are gathered on how many patients in each group are diagnosed with lung cancer, how the cancer was treated, and how long the patients with lung cancer survived after treatment.

So far, the data from these studies have not shown that screening for lung cancer makes a difference in deaths from the disease. For this reason, expert medical advisory groups do not yet recommend lung cancer screening.

Still, the data from these studies are the subject of much debate. Part of the debate surrounds the fact that outcomes other than overall mortality, such as the stage of the disease at diagnosis and five-year survival rate, are improved in people who have screening. However, critics point out that data are difficult to interpret. The debate is continuing, and more studies are underway to better understand the role of screening studies for lung cancer.

Because of the lack of data on the efficacy of screening for lung cancer, most of the exams discussed below are not routinely recommended but are only offered to smokers as part of ongoing clinical trials. (See 'Clinical trials' below.) One exception may be an annual chest x-ray.

Chest x-ray — Many healthcare providers already recommend an annual chest x-ray for patients who smoke. Some experts, in analyzing data from lung cancer screening trials, have concluded that an annual chest x-ray is a worthwhile screening exam for patients with lung cancer.

Two major studies have been done to find out whether more frequent chest x-rays are helpful in lung cancer screening. So far, these studies have not shown a clear benefit in terms of deaths from lung cancer. In patients who had more frequent chest x-rays, more lung cancers were found at early stages, the cancers were more frequently removable by surgery, and the patients had longer five-year survival (from time of diagnosis) than patients with less frequent x-rays. However, overall death from lung cancer was not significantly different.

Computed tomography (CT scan) — Studies of computed tomography (CT scan) of the lung have shown that the test can help detect early stage lung cancer, but it is not yet clear whether this will affect the number of patients who die from their cancer.

Sputum tests — Some studies have looked at the efficacy of analyzing a patient's sputum for evidence of cancer cells in order to detect lung cancer. So far, no clear benefit to this approach has been found. Additional studies that use new technologies to examine the sputum are underway.

PET scan — Researchers are looking at a number of other tools in an effort to help identify patients with lung cancer. Positron Emission Tomography (or PET scanning, which uses a small amount of radioactivity to provide a detailed picture of an organ's function) has been used in combination with CT scanning.

Other studies — Direct visualization of the lungs with bronchoscopy and breath analysis for cancer markers are two tests that may be used in future studies.

CLINICAL TRIALS

Because the data on lung cancer screening are inconclusive, large-scale clinical trials of various screening modalities are underway. Smokers or former smokers may be asked to participate in these trials.

Although it makes sense to think that early detection of lung cancer is a good idea, it is important to understand that routine screening for lung cancer cannot be recommended until the research clearly shows that it makes a difference. It is likely that recommendations on lung cancer screening will evolve over the next decades as these data become available.

SUMMARY

• Patients who smoke are at increased risk of developing lung cancer. The best way to avoid lung cancer is not to smoke. Even long-term smokers can benefit from quitting.
• Researchers are looking for ways to help smokers and non-smokers who develop lung cancer to live longer. Early detection and screening is a major focus of this effort
• It is not clear if lung cancer screening can reduce the number of people who die from their disease. Clinical trials are underway that will help provide answers to these questions.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Lung cancer risks, symptoms, and diagnosis
Patient information: Non-small cell lung cancer treatment; early stage (stage I and II) cancer
Patient information: Non-small cell lung cancer treatment; locally advanced (stage III) cancer
Patient information: Non-small cell lung cancer treatment; advanced unresectable, metastatic (stage IV), and recurrent cancer
Patient information: Small cell lung cancer treatment
Patient information: Smoking cessation

Professional Level Information:
Cancer prevention
Chemoprevention of lung cancer
Cigarette smoking and other risk factors for lung cancer
Fluorescence bronchoscopy
Management of smoking cessation
Screening for lung cancer
Secondhand smoke exposure: Effects in adults
Women and lung cancer

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Cancer Institute

      (www.cancernet.nci.nih.gov/)

• The American Society of Clinical Oncology

      (www.cancer.net/portal/site/patient)

• The American Cancer Society

      (www.cancer.org)

• Lung Cancer Alliance

      (www.lungcanceralliance.org)

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