Usually symptoms of lung cancer do not appear until the disease is already in an advanced stage. Even when symptoms of lung cancer do appear, many people may mistake them for other problems, such as an infection or long-term effects from smoking. This may delay a diagnosis even further.

But some lung cancers are diagnosed early because they are found as a result of tests for other medical conditions. For example, a lung tumor may be noted by imaging tests (such as a chest x-ray or chest CT scan), bronchoscopy (viewing the inside of bronchi through a flexible lighted tube), or sputum cytology (microscopic examination of cells in coughed up phlegm) done for other reasons in patients with heart disease, pneumonia, or other lung conditions.

Screening for lung cancer

Screening is the use of tests or exams to detect a disease in people without symptoms of that disease. For example, the Pap test is used to screen for cervical cancer. Because lung cancer usually spreads beyond the lungs before causing any symptoms, an effective screening test for lung cancer could save many lives.

So far, no lung cancer screening test has been shown to prevent people from dying of this disease. Studies of chest x-rays and sputum cytology have concluded that these tests could not find many lung cancers early enough to improve a person's chance for a cure. For this reason, major medical organizations have not recommended these tests for screening the general public or even for people at increased risk, such as smokers.

Recently, a special type of CT scan known as spiral or helical CT has shown some promise in detecting early lung cancers in smokers and former smokers. But it is not known whether this test will lower the chances of dying from lung cancer. A major drawback of this test is that it also finds a lot of abnormalities that turn out not to be cancer but that still need to be tested to be sure. This may lead to unnecessary and invasive tests such as biopsies, or even surgery.

A large clinical trial called the National Lung Screening Trial (NLST) is now testing whether spiral CT scanning of people at high risk of lung cancer will save lives. The results of this study, which includes about 50,000 people, are not expected until at least 2010. Until this information is available, people who are interested in testing should understand the limits and benefits of screening with spiral CT.

No major professional organizations, including the American Cancer Society, currently recommend routine screening for lung cancer.

The American Cancer Society recommends that, as much as possible, people who were smokers, are current smokers, have been exposed to secondhand smoke, or have worked around materials that increase the risk for lung cancer, be aware of their lung cancer risk. These people should talk with their doctors about their likelihood of developing lung cancer and about the potential benefits and risks of lung cancer screening. After discussing what is and is not known about the value of testing for early lung cancer detection, if you and your doctor decide in favor of testing, then be sure to have it done at a center that has experience in lung scanning and that supports a multidisciplinary program for testing people at high risk.

The United States Preventive Services Task Force (USPSTF), a group of experts gathered together by the US government, has concluded that there's not enough evidence at this time to recommend for or against lung cancer screening in people without symptoms.

The American College of Chest Physicians (ACCP) does not recommend routine lung cancer screening at this time, advising that "individuals undergo screening only when it is administered as a component of a well-designed clinical trial."

People who are current smokers should realize that the best way to avoid dying from lung cancer is to stop smoking. For help quitting smoking, see our Guide to Quitting Smoking or call the American Cancer Society at 1-800-227-2345.

Last Medical Review: 10/20/2009
Last Revised: 10/20/2009