If You Smoke (or Know Someone Who Smokes), Annual Screening for Lung Cancer Might be Life Saving

Lung cancers, the vast majority of which are caused by cigarette smoking, is the leading cause of cancer-related deaths in the United States.  Most lung cancers are detected when they cause symptoms.  By the time lung cancer is diagnosed, the disease has often already spread outside the lung.

Tobacco smoking causes about nine out of 10 cases of lung cancer; people who smoke have about 20x the risk of lung cancer compared to those who do not smoke. The damage caused by smoking is cumulative and the longer a person smokes, the higher the risk of disease.

Annual Screening for Lung Cancer Can Save Your Life

CT screening decreases the risk of dying from lung cancer.  Screening is done in people who do not have any symptoms of cancer.  A screening CT looks for initial signs of disease in healthy people, while a diagnostic CT is done after a person has a sign or symptom of the disease. The Fleischner Society, an international medical society for thoracic radiology, has established guidelines for diagnosing indeterminate lung nodules.

American Cancer Society guidelines recommend yearly lung cancer screening for people who meet certain criteria that puts them at higher risk for lung cancer.  These higher risk patients are aged 55 to 74 years, and are in fairly good health, currently smoke or have quit within the past 15 years and have a history of smoking the equivalent of a pack a day for 30 years.  Screening with low dose CT is not recommended for people who do not meet the criteria in the guidelines.

Talk with Your Doctor about Screening for Lung Cancer

For these higher-risk patients, the recommendations state that they need to: (a) be involved in shared decision making about the benefits, limitations and harms of screening; and (b) have access to a high volume, high quality lung cancer screening and treatment center.  If people decide to be screened, the recommendation specifies that the testing be done with a low dose CT and take place at a facility with experience in lung cancer screening.

Screening for lung cancer has the potential of finding the cancer earlier, when it might be easier to treat.  The National Lung Screening Trial (NLST) found that people who received low dose CT screening had a 20% lower chance of dying from lung cancer than those who received chest X-rays.

CT Scans are More Sensitive than Chest X-Rays in Screening

On average, over three screening rounds, 24.2% of the low dose helical CTs were positive and 6.9% of the chest X-rays were positive and led to a diagnostic evaluation.  Among people who had multiple annual screens (up to three screens), 39.1% had at least one positive screen in the CT and 16% had at least one positive screen in the chest X-ray.  A positive screening result was defined as one in which a nodule or other finding was observed that was potentially related to lung cancer.  The NLST was conducted by the American College of Radiology Imaging Network and the Lung Screening Study Group.

Low dose helical CT scans are better than chest X-ray in helping to reduce a person’s chances of dying from lung cancer.  Helical CT, a technology introduced in the 1990s, can detect tumors well under one centimeter or 0.4 inches in size, whereas chest X-rays detect tumors about one to two centimeters (0.4 to 0.8 inches) in size.  Chest X-ray screening has not been found to reduce deaths from lung cancer.

Low dose helical CT uses X-rays to scan the entire chest in about seven to 15 seconds and the CT scanner rotates around the patient, who is lying still on a table.  Recent studies indicate that 20% to 60% of screening CT scans of current or former smokers will show abnormalities.