Lung cancer is the leading cause of cancer-related death in the United States, with 87 percent of lung, bronchial, and tracheal cancer attributed to smoking. After reviewing the latest scientific evidence on the topic to update its 1996 recommendation on lung cancer screening, the U.S. Preventive Services Task Force concluded that the evidence remains insufficient to recommend screening asymptomatic individuals for lung cancer with either chest x-ray, low-dose computerized tomography (CT), sputum cytology (examination of a coughed sputum sample for cancerous cells), or a combination of these tests.
The Task Force found fair evidence that screening with any of these methods can detect lung cancer at an earlier stage than it would be detected in an unscreened population. However, it found poor evidence that any screening strategy decreased death rates from the disease. Because of the invasive nature of diagnostic testing and the possibility of a high number of false-positive tests (tests that indicate cancer where there is none) in certain populations, there is also the potential for significant harm from screening.
Researchers at the Oregon Evidence-based Practice Center, which is supported by the Agency for Healthcare Research and Quality (contract 290-97-0018), reviewed studies that evaluated mass screening programs for lung cancer with chest x-ray, sputum cytologic exam, and low-dose CT. None of the randomized trials of screening for lung cancer with chest x-ray alone or in combination with sputum cytologic examination showed benefit among those screened.
Six studies showed that when CT was used to screen for lung cancer, lung cancer was diagnosed at an earlier stage than in usual clinical care. However, these studies did not have control groups, making mortality evaluation difficult, and they had a high rate of false-positive findings. Two randomized trials of screening with chest x-ray or low-dose CT are currently underway and will better inform lung cancer screening decisions.
See "Lung cancer screening: Recommendation statement," by the U.S. Preventive Services Task Force," in the May 4, 2004, Annals of Internal Medicine 140(9), pp. 738-739.
Editor's Note: For a detailed account of the evidence on which this recommendation is based, see Humphrey, L.L., Teutsch, S., and Johnson, M. (2004, May). "Lung cancer screening with sputum cytologic examination, chest radiography, and computed tomography: An update for the U.S. Preventive Services Task Force." Annals of Internal Medicine 140(9), pp. 740-753.
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