Screening for lung cancer. Too many uncertainties, even for smokers

Lung cancer is the leading cause of death from cancer. It is often diagnosed at an advanced stage when curative treatment is no longer possible. Does organised screening reduce overall mortality andlor lung cancer mortality, especially in current smokers or former heavy smokers? To answer this question, we reviewed the literature using the standard Prescrire methodology. According to a meta-analysis of seven trials, and a large randomised trial (the PLCO study) involving 155 000 persons, screening the general population by means of plain chest radiography does not reduce mortality from lung cancer but carries a high risk of false-positive findings. In 2013, results from four randomised controlled trials evaluating low-dose computed tomography (CT) for lung cancer screening are available. The NLST trial, in 53000 individuals at high risk of cancer, showed a reduction in mortality from lung cancer after 6.5 years of follow-up (1.3% with annual low-dose CT screening versus 1.7% with plain chest radiography). Interim analyses of the Dante, Dlsct and Mild studies, in respectively 2470, 4100 and 4099 persons at high risk of cancer, showed no reduction in lung cancer mortality after low-dose CT screening. Low-dose CT screening carries a risk of adverse effects, including false-positive results in about 20% of patients, and about 90% of the nodules discovered are false-positives. This screening method also carries a risk of invasive diagnostic procedures, and repeated irradiation. In 2013, the harm-benefit balance of lung cancer screening with low-dose CT has not been adequately evaluated to justify its use in individuals with no signs or symptoms suggestive of lung cancer.