Screening for lung cancer

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Abstract
Background Population based screening for lung cancer has not been adopted in the majority of countries, however it is not clear whether sputum examinations, chest radiography or newer methods such as computed tomography (CT) are effective in reducing mortality from lung cancer. Objectives To determine whether screening for lung cancer, using regular sputum examinations, chest radiography or CT scanning of the chest, reduces lung cancer mortality. Search methods We searched electronic databases (the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 4), MEDLINE (1966 to 2007), PREMEDLINE and EMBASE (to 2007)) and bibliographies. We handsearched the journal Lung Cancer (to 2000) and contacted experts in the field to identify published and unpublished trials. Selection criteria Controlled trials of screening for lung cancer using sputum examinations, chest radiography or chest CT. Data collection and analysis We performed an intention‐to‐screen analysis. Where there was significant statistical heterogeneity, we reported relative risks (RR) using the random‐effects model. For other outcomes we used the fixed‐effect model. Main results We included seven trials (six randomised controlled studies and one non‐randomised controlled trial) with a total of 245,610 subjects. There were no studies with an unscreened control group. Frequent screening with chest x‐rays was associated with an 11% relative increase in mortality from lung cancer compared with less frequent screening (RR 1.11, 95% CI 1.00 to 1.23). We observed a non‐statistically significant trend to reduced mortality from lung cancer when screening with chest x‐ray and sputum cytology was compared with chest x‐ray alone (RR 0.88, 95% CI 0.74 to 1.03). Several of the included studies had potential methodological weaknesses. There were no controlled studies of spiral CT. Authors' conclusions The current evidence does not support screening for lung cancer with chest radiography or sputum cytology. Frequent chest x‐ray screening might be harmful. Further methodologically rigorous trials are required.