Screening for lung cancer.

BACKGROUND: The effectiveness of screening for lung cancer with chest radiography, sputum cytology or spiral CT has not been established. OBJECTIVES: To determine whether screening for lung cancer using regular sputum examinations or chest radiography or CT chest reduces lung cancer mortality. SEARCH STRATEGY: Electronic databases, bibliographies, hand searching of a journal and discussion with experts were used to identify published and unpublished trials. SELECTION CRITERIA: Controlled trials of screening for lung cancer using sputum examinations, chest radiography or CT chest. DATA COLLECTION AND ANALYSIS: Intention to screen analysis was performed. Where there was significant statistical heterogeneity relative risks were reported using the random effect model, but for other outcomes the fixed effect model was used. MAIN RESULTS: Seven trials were included (6 randomised controlled studies and 1 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, CI: 1.00-1.23). A non statistically significant trend was observed 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, CI:0.74-1.03). Several of the included studies had potential methodological weaknesses. There were no controlled studies of spiral CT. REVIEWER'S 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.