A Cochrane review [Abstract] 1 included 9 studies (8 RCTs, one controlled trial) with a total of 453 965 subjects. In one large study (77 470 participants in the control group, 77 464 in the intervention group, both men and women between the ages of 55 and 74 years, including both smokers and non-smokers) comparing annual chest x-ray screening with usual care there was no reduction in lung cancer mortality (RR 0.99, 95% CI 0.91 to 1.07). .
In a meta-analysis of studies comparing different frequencies of chest x-ray screening, 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). However several of the trials included in this meta-analysis had potential methodological weaknesses. 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, 95% CI 0.74 to 1.03). In one large methodologically rigorous trial in high-risk smokers and ex-smokers (aged 55 to 74 years, with ≥ 30 pack-years of smoking or having quitted ≤ 15 years prior to entry if ex-smokers; 26 722 subjects assigned to annual screening with low-dose CT, 26 732 subjects to annual screening with chest radiography), the relative risk of death from lung cancer was significantly reduced in the low-dose CT group (RR 0.80, 95% CI 0.70 to 0.92).
Comment: The quality of evidence is downgraded by study quality (unclear or inadequate allocation concealment).
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