Reanalysis of epidemiological evidence on lung cancer and passive smoking

Abstract Objective: To assess the epidemiological evidence for an increase in the risk of lung cancer resulting from exposure to environmental tobacco smoke. Design: Reanalysis of 37 published epidemiological studies previously included in a meta-analysis allowing for the possibility of publication bias. Main outcome measure: Relative risk of lung cancer among female lifelong non-smokers, according to whether her partner was a current smoker or a lifelong non-smoker. Results: If it is assumed that all studies that have ever been carried out are included, or that those selected for review are truly representative of all such studies, then the estimated excess risk of lung cancer is 24%, as previously reported (95% confidence interval 13% to 36%, PConclusion: A modest degree of publication bias leads to a substantial reduction in the relative risk and to a weaker level of significance, suggesting that the published estimate of the increased risk of lung cancer associated with environmental tobacco smoke needs to be interpreted with caution. Key messages A systematic review of epidemiological studies on passive smoking estimated the increased risk of lung cancer as 24% There is clear evidence of publication bias in these studies Reanalysis of the data allowing for the possibility of publication bias substantially lowers the estimate of relative risk