Variations of lung cancer risk from asbestos exposure: impact on estimation of population attributable fraction.

The purpose of this study is to investigate the potential impact of differing lung cancer risks in study populations on estimating population attributable fraction (PAF) from asbestos exposure. Studies were identified via a MEDLINE search up to September 2009 and from the reference lists of publications about asbestos exposure and lung cancer risk. Relative risk estimates were extracted from 160 studies and meta-relative risks were calculated according to random-effect models. Hypothetical PAFs were calculated based on the meta results and on the difference exposure scenarios. The risks for lung cancer from asbestos exposure were variable according to the region as well as other study characteristics. The risk estimates proved higher in Asian countries (RR=3.53), in studies with 500 or fewer subjects (RR=2.26), and papers published in the 1990s or earlier (RR=1.91), than did those for European or North American countries, studies with more than 500 subjects, and papers published in the 2000s, respectively. The differences in PAFs between Asian and North American studies were 15.5%, 30.3%, and 36.2% when the exposure prevalence was 10%, 30%, and 50%, respectively. This study suggested that it is important to apply appropriate lung cancer estimates to each study population when calculating PAF from asbestos exposure.