Estimating the asbestos-related lung cancer burden from mesothelioma mortality

BACKGROUND: Quantifying the asbestos-related lung cancer burden is difficult in the presence of this disease's multiple causes. We explore two methods to estimate this burden using mesothelioma deaths as a proxy for asbestos exposure. METHODS: From the follow-up of 55 asbestos cohorts, we estimated ratios of (i) absolute number of asbestos-related lung cancers to mesothelioma deaths; (ii) excess lung cancer relative risk (%) to mesothelioma mortality per 1000 non-asbestos-related deaths. RESULTS: Ratios varied by asbestos type; there were a mean 0.7 (95% confidence interval 0.5, 1.0) asbestos-related lung cancers per mesothelioma death in crocidolite cohorts (n = 6 estimates), 6.1 (3.6, 10.5) in chrysotile (n = 16), 4.0 (2.8, 5.9) in amosite (n = 4) and 1.9 (1.4, 2.6) in mixed asbestos fibre cohorts (n = 31). In a population with 2 mesothelioma deaths per 1000 deaths at ages 40-84 years (e. g., US men), the estimated lung cancer population attributable fraction due to mixed asbestos was estimated to be 4.0%. CONCLUSION: All types of asbestos fibres kill at least twice as many people through lung cancer than through mesothelioma, except for crocidolite. For chrysotile, widely consumed today, asbestos-related lung cancers cannot be robustly estimated from few mesothelioma deaths and the latter cannot be used to infer no excess risk of lung or other cancers. British Journal of Cancer (2012) 106, 575-584. doi: 10.1038/bjc.2011.563 www.bjcancer.com Published online 10 January 2012 (C) 2012 Cancer Research UK