Residential radon and lung cancer risk: an updated meta- analysis of case-control studies.

BACKGROUND: Numbers of epidemiological studies assessing residential radon exposure and risk of lung cancer have yielded inconsistent results. METHODS: We therefore performed a meta-analysis of relevant published case- control studies searched in the PubMed database through July 2011 to examine the association. The combined odds ratio (OR) were calculated using fixed- or random-effects models. Subgroup and dose-response analyses were also performed. RESULTS: We identified 22 case-control studies of residential radon and lung cancer risk involving 13,380 cases and 21,102 controls. The combined OR of lung cancer for the highest with the lowest exposure was 1.29 (95% CI 1.10-1.51). Dose-response analysis showed that every 100 Bq/m3 increment in residential radon exposure was associated with a significant 7% increase in lung cancer risk. Subgroup analysis displayed a more pronounced association in the studies conducted in Europe. Studies restricted to female or non-smokers demonstrated weakened associations between exposure and lung cancer. CONCLUSIONS: This meta- analysis provides new evidence supporting the conclusion that residential exposure to radon can significantly increase the risk of lung cancer in a dose-response manner.