[A cohort study on risk factors of lung cancer in Yunnan tin miners].

BACKGROUND: Smoking is a major cause of lung cancer. Studies of lung cancer among miners have shown that occupational exposure also played an important role. The aim of this study is to investigate radon, cigarette use and other risk factors of lung cancer in Yunnan tin miners and to provide a scientific basis for the prevention and control of occupational lung cancer. METHODS: A prospective cohort study was conducted among Yunnan tin miners, the associations between potential risk factors for lung cancer were analyzed by multivariate Cox regression model. Effects of age at first radon exposure and radon exposure rate on lung cancer risk were analyzed. The relationship between cumulative working level month and lung cancer was analyzed according to smoking status. The joint effect of tobacco use and cumulative radon exposure was analyzed based on additive and multiplicative models. RESULTS: Increased risk of lung cancer was associated with age at enrollment, tobacco use, prior bronchitis, and cumulative arsenic and radon exposure, while higher education level was associated with decreased lung cancer risk. An inverse effect of radon exposure rate was observed. There was no significant association between lung cancer risk and first radon exposure age. There was a significant additive interaction between tobacco use and radon exposure on lung cancer risk. CONCLUSIONS: Several risk factors may contribute to the high incidence of lung cancer in Yunnan tin miners. Further studies are warranted to evaluate joint effect of different risk factors.