Feasibility of conducting a lung-cancer chemoprevention trial among tin miners in Yunnan, P. R. China

Abstract

Tin miners in Yunnan Province in southern China have an extremely high rate of lung cancer, more than one percent per year among those at 'high risk' (40+ years old, with 10+ years of underground mining and/or smelting experience). The extraordinary lung cancer rates result from combined exposure to radon, arsenic, and tobacco smoking (cigarettes and/or bamboo water pipe). A study to determine the feasibility of conducting a large-scale, lung-cancer chemoprevention trial was conducted in 1986 among currently employed or retired miners from the Yunnan Tin Corporation in the city of Gejiu. The study was designed to answer four questions: (i) Could potentially eligible miners be identified and recruited? (ii) Could intervention agents be shipped successfully from the United States to the study area and be appropriately distributed? (iii) Would miners adequately adhere to the study protocol and comply with the intervention regimen? (iv) Could potential adverse effects be monitored and documented? The six-month feasibility study yielded affirmative answers to each of these questions. A roster of over 7,000 high-risk miners was compiled. Four agents (vitamin A, 25,000 IU; beta-carotene, 50 mg; vitamin E, 800 IU; and selenium, 400 micrograms) were administered daily with placebos to 350 miners according to a 2(4) factorial design. Adherence, assessed by pill counts and serum micronutrient levels, was approximately 90 percent. The findings from this preliminary study indicate that a full-scale, lung-cancer chemoprevention trial in this population is feasible.