Environmental determinants of lung cancer in Shenyang, China.

To investigate determinants of the high rates of lung cancer in Shenyang, an industrial city in north-eastern China, a case-control study was conducted. Interviews with 1249 lung cancer patients and 1345 population-based controls revealed that cigarette smoking was the main cause of lung cancer. Smoking accounted for 55% of the lung tumours in men and 37% in women. In addition, air pollution from coal-burning heating and cooking devices was significantly linked to lung cancer, with risks rising in proportion to duration of exposure to indoor pollutants. Measurement of benzo[a]pyrene revealed average wintertime levels in air that were nearly 60 times the recommended upper limit for US cities, with even higher concentrations indoors in traditional single-storey homes using coal-burning kang (stoves). Occupational factors were also involved, the risk being elevated by three fold among smelter workers. Soil levels of arsenic and other metals rose with increasing proximity to the Shenyang copper smelter, and elevated risks of lung cancer were found among men, but not women, living within 1 km of its central stacks. Prior nonmalignant lung disease was common and was reported more often among the lung cancer patients than among controls. The findings suggest that cigarette smoking and environmental pollutants combine to account for most of the excess risk of lung cancer in this population.