Tobacco habits and risk of lung, oropharyngeal and oral cavity cancer: a population-based case-control study in Bhopal, India.

BACKGROUND Tobacco habits in India are unique and vary in different regions. Few studies, and none from central India, have reported on type of tobacco used and risk of the most common cancer types in India. We conducted a population-based case-control study to evaluate the risk of tobacco particularly bidi smoking and tobacco quid chewing on the most common cancer sites among males in Bhopal. METHODS In all, 163 lung, 247 oropharyngeal and 148 oral cavity cancer cases from the Population-Based Cancer Registry records and 260 controls randomly selected from a tobacco survey conducted in the Bhopal population formed the study population. RESULTS A significant risk of bidi and cigarette smoking with a dose-response relationship was observed for lung and oropharyngeal cancer. Tobacco quid chewing showed no risk for lung, marginally increased risk for oropharyngeal and about a sixfold increased risk for oral cavity cancer. Population-attributable risk per cent (PARP) was observed to be 82.7% and 71.6% for smokers for the development of lung and oropharyngeal cancer, while the same was found to be 66.1% for tobacco chewers for the development of oral cavity cancer. CONCLUSIONS These data provide strong evidence that smoking bidi is even more hazardous than cigarette smoking in the development of lung and oropharyngeal cancer. An intervention study to prevent the use of tobacco will be useful in this population as it also underwent gas exposure due to a chemical accident in 1984.