Correlation between chewing and smoking habits and precancerous lesions in hill tribes of northern Thailand.

In a field study, 1866 people from different hill tribes (Lahu, Karen, Lisu and Meo) of northern Thailand and a group of rural Thai were examined for chewing, smoking and drinking habits and precancerous lesions of the oral mucosa. Traditional chewing and smoking habits were more prevalent among older people; cigarette smoking, in contrast, was more prevalent in younger and middle-aged individuals. Preleukoplakia was observed in 1.8%, leukoplakia in 1.1% and chewer's mucosa in 13.1% of the study population. Men and older patients were affected more frequently; chewer's mucosa was seen more often in women (Karen, Thai). A correlation between precancerous lesions and some oral habits could be demonstrated statistically.