Precancerous and other oral mucosal lesions related to chewing, smoking and drinking habits in Thailand.

In a field study (1979-1984) four out of six major hilltribes of Northern Thailand, namely the Lahu, Karen, Lisu and Meo, as well as a group of rural Thai, were examined. Chewing, smoking and drinking habits and lesions of the oral mucosa (leukoedema, preleukoplakia, leukoplakia and chewer's mucosa) were recorded. 1866 individuals were examined. Considerable differences in the chewing and smoking habits among the various tribes were recorded and some of them were considered tribe-specific. Chewing of betel and miang was more prevalent among older people; these habits seem to have lost their attraction for the younger people. Cigarette smoking was more prevalent among middle-aged individuals. Leukoedema was observed in 12.4%, preleukoplakia in 1.8%, leukoplakia in 1.1% and chewer's mucosa in 13.1%. Men and the older generation were affected more often, except that more women (Karen and Thai) revealed chewer's mucosa. A positive correlation could be demonstrated between some mucosal lesions (leukoedema, chewer's mucosa) and some smoking and chewing habits.