Oral cancer and precancer related to betel and miang chewing in Thailand: a review.

Historical aspects of betel and miang chewing in Thailand are described, as is the betel quid. Available literature on cancer and precancer in Thailand is reviewed. While oral cancer has been a major health problem in the past, changes in habit patterns with marked reduction of betel and miang chewing during the last decades have prompted a change in frequency of oral cancer in some provinces. Oral effects of miang chewing are less marked, although chewer's mucosa has been observed. Betel and miang chewing seem to be vanishing habits in Thailand in contrast to other Southeast Asian or South Asian countries.