Effect of cessation of tobacco use on the incidence of oral mucosal lesions in a 10-yr follow-up study of 12,212 users.

OBJECTIVE To study the effect of cessation of tobacco use on the incidence of lichen planus, leukoplakia and other oral mucosal lesions. DESIGN A 10-yr cohort study in a rural population of Ernakulam district, Kerala, India. MATERIAL AND METHODS Some 12,212 tobacco users were interviewed and examined in a baseline survey and re-examined annually for 10 years. At each examination they were exposed to health educational programs to encourage them to quit their tobacco use. The incidence rates were calculated using person-years method among those who stopped their tobacco use and all others. RESULTS A total of 77,681 person-years of observation accrued among men and 32,544 among women. Among men 6.5% of these and among women 14.4% were in the stopped category. The incidence of oral lichen planus did not show any consistent association with cessation of tobacco habits (incidence ratio 1.35) but for leukoplakia there was a substantial drop in the incidence after cessation (incidence ratio 0.31). Several other tobacco-associated oral mucosal lesions such as oral lichen planus-like lesion, smoker's palate, preleukoplakia, central papillary atrophy of the tongue and leukoedema showed either zero, or very small incidence, after cessation. CONCLUSION The reported association between tobacco use and lichen planus appears to be indirect but for all other lesions it is direct. The cessation of tobacco use led to a substantial fall in the incidence of leukoplakia and other lesions implying a reduced risk for oral cancer after cessation of tobacco use.