Reverse smoking in Andhra Pradesh, India: a study of palatal lesions among 10,169 villagers.

In the district of Srikakulam in Andhra Pradesh in South India the habit of reverse smoking is widespread. In a house to house survey of oral cancer and precancerous conditions, comprising 10,169 villagers, 43·8% were reverse smokers; the female: male ratio being 1·7: 1. Ten previously undiagnosed cases of oral cancer, 9 located to palate, were found. The prevalences for leukoplakia, preleukoplakia and leukokeratosis nicotina palati were 4·9%, 2·9% and 9·5%. Of 497 leukoplakias, 422 were located to the palate and 413 of these patients had the habit of reverse smoking. Histologically, 80% of 381 palatal biopsies had a hyperorthokeratosis. Epithelial atypia was found in 15·3% of leukoplakias, in 3·6% of the preleukoplakias, and in 9·1% of leukokeratosis nicotina palati. Various explanations for the habit of reverse smoking are suggested and discussed. In addition to reverse smoking, other tobacco habits were also recorded; all habits and oral lesions were compared and have been discussed according to their apparent interrelationships and distribution by sex and age.