Between 1996 and 1999 we carried out a case-control study in 3 areas in Southern India (Bangalore, Madras and Trivandrum) including 591 incident cases of cancer of the oral cavity (282 women) and 582 hospital controls (290 women), frequency-matched with cases by age and gender. Odds ratios (ORs) and 95% confidence intervals (CIs) were obtained from unconditional multiple logistic regressions and adjusted for age, gender, center, education, chewing habit and (men only) smoking and drinking habits.
Key words: oral cancer; tobacco; paan chewing; alcohol; oral hygieneCancer of the oral cavity and pharynx is the first and third commonest cancer in Indian men and women, respectively. 1 Whereas in most areas at high risk for cancer of the oral cavity other than India (e.g., central and Eastern Europe, South America), the ratios between male and female incidence rates range between 3 and 10, in India the male-to-female ratio is approximately 1 (e.g., Madras) or lower than 0.5 (Bangalore). 2 Such very high incidence rates in Indian women reflect the persistent importance in India of paan chewing, a habit that is equally common in the 2 genders. 3 Paan generally includes calcium hydroxide, areca nut (from the Areca catechu tree) and betel leaf (from the Piper betle vine). Tobacco and/or various spices are commonly added. 4 Paan represents a cheap pharmacologically addicting stimulant, principally used by members of low social classes in South Asia. Fewer efforts have been made in Asia to discourage paan chewing than tobacco smoking, 5 and only recently have links been established between paan and oral cancer that cannot be explained by the presence of tobacco. 3,6 Annual per capita consumption of cigarettes in India was maximal in the 1970s and 1980s and declined by approximately 40% in the early 1990s. 7 Two nation-wide surveys 8,9 showed a somewhat lower prevalence of tobacco use in any form in 1993-1994 (23% in urban and 34% in rural areas in men and 4% and 9%, respectively, in women) than in 1987-1988 (26% and 35% in men and 6% and 11% in women, respectively). It is estimated that 150 million males and 34 million females used tobacco in India in 1996. 8,9 Relatively few case-control studies have recently addressed the impact of paan chewing and smoking on oral cancer in India, 10 -12 and information on women and on risk factors other than smoking or chewing is scanty. 12 The present case-control study was conducted in 3 areas of Southern India in order to evaluate the relative importance of smoking, alcohol drinking and paan chewing, with or without tobacco, on cancer of the oral cavity in men and women and the modifying effect, if any, of various indicators of oral hygiene. Our study is part of an international study on oral cancer coordinated by the International Agency for Research on Cancer and carried out also in Italy,