Ethnic Variation in Consumption of Traditional Tobacco Products and Lung Cancer Risk in Nepal

Lung cancer is the leading contributor to cancer deaths in the developing world. Within countries, significantvariability exists in the prevalence of lung cancer risk, yet limited information is available whether some of theobserved variability is associated with differences in the consumption pattern of local tobacco products withdiffering potency. We recruited 606 lung cancer cases and 606 controls from the B.P. Koirala Memorial CancerHospital in Nepal from 2009-2012. We estimated odds ratios (ORs) and 95% confidence intervals (CI) for lungcancer risk associated with different tobacco products, using unconditional logistic regression. Unfiltered cigarettestended to be the most frequently used products across ethnic subgroup with about 53.7% of Brahmins, 60.1% ofChettris, and 52.3% of Rai/Limbu/Magar/others. In contrast, about 39.9% of Madishe/Tharu smokers reportedusing bidi compared with only 27.7% who smoked unfiltered cigarettes. Among those who only smoked one typeof product, choor/kankat smokers had the highest lung cancer risk (OR 10.2; 95% CI 6.2-16.6), followed by bidismokers (OR 5.6; 95% CI 3.6-8.7), unfiltered cigarettes (OR 4.9; 95% CI 3.4-7.2), and filtered cigarettes (OR 3.4;95% CI 2.2-5.3). A clear dose-response relationship was observed between increased frequency of smoking andlung cancer risk across all ethnic subgroups. These results highlight the important role of traditional tobaccoproducts on lung cancer risk in the low income countries.