The impact of tobacco cessation on buccal mucosa cancer risk: A multi-centre case-control study in India.

While the association between tobacco consumption and oral cancer is well established, the effect of tobacco cessation, particularly chewing tobacco, is less extensively studied. We aim to explore the effect of tobacco cessation on the risk of buccal mucosa cancer (BMC). A case-control study was conducted across five cancer centres in India. We enrolled 2320 BMC and 2302 frequency-matched controls. Information was collected on smoking and chewing (products, duration and quitting). Unconditional logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) of the effect of tobacco cessation compared to current users, after adjusting for potential confounders. For both smoking and chewing, the odds reduced rapidly after 5 years of quitting, so that those who had quit smoking ≥10 years ago had only 0.39 (95% CI 0.28-0.54) the odds of BMC compared to those who continued to smoke, and those who quit chewing ≥10 years ago had 0.58 (95% CI 0.43-0.81) the odds of BMC compared to those who continued to chew. Chewing with areca nut was associated with almost double the risk of chewing without (OR 1.86, 95% CI 1.53-2.26) but the rate of reduction of risk with quitting was similar. These findings show clearly the benefits of quitting and inform policies that emphasize chewing tobacco cessation, given its widespread prevalence in India.