Quitting smoking for 10 years lowers risk of oral cancer by one-third: Study

The study, funded by the Indian Council of Medical Research and involved collaboration between Tata Memorial Centre, Homi Bhabha National Institute, and the University of Oxford, enrolled 2,320 patients with buccal mucosa cancer and 2,302 people without cancer for comparison. Participants were aged between 19 and 75 years, and 88 per cent were men. Regional distribution showed 38 per cent of cases from West India, 36 per cent from North India, 20 per cent from the Northeast, 6 per cent from Central India, and less than 1 per cent from South India.

Socio‑demographic showed that among cancer patients, 28 per cent had less than five years of schooling compared to 9 per cent of people without cancer. Alcohol use was reported by 39 per cent of cancer patients and 23 per cent of people without cancer. Body weight also differed: 10 per cent of cancer patients were underweight and 6 per cent severely underweight, compared to 5 per cent and 1 per cent among people without cancer.

Dr. Dikshit explained that tobacco use patterns showed that 90 per cent of cancer patients chewed tobacco compared to 34 per cent of people without cancer, and 33 per cent of cancer patients smoked compared to 25 per cent of people without cancer. Quitting rates were 39 per cent among smokers and 27 per cent among chewers. Among chewing products, lime tobacco was most common (61 per cent), followed by gutkha (39 per cent), betel quid with tobacco (32 per cent), mawa (6 per cent), and mishri (4 per cent). Among smoking products, 75 per cent used cigarettes and 40 per cent used bidis. Quitting rates varied by product, with 40–42 per cent among cigarette users, 34–38 per cent among bidi users, 39 per cent among gutkha users, and 34 per cent among betel quid users.

Dr. Gayathri B. Pullat, first author of the paper, said, “The evidence is clear, quitting both smoking and chewing tobacco substantially reduces the risk of buccal mucosa cancer. Chewing tobacco with areca nut nearly doubles the cancer risk, but quitting still leads to meaningful risk reduction.”

The study found that current smokers had about six times the risk of developing buccal mucosa cancer compared to neversmokers, while current chewers had more than 21 times the risk. Chewing tobacco with areca nut nearly doubled the danger compared to chewing without it, those who chewed with areca nut were 19 times more likely to develop cancer, while those without were about 10 times more likely.

“Quitting smoking for ten years or more reduced the risk to less than half of current smokers, and quitting chewing for ten years or more reduced the risk to about half of current chewers,” said Dr. Pullat.

The study further showed that risk declines steadily with time: quitting smoking for ten years lowered risk by about one‑third and for 20 years to less than half, while quitting chewing for ten years lowered risk by about one‑quarter and for 20 years by about 40 per cent. Even after a decade of quitting, however, smokers still faced 2.5 times higher risk and chewers 12.5 times higher risk compared to people who never used tobacco.”

Dr Sarayu Mhatre, lead author, said, “Our analysis shows that cessation can reduce the odds of buccal mucosa cancer by up to 62 per cent compared to current users. While never using tobacco remains the safest option, stopping use still provides substantial risk reduction, though the risk does remain higher than in people who have never used tobacco.”

India carries one of the world’s heaviest burdens of oral cancer, accounting for about one‑third of global cases with nearly 141,000 new diagnoses annually, and it ranks among the top three cancers in Indian men. The government has established over 675 tobacco cessation centres under the National Tobacco Control Programme, alongside the National Tobacco Quitline Service (toll‑free number 1800‑11‑2356).

Dr Atul Budukh, professor of Epidemiology, said, “We receive nearly two lakh calls every year on the quitline, but can respond to only about 30 per cent. Of those who receive counselling, around 25 per cent have successfully quit tobacco in the last six years. People with strong family support are more likely to quit, while those without such support often struggle.”