Even a low daily intake of alcohol – as little as 9g or about a standard drink – is associated with a 50% increased risk of oral (lining of the mouth) cancer in India, with the greatest risk associated with local alcohol, finds a large comparative study, published online in the open access journal. BMJ Global Health.
And when combined with chewing tobacco, it likely accounts for 62% of all such cases in India, the findings suggest.
Oral cancer is the second most common malignancy in India, with 143,759 new cases and 79,979 deaths each year. Rates of the disease have been rising steadily and are now just under 15 for every 100,000 Indian men, the researchers note.
The main form of oral cancer in India is that of the pale pink lining of the cheeks and lips (oral mucosa). Less than half (43%) of those affected survive 5 years or more, they point out.
Because alcohol consumption and tobacco use often go hand in hand, it is unclear how much each factor individually contributes to oral cancer risk, especially in India, where the prevalence of smokeless tobacco use is high, the researchers point out. Nor has the potential impact of locally brewed alcohol, which is particularly popular in rural communities, been assessed, they add.
To learn more, researchers compared 1,803 people with confirmed oral mucosal cancer and 1,903 randomly selected people without the disease (controls) from five different study centers between 2010 and 2021. Most of the participants were between the ages of 35 and 54. almost half (about 46%) of the cases were between 25 and 45 years of age.
Each participant provided information on the duration, frequency and type of alcohol they drank from 11 internationally recognized beverages including beer, whiskey, vodka, rum and breezers (flavoured alcoholic drinks). and 30 locally brewed drinks including apong, bangla, chulli, desi daru and mahua.
Participants were also asked about the duration and type of tobacco use, so that the extent of the interaction between alcohol and tobacco on oral cancer risk could be assessed.
Among the cases, 1019 said they did not drink alcohol compared with 1420 among the controls. 781 of the cases said they drank alcohol compared to 481 of the controls.
The mean duration of tobacco use was longer for cases (about 21 years) than for controls (about 18 years). Cases were also more likely to live in rural areas and drink more alcohol each day: almost 37g compared to around 29g.
Frequent alcohol consumption was associated with an increased risk of oral mucosal cancer, with locally brewed beverages associated with the greatest risk.
Compared to those who did not drink alcohol, the risk was 68% higher for those who drank, rising to 72% for those who preferred internationally recognized types of alcohol and 87% for those who chose local drinks.
Less than 2 ga of beer per day was associated with an increased risk of oral mucosal cancer. And just 9 g/day of alcohol – equivalent to about one standard drink – was associated with about a 50% increased risk.
Concomitant use of alcohol and tobacco was associated with a more than fourfold increase in risk, so that 62% of all oral cancer cases in India are likely attributable to the interaction between alcohol and chewing tobacco, the researchers estimate.
But alcohol was a factor that contributed to the increased risk of oral cancer, regardless of how long tobacco had been used. Ethanol may alter the fat content of the lining of the mouth, increasing its permeability and thus its sensitivity to other potential carcinogens in chewing tobacco products, the researchers explain.
The findings suggest that more than 1 in 10 cases (nearly 11.5%) of all oral cancers in India are attributable to alcohol, rising to 14% in some of the states with a high prevalence of the disease, such as Meghalaya, Assam and Madhya Pradesh, the researchers say.
Potential contamination with toxins, such as methanol and acetaldehyde, in locally brewed alcohol may explain the higher risk associated with these drinks, whose manufacture is largely unregulated, they suggest.
“The current legal framework for alcohol control in India is complex and includes central and state laws. Central legislation provides protection to citizens where alcohol is included in the State list under the Seventh Schedule of the Indian Constitution, giving states the power to regulate and control the production, distribution and sale of alcohol. However, the local liquor market is unregulated, with certain forms being used by participants.
They conclude: “In summary, our study shows that there is no safe limit of alcohol consumption for [buccal mucosa cancer] risk…Our findings suggest that public health action to prevent alcohol and tobacco use could largely eliminate [buccal mucosa cancer] from India”.
