Even one drink a day may raise mouth cancer risk

When alcohol use occurred alongside chewing tobacco, the combined effect was especially severe. Researchers estimate that this pairing may be responsible for 62% of all mouth (buccal mucosa) cancer cases in the country.

Mouth Cancer Rates Continue to Climb in India

Mouth cancer ranks as the second most common cancer in India, with an estimated 143,759 new diagnoses and 79,979 deaths each year. According to the researchers, incidence rates have steadily increased and now sit just below 15 cases per 100,000 Indian men.

The most common form affects the soft pink tissue lining the cheeks and lips (buccal mucosa). Survival outcomes remain poor, with only 43% of patients living five years or longer after diagnosis.

Untangling the Roles of Alcohol and Tobacco

Alcohol use and tobacco consumption frequently occur together, making it difficult to separate their individual effects on mouth cancer risk. This is particularly true in India, where smokeless tobacco use is widespread, the researchers note. They also point out that the health effects of locally brewed alcohol, which is especially common in rural areas, have received little attention until now.

To better understand these risks, the researchers compared 1,803 people diagnosed with buccal mucosa cancer with 1,903 randomly selected individuals without the disease (controls). Participants were recruited from five study centers between 2010 and 2021. Most were between 35 and 54 years old, and nearly 46% of cancer cases occurred among people aged 25 to 45.

Tracking Drinking Habits and Tobacco Use

Participants provided detailed information about how long they had been drinking alcohol, how often they drank, and the types of alcohol they consumed. This included 11 internationally recognized drinks such as beer, whisky, vodka, rum and breezers (flavored alcoholic drinks), along with 30 locally brewed options including apong, bangla, chulli, desi daru, and mahua.

They were also asked about their tobacco use, including duration and type, allowing researchers to examine how alcohol and tobacco interact to influence mouth cancer risk.

Among those with cancer, 781 reported drinking alcohol, while 1,019 said they did not. In the control group, 481 drank alcohol and 1,420 did not.

Higher Exposure Linked to Greater Risk

People with buccal mucosa cancer reported longer tobacco use on average, about 21 years compared with roughly 18 years among the control group. They were also more likely to live in rural areas and to consume larger amounts of alcohol each day, nearly 37 g compared with about 29 g.

Frequent alcohol consumption was strongly associated with increased cancer risk, with locally brewed drinks showing the greatest effect.

Compared with people who did not drink alcohol, those who did had a 68% higher risk of developing buccal mucosa cancer. The risk rose to 72% among individuals who favored internationally recognized drinks and climbed to 87% among those who consumed locally brewed alcohol.

No Safe Threshold Identified

Even very small amounts of alcohol appeared to matter. Drinking less than 2 g of beer per day was still linked to an increased risk of buccal mucosa cancer. Consuming 9 g of alcohol daily, roughly one standard drink, was associated with an approximately 50% higher risk.

Using alcohol and tobacco at the same time produced a dramatic effect. The combined exposure was linked to more than a fourfold increase in risk. Based on their calculations, the researchers estimate that 62% of buccal mucosa cancer cases in India are attributable to the interaction between alcohol and chewing tobacco.

How Alcohol May Increase Vulnerability

Alcohol increased mouth cancer risk regardless of how long a person had used tobacco. The researchers suggest that ethanol may change the fat content of the mouth's inner lining, making it more permeable and more susceptible to carcinogens found in chewing tobacco products.

Overall, the analysis indicates that more than one in ten buccal mucosa cancer cases in India, nearly 11.5%, can be attributed to alcohol consumption. In states with particularly high disease rates, including Meghalaya, Assam, and Madhya Pradesh, that proportion rises to about 14%.

Concerns About Unregulated Local Alcohol

The higher risk associated with locally brewed alcohol may be partly due to contamination with toxic substances such as methanol and acetaldehyde. The researchers note that production of these drinks is largely unregulated.

"The current legal framework for alcohol control in India is complex and involves both central and state laws. Central legislation provides protection of 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 alcohol production, distribution and sale. However, the locally-brewed liquor market is unregulated, with some forms used by participants containing up to 90% alcohol content," they point out.

Implications for Prevention

They conclude: "In summary, our study demonstrates that there is no safe limit of alcohol consumption for [buccal mucosa cancer] risk…Our findings suggest that public health action towards prevention of alcohol and tobacco use could largely eliminate [buccal mucosa cancer] from India."