Korean scientists have conducted the first major study showing how the frequency of drinking alcohol affects the risk of developing cancer. It is published in JAMA Network Open.
The International Agency for Research on Cancer considers alcohol a carcinogen. However, scientists have so far little studied the relationship between drinking regimen and cancer risk. Previously, research has focused primarily on the total amount of alcohol people drink in a given amount of time. In such works, no distinction is made between a person who drinks one mug of beer a day for a week and a person who empties seven mugs in one sitting once a week.
Korean scientists decided to find out how the frequency of alcohol consumption affects the risk of cancer. To do this, they used the national health insurance database. They analyzed data on more than 11 million people who participated in the Korean National Health Screening Program in 2009-2010. None of them had cancer at the start of the follow-up.
Participants were followed up for an average of 6.4 years. Cancer of the esophagus, stomach, intestines, liver or pancreas developed in 2.7% of them. Compared to non-drinkers, people who drank little (up to 100 grams of alcohol per week) were 4% more likely to develop one of these cancers. In moderate drinkers (up to 200 grams), it increased by 14%, a lot — by 28%.
The risk of cancer increased proportionally with the frequency of drinking. For those who drank daily, it was 39% higher than for non-drinkers. At the same time, the effect of the amount of alcohol consumed on cancer risk was limited. For those who drank from five to seven servings at a time, it was maximum, but did not increase with a further increase in the dose.
Scientists believe that doctors, when interviewing patients, should not focus only on the amount of alcohol that they consume. Regular drinking, even in small quantities, plays a big role.
The authors of the study write that Koreans may be more susceptible to the carcinogenic effects of alcohol than people of other nationalities.
In a comment Professor John Potter of Massey University pointed out to the study that this work indicates a causal relationship between alcohol consumption and malignant tumors of the digestive system.