Alcohol consumption can directly cause cancer, new genetic study finds

A large genetic study involving 150,000 subjects over more than a decade confirmed the direct causal link between alcohol consumption and the development of cancer. The results notably associate esophageal and head and neck cancers with alcohol consumption.

Although researchers have been highlighting associations between alcohol consumption and cancer for many years, it has been difficult to understand exactly how directly alcohol causes cancer, as opposed to the many style factors of harmful life that often coincides with the consumption of alcohol.

Heavy alcohol consumption is often associated with poor diet, smoking and lack of exercise – all factors known to increase cancer risk. Thus, some have suggested that it is these factors that primarily explain any observed correlation between alcohol consumption and cancer.

This new study took a novel approach to studying the alcohol-cancer link by focusing on genetic variants known to be associated with lower levels of alcohol consumption.

Two common genetic variants are known to reduce a person’s tolerance to alcohol. They decrease a person’s ability to break down acetaldehyde, a toxic molecule produced when the body metabolizes alcohol. Previous studies have shown that the presence of these genetic variants serve as an effective proxy for alcohol consumption, as people with the mutations generally find the effects of alcohol consumption very unpleasant.

The study looked at the genetic data of 150,000 Chinese subjects. The cohort completed several surveys describing their drinking habits and their general health records were tracked for over a decade. Evaluation of subjective drinking habits confirmed that subjects with the low alcohol tolerance genes consumed significantly less alcohol than those without the genetic variants.

In general, subjects with one or two copies of either genetic variant had between 13 and 31 percent lower risk of cancer. In particular, cancers previously known to be alcohol-related, such as the head and neck, esophagus, colon, rectum, and liver, were detected at high rates in people who drank more alcohol. alcohol.

Further affirming causation, research found that those who had at least one copy of a low alcohol tolerance variant and who still drank alcohol regularly had significantly higher rates of head cancers. and neck and esophageal cancers. This indicates that the inability to break down acetaldehyde may be directly linked to an increased risk of cancer.

“These results indicate that alcohol directly causes several types of cancer and that these risks may be further increased in people with inherited low alcohol tolerance who cannot properly metabolize alcohol,” explained the lead researcher. of the project, Pek Kei.

A landmark 2018 study by researchers at the University of Cambridge directly demonstrated how increased levels of acetaldehyde can directly damage DNA. These findings offered a plausible mechanism to show how alcohol consumption can lead to cancer, especially in people unable to eliminate acetaldehyde effectively.

Darren Griffin, a geneticist from the University of Kent, called the new findings “strong” and said they were backed up by excellent data. He also pointed out that this link between alcohol and cancer is just one of the many ways that alcohol can harm a person’s health.

“The study design inherently isolates the fact that it is alcohol consumption (and not other lifestyle factors) that appears to cause cancer,” said Griffin, who did not work. on this ongoing study. “Studies like these have far-reaching implications for lifestyle choices, however, there are a range of other ways alcohol can harm health.”

Other researchers commenting on the new findings are cautious and note that the genetic variants studied are found primarily in Asian populations, so more work is needed to validate the association in European populations. Stephen Burgess, a statistician from the University of Cambridge, pointed to this limitation while calling for more research into this association in other ethnicities.

“One of the limitations of this investigation is that the harmful effect of alcohol on cancer appears to be strongest in people who cannot break down alcohol effectively.” said Burgess. “The inability to break down alcohol effectively is a common trait in East Asian populations, but is less common in populations of European ancestry. Further research is needed to determine whether a similar harmful effect alcohol on cancer exists in populations of European descent.

The new findings build on a strong body of evidence linking alcohol to an increased risk of cancer. A striking study last year from the International Agency for Research on Cancer estimated that around 740,000 new cancer cases in 2020 could be directly attributed to alcohol consumption. This represents approximately four percent of all cancer cases worldwide.

The new study has been published in the journal International Journal of Cancer.

Source: Oxford Population Health

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