Three decades of data link heavy drinking to increased cancer risk

A study has linked long-term alcohol consumption to a higher risk of colorectal and rectal cancer. Investigating lifetime consumption, the data showed the risk was especially high for current and heavy drinkers when compared to light or non-drinkers. It was also higher when heavy drinking occurred consistently during adulthood.

The study used data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, a trial initiated in 1993 by the National Cancer Institute (NCI) and ended data collection in 2022.

“Our study is one of the first to explore how drinking alcohol over the life course relates to both colorectal adenoma and colorectal cancer risk,” says Erikka Loftfield, co-senior author of the study and a principal investigator at the NCI.

“While the data on former drinkers were sparse, we were encouraged to see that their risk may return to that of the light drinkers.”

Measured throughout life

The study, published in Cancer, used the NCI trial data from 12,327 participants. 

Alcohol consumption was measured across four age groups: 18 to 25, 26 to 39, 40 to 54, and 55 and above, and participants were classified as past or current drinkers.

The study found that consistent heavy drinking throughout life was positively associated with colorectal cancer risk.

Current drinkers who consume 14 or more drinks per week throughout life have a 95% higher risk of rectal cancer, the study says.Current drinkers who consume 14 or more drinks per week throughout life have a 25% higher risk of developing colorectal cancer and a 95% higher risk of rectal cancer, when compared to those who drink one or fewer drinks per week.

The researchers also found that if drinking heavily and consistently during adulthood, there is a 91% increased risk of colorectal cancer.

Previous studies have also linked alcohol to an increased risk of developing colorectal, colon, and rectal cancers.

The new study suggests that stopping drinking may lower the risk of developing adenoma — benign tumors that may become cancerous if not treated. Former drinkers may have a lower risk of developing adenomas than current light drinkers who consume one or no drinks per week.

However, the researchers say that further research is needed to confirm whether quitting drinking reduces the risk, as the data is limited.

There are also other factors that could play a significant role, such as carcinogens in alcohol, causing DNA mutation and oxidative stress in the colon and rectum. Alcohol also affects the gut microbiome, which may result in altered host cell proliferation and death, as well as impact the immune system.

The researchers also note that moderate drinking might reduce inflammation or DNA damage, although it cannot be concluded. This relationship has been previously explored by researchers speaking with Nutrition Insight about the data gap and how wine may affect the gut microbiota, including when consumed with food.