A recent study published in the journal Cancer has found that heavy drinking over a lifetime is linked to an increased risk of colorectal cancer (CRC), particularly rectal cancer, among current drinkers. The research used data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial to analyze how long-term alcohol consumption affects the likelihood of developing both colorectal adenomas—precancerous polyps—and invasive cancer.
The study followed two groups: 12,327 participants who underwent screening for adenomas and 88,092 participants tracked for clinically diagnosed CRC. Researchers collected detailed histories of alcohol intake starting at age 18 and calculated weighted averages across four age ranges.
Participants were categorized by their average weekly alcohol consumption. Those with a lifetime average of 14 or more drinks per week had a 25% higher risk of developing CRC compared to those consuming less than one drink per week (hazard ratio, 1.25; 95% CI, 1.01–1.53). The association was strongest for rectal cancer; heavy drinkers faced nearly double the risk compared to the lowest intake group (hazard ratio, 1.95; 95% CI, 1.17–3.28).
Consistent heavy drinkers throughout adulthood had a 91% higher risk of CRC than consistent light drinkers (hazard ratio, 1.91; 95% CI, 1.17–3.12). Moderate drinking showed a lower risk for some types of CRC but researchers cautioned this could be due to other factors rather than any protective effect from alcohol.
The study also found that former drinkers had significantly lower odds of developing nonadvanced adenomas than current very light drinkers (odds ratio, 0.58; 95% CI, 0.39–0.84), suggesting potential benefits from stopping alcohol use even later in life.
The authors noted that while the results show a strong association between cumulative lifetime alcohol exposure and CRC risk—especially rectal cancer—the observational design means causality cannot be established definitively.
They also highlighted limitations such as reliance on self-reported data and a participant pool that was predominantly white and educated.
Colorectal cancer remains one of the leading causes of cancer deaths in the United States and is ranked third in incidence nationally. While overall rates have declined, cases among adults under age 55 are increasing.
The International Agency for Research on Cancer classifies alcoholic beverages as carcinogenic to humans and links them specifically to colorectal cancer.
This research suggests public health messages should focus not only on immediate health risks but also on the long-term effects of cumulative alcohol intake on cancer development.
