Colorectal cancer: Higher lifetime alcohol intake is linked to a greater risk of colorectal cancer, especially rectal cancer, and people who stop drinking may see their risk fall back toward that of light drinkers, according to new research published in Cancer.
Researchers examined data from 88,092 US adults enrolled in the National Cancer Institute’s Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial who had no cancer at the start of the study. Over roughly 20 years of follow-up, 1,679 participants developed colorectal cancer.
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The analysis found that current drinkers whose average lifetime alcohol use was 14 or more drinks per week were at higher risk than those who averaged fewer than one drink per week. Heavy drinkers had a 25% higher risk of colorectal cancer overall and a 95% higher risk of rectal cancer.
When researchers looked at drinking patterns over time, the risk appeared highest among people who drank heavily throughout adulthood. Consistent heavy drinking was associated with a 91% higher risk of colorectal cancer compared with consistent light drinking.
The study also reported a more encouraging signal for people who quit. Former drinkers did not show evidence of increased colorectal cancer risk in this dataset, and they had lower odds of developing colorectal adenomas, noncancerous growths that can sometimes progress to cancer, than current very light drinkers. The authors noted, however, that the number of former drinkers in the analysis was limited, meaning those findings should be interpreted cautiously.
Researchers said the alcohol–cancer link may be driven by carcinogenic byproducts of alcohol metabolism and potential effects on the gut microbiome, though more work is needed to confirm the biological pathways.
“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,” co–senior author Erikka Loftfield of the NCI said in a statement, adding that while the former-drinker data were sparse, it was encouraging that risk may return toward that seen in light drinkers.
