Results from a cancer screening trial indicate that consistent heavy alcohol intake and higher average lifetime drinking are associated with increased risk.
Studies have demonstrated a link between alcohol consumption and an elevated risk of colorectal cancer. New research now reveals that higher lifetime alcohol consumption is also associated with a higher risk, especially for rectal cancer, and that quitting drinking can lower a person's risk. The findings are published by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society.
When investigators analyzed data on US adults enrolled in the National Cancer Institute (NCI) Prostate, Long, Colorectal, and Ovarian (PLCO) Cancer Screening Trial who did not have cancer at baseline, they observed that 1,679 colorectal cancer cases occurred among 88,092 participants over 20 years of follow-up.
Current drinkers with an average lifetime alcohol intake of ≥14 drinks per week (heavy drinkers) had a 25% higher risk of developing colorectal cancer and a 95% higher risk of developing rectal cancer compared with those with an average lifetime alcohol intake of <1 drink per week (light drinkers).
When further considering drinking consistency, heavy drinking throughout adulthood was linked to a 91% higher risk of colorectal cancer compared with consistent light drinking. In contrast, no evidence of increased colorectal cancer risk was observed among former drinkers, and former drinkers had lower odds of developing noncancerous colorectal tumors, or adenomas (which may go on to become cancerous) than current drinkers averaging <1 drink per week, suggesting that alcohol cessation may lower individuals' risks. These data were limited, however.
The association between alcohol consumption and increased risks observed in this and other studies might be explained by carcinogens produced from alcohol metabolism or alcohol's effects on gut microbes. Additional studies are needed to test whether these mechanisms are involved.
"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. While the data on former drinkers were sparse, we were encouraged to see that their risk may return to that of the light drinkers," said co-senior author Erikka Loftfield, PhD, MPH, of the NCI, part of the National Institutes of Health.
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