How does lifetime alcohol consumption affect colorectal cancer risk?

Erikka Loftfield

28.01.2026 - A large U.S. cancer screening trial shows that consistent heavy drinking across adulthood and higher average lifetime alcohol intake significantly increase the risk of colorectal cancer — especially rectal cancer. Importantly, people who quit drinking did not show elevated risk, suggesting that stopping alcohol use may help reduce long‑term cancer risk.

Researchers analyzed 20 years of follow‑up data from 88,092 adults in the National Cancer Institute’s PLCO Cancer Screening Trial. During this period, 1,679 colorectal cancer cases were identified.

Major findings:

• Heavy lifetime drinkers (≥14 drinks/week) had:

  • 25% higher risk of colorectal cancer

  • 95% higher risk of rectal cancer compared with people drinking <1 drink/week.

• Consistent heavy drinking throughout adulthood was linked to a 91% higher risk of colorectal cancer.

• Former drinkers did not show increased risk and had lower odds of adenomas (precancerous tumors) than current light drinkers.

• These results suggest that alcohol cessation may help lower risk, though more data are needed.

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🧬 Why alcohol may increase risk

The study notes two likely biological explanations:

• Carcinogenic by‑products of alcohol metabolism

• Alcohol’s impact on gut microbiota

Further research is needed to clarify these mechanisms.

Co–senior author Erikka Loftfield, PhD, MPH (National Cancer Institute) highlighted that this is one of the first studies to examine alcohol use across the life course in relation to both adenomas and colorectal cancer. She noted encouraging signs that risk among former drinkers may return to the level of light drinkers.

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📚 Study Reference

O’Connell CP, Berndt SI, Chudy-Onwugaje K, Kunzmann A, Huang W‑Y, Barry KH, Loftfield E. “Associations of alcohol intake over the lifetime with colorectal adenoma and colorectal cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.”   CANCER. Published online January 26, 2026. DOI: 10.1002/cncr.70201.