by Erikka Loftfield, PhD, MPH – NIH – January 26, 2026
Key takeaways:
- Consistent heavy alcohol use and higher lifetime consumption may raise risk for colorectal cancer, particularly rectal tumors.
- Data suggest a benefit of alcohol cessation among former moderate/heavy drinkers.
An analysis of more than 88,000 U.S. adults provides new insights into how duration and extent of alcohol consumption may affect colorectal cancer risk.
Current and consistent heavy alcohol intake throughout adulthood appeared associated with a near-doubling of risk compared with current, consistent light drinking, data from a population-based randomized screening trial showed.
Data derived from O’Connell CP, et al. Cancer. 2026;doi:10.1002/cncr.70201.
Higher lifetime alcohol consumption also appeared associated with significantly higher risk, particularly for rectal tumors.
In addition, the findings suggested benefits of alcohol cessation, including lower odds for colorectal cancer or nonadvanced adenomas.
Erikka Loftfield states that “The findings of this study support — and really give empirical weight to — guidance from internationally recognized bodies that recommend limiting or abstaining from alcohol intake to reduce cancer risk,” .
Filling an evidence gap
Research has intensified over the past several years into alcohol’s role in cancer development.
A population-based study led by International Agency for Cancer Research linked alcohol consumption to more than 740,000 new cancer diagnoses in 2020, equivalent to 4% of cases worldwide.
Loftfield and colleagues analyzed data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial — designed to determine the effects of screening on cancer-related mortality among cancer-free adults — to estimate the association between lifetime alcohol consumption and incident colorectal cancer or adenoma.
“Prior studies have established that alcohol consumption is associated with increased risk of cancer, but there’s very little data regarding how lifetime patterns of drinking affect colorectal adenoma and cancer risk,” Loftfield said. “We wanted to try to fill that gap. We know a lot about how smoking cessation lowers cancer risk, but we wanted to learn more about what reduction or cessation of alcohol drinking means for future cancer risk.”
In the PLCO trial, researchers randomly assigned people aged 55 to 74 years to cancer screening or standard care. Colorectal cancer screening consisted of flexible sigmoidoscopy at baseline, and again either 3 years or 5 years later.
Trial participants completed risk factor and dietary history questionnaires. They reported alcohol intake during four age periods —18 to 24 years, 25 to 39 years, 40 to 54 years, and 55 years and older — using 10 predefined frequency categories, as well as current drinking frequency at baseline.
Loftfield and colleagues categorized participants as current drinkers, former drinkers or never drinkers.
They used multiple categories to quantify average lifetime drinking — less than one drink per week, one to less than seven drinks per week, seven to less than 14 per week, or 14 or more per week — and they used past and current drinking frequency to define broader alcohol intake patterns through adulthood.
They used sex-specific U.S. dietary guidelines to classify light drinking (less than 14 drinks per week for men, less than seven per week for women), moderate drinking (14 to 21 drinks per week for men, seven to 14 per week for women) and heavy drinking (22 or more per week for men, 15 or more per week for women).
‘Timely’ findings
During 20 years of follow-up, 1,679 incident colorectal cancer cases occurred among 88,092 PLCO trial participants.
Current drinkers who had an average lifetime alcohol intake of 14 or more drinks per week exhibited a 25% (HR = 1.25; 95% CI, 1.01-1.53) higher risk for colorectal cancer than those with average lifetime intake of one drink or less per week.
Those with higher average lifetime alcohol intake had nearly double the risk for rectal cancer (HR = 1.95; 95% CI, 1.17-3.28).
“This finding is timely because we are seeing increasing rates of colorectal cancer among younger people, and that increase has been driven predominantly by rectal tumors,” Loftfield said.
Consistent heavy drinking appeared associated with a near-doubling of colorectal cancer compared with light drinking (HR = 1.91; 95% CI, 1.17-3.12).
The data also suggested benefits of alcohol cessation.
Former drinkers who had been moderate to heavy drinkers earlier in life exhibited similar colorectal cancer risk as light drinkers.
An analysis of about 12,000 PLCO trial participants who had negative baseline screens compared former drinkers with current drinkers who averaged less than one drink per week in their lifetime. Results showed former drinkers had numerically lower risk for any adenoma (OR = 0.78; 95% CI, 0.59-1.02) and significantly lower risk for nonadvanced adenoma (OR = 0.58; 95% CI, 0.39-0.84).
“From a clinical perspective, that is pretty robust evidence to support that there is a benefit to drinking cessation,” Loftfield said.
The mechanisms of alcohol’s impact on cancer risk have been well studied, specifically related to how alcohol in the body converts to acetaldehyde, a known carcinogen. Less is known about how alcohol affects the gut microbiome and the impact that may have on colorectal cancer risk, Loftfield said.
Loftfield and colleagues hope to conduct additional research exploring the impact of lifetime alcohol use — and alcohol cessation — on other malignancies, such as liver cancer.
Further study into the effects of alcohol cessation on people who average one to two drinks per day also could be valuable, Loftfield said.
“We know a lot more about heavy drinkers who quit drinking or reduce their alcohol intake,” she said. “A better understanding of what happens for moderate drinkers, and how their biology changes when they reduce or quit drinking, may help inform what we know about cancer prevention.”
Source: Herschel Baker – International Liaison Director, Queensland Director, Drug Free Australia