A new study tracking U.S. adults over two decades links heavy lifetime alcohol consumption to increased colorectal cancer risk, particularly for rectal cancer. Heavy drinkers faced up to a 95% higher risk compared to light drinkers, but former drinkers showed no elevated risk. The findings suggest quitting alcohol could reduce long-term cancer chances.
Researchers from the National Cancer Institute analyzed data from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, involving 88,092 cancer-free U.S. adults followed for 20 years. During this period, 1,679 participants developed colorectal cancer.
Heavy drinkers, defined as those averaging at least 14 drinks per week over their lifetime, had a 25% higher risk of colorectal cancer than those averaging fewer than one drink per week. The risk was even steeper for rectal cancer, nearly doubling with a 95% increase. Among those who drank heavily throughout adulthood, the colorectal cancer risk rose by 91% compared to consistent light drinkers.
In contrast, former drinkers did not exhibit an increased cancer risk and had lower odds of developing adenomas—precancerous colorectal tumors—than light current drinkers. This indicates potential benefits from stopping alcohol use, though data on former drinkers was limited.
The study, published online in the journal Cancer by Wiley, highlights how cumulative alcohol intake influences cancer development. Possible mechanisms include harmful byproducts from alcohol metabolism or its effects on gut bacteria, but further research is needed.
"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.
These results build on prior evidence tying alcohol to colorectal cancer, emphasizing lifetime patterns over occasional use.
