Bariatric surgery may reduce the risk of colon cancer in patients with obesity, according to findings that contradict previous research.

French researchers used national health-insurance data on more than one million patients with obesity, aged 50-75, with no history of colorectal cancer.

They compared more than 74,000 individuals who had undergone bariatric surgery (mean age 57) with more than 971,000 propensity-matched individuals who had not (mean age 63).

Mean follow-up was 5.7 years for patients who had weight-loss surgery, including adjustable gastric banding, sleeve gastrectomy or gastric bypass, and 5.3 years for the no-surgery group.