Obesity drives a substantial share of cancer worldwide, and bariatric surgery is the most effective durable treatment for severe obesity. A large Nordic registry-based study led by researchers at Karolinska Institutet, published online in JAMA Surgery, now shows that the operation's protective association with cancer holds broadly: patients who underwent bariatric surgery had a 19 per cent lower risk of obesity-related cancers than comparable patients who did not, an adjusted incidence rate ratio of 0.81.
The protection was strongest for the cancers most tightly linked to metabolic dysfunction. Liver cancer risk was 51 per cent lower, endometrial cancer 49 per cent lower and ovarian cancer 27 per cent lower among surgical patients. Crucially for clinical decision-making, the association was essentially identical in younger adults aged 18 to 39 and those aged 40 to 59, and similar in women and men, suggesting no demographic group should be assumed to benefit less.
One signal ran the other way: pancreatic cancer risk was higher after surgery, particularly in younger adults, and the authors, led by Cecilia Radkiewicz of Karolinska Institutet and Karolinska University Hospital, call for further research into possible mechanisms. The study, Bariatric Surgery and Risk of Obesity-Related Cancer by Age and Sex, adds long-horizon cancer outcomes to the evidence base clinicians weigh when counselling patients about surgery.