Weight-Loss Surgery Linked to About 19% Lower Obesity-Related Cancer Rate in Huge Nordic Study

Weight-loss surgery is associated with a meaningfully lower rate of obesity-related cancers, and the pattern holds for younger as well as middle-aged adults, according to a very large Nordic study published in JAMA Surgery.

Researchers led by Karolinska Institutet examined health registry records for 784,105 people with obesity in Denmark, Finland and Sweden, drawn from national data spanning 1992 to 2023. Of those, 99,614 had undergone bariatric surgery; their later cancer rates were compared with people with obesity who had not had an operation. The study covered adults aged 18 to 59.

Where the lower rates showed up

After statistical adjustment, surgery was associated with about a 19% lower rate of obesity-related cancers overall — a relative difference, not a guarantee for any individual patient. The strongest associations were seen for liver cancer and cancer of the uterine lining, and ovarian cancer also showed a lower rate. Comparing age groups, researchers found similar overall reductions in people aged 18 to 39 and those aged 40 to 59, and no clear difference between women and men for cancers that affect both sexes.

One important exception

The results were not uniformly positive. Pancreatic cancer showed the opposite pattern, with higher rates after surgery, particularly among younger adults. The study cannot explain why that exception occurred.

The researchers also stress the limits of the design: this was an observational registry study, not a randomised trial. People who undergo surgery may differ from those who do not in ways registries cannot fully capture, so the study does not prove that surgery itself caused the lower — or higher — cancer rates. Even so, the authors say the findings, involving first author Cecilia Radkiewicz, strengthen the evidence that treating severe obesity is linked to broad long-term health effects worth weighing carefully.

Source: Knowridge