Lower cancer risk after obesity surgery regardless of age or sex
Bariatric surgery reduces the risk of obesity-related cancer regardless of sex and age, according to a large Nordic registry study led by researchers at Karolinska Institutet. The results, published in JAMA Surgery, strengthen knowledge about the cancer-preventive effects of bariatric surgery for several cancers linked to obesity.
Several cancers linked to obesity, particularly gastrointestinal cancers, are increasing in Western populations. Previous research has suggested that obesity surgery reduces the risk of obesity-related cancers, but the association has appeared stronger among women, and findings for several individual gastrointestinal cancer types have been inconsistent. Whether the cancer-preventive effects of obesity surgery differ according to age at surgery remains largely unexplored.
In a large Nordic registry-based cohort study, researchers at Karolinska Institutet and collaborating institutions investigated how obesity surgery affects the risk of obesity-related cancers and whether the association differs depending on age at surgery or between women and men.
The study included more than 780,000 individuals with obesity in Sweden, Denmark, and Finland. Of these, nearly 100,000 had undergone obesity surgery. The researchers found that individuals who underwent surgery had an approximately 20 percent lower risk of developing obesity-related cancer compared with individuals with obesity who did not undergo surgery.
“We found that the reduction in cancer risk after obesity surgery was similar across age groups and between women and men, suggesting that the long-term health benefits of surgery extend to a broad range of patients,” says Cecilia Radkiewicz, researcher at the Department of Molecular Medicine and Surgery, Karolinska Institutet, and first author of the study.
The largest risk reductions were observed for liver, endometrial, and ovarian cancers. The results showed no evidence that the cancer-preventive effect of surgery differed between individuals undergoing surgery at younger versus older ages. For cancers that occur in both women and men, there were also no differences between the sexes.
The results suggest that the long-term cancer-preventive benefits of obesity surgery extend to a broad range of patients and underscore the value of effective obesity treatment for long-term health.
This work was supported by the Swedish Cancer Society, the Nordic Cancer Union, Region Stockholm, and the Swedish Society of Medicine.
Publication
Bariatric surgery and risk of obesity-related cancer by age and sex in a multinational cohort. Radkiewicz C, Santoni G, Kauppila JH, et al. JAMA Surg. Published online October 14, 2026. doi:10.1001/jamasurg.2026.4798