Obesity Surgery Linked to Lower Cancer Risk Across Ages and Sexes

Large Nordic study links bariatric surgery with lower cancer risk

Bariatric surgery was associated with an approximately 20% lower risk of obesity-related cancer in a large Nordic registry study led by researchers at Karolinska Institutet. The association was similar across age groups and, for cancers affecting both women and men, did not differ by sex.

The findings, published in JAMA Surgery, add long-term evidence to the understanding of bariatric surgery’s health effects. They also address questions that have remained unsettled in earlier research, including whether the apparent cancer-risk reduction is stronger for women and whether age at the time of surgery changes the result.

Registry data across three countries

The researchers studied more than 780,000 people with obesity in Sweden, Denmark and Finland. Nearly 100,000 of those people had undergone obesity surgery.

They compared subsequent diagnoses of cancers linked to obesity between people who received surgery and people with obesity who did not. The study focused on obesity-related cancers, a group that includes several gastrointestinal cancers as well as cancers such as liver, endometrial and ovarian cancer.

Several cancers associated with obesity, particularly gastrointestinal cancers, have been increasing in Western populations. Previous work had suggested that surgery could reduce the risk of these cancers, but the size and consistency of the association for particular cancers had varied among studies.

Benefits were not limited to one demographic group

The new analysis found no evidence that the association between surgery and lower cancer risk changed according to whether people had surgery at younger or older ages. It also found no difference by sex for cancers that occur in both women and men.

That result is important because earlier findings had sometimes appeared to show a larger protective association among women. The Nordic data instead suggest that the long-term association is broadly present across the groups examined, rather than being confined to a narrow patient population.

“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,” Cecilia Radkiewicz, a researcher at Karolinska Institutet and the study’s first author, said in a release.

Largest reductions seen for selected cancers

The largest risk reductions in the study were observed for liver, endometrial and ovarian cancers. The supplied study summary does not establish that surgery eliminates cancer risk, nor does it identify a single biological mechanism responsible for the association. Rather, it reports a lower observed risk among people with obesity who underwent surgery compared with those who did not.

That distinction matters when interpreting results from registry-based research. The work can examine outcomes at a scale that would be difficult to achieve in a conventional clinical trial, but it reports an association observed in real-world populations. It should not be read as a guarantee of an individual outcome or as a substitute for medical advice tailored to a patient’s circumstances.

What the results add

The study strengthens evidence that bariatric surgery’s effects may extend beyond weight loss and the immediate treatment of obesity-related conditions. By finding a similar association across age groups and sexes, it provides clinicians and researchers with a broader picture of the population in which the cancer-risk finding was observed.

It also points to areas for continued investigation. Researchers will need to clarify why some cancer types showed particularly large reductions, how long the association persists, and how it relates to other changes following surgery. Those questions are especially relevant as obesity-related cancers continue to pose a growing public-health concern in Western countries.

For now, the main finding is straightforward: in this large cohort spanning three Nordic countries, people with obesity who underwent bariatric surgery had a lower risk of developing obesity-related cancer, and that association was not materially altered by age at surgery or sex.

This article is based on reporting by Medical Xpress. Read the original article.