New research published in JAMA Surgery found that bariatric surgery was associated with a lower incidence of obesity-related cancers, with similar findings across age groups and sexes.
Bariatric surgery is well established as a treatment for obesity, helping eligible patients achieve significant weight loss and improve obesity-related health conditions. But its potential long-term health benefits extend beyond the number on the scale.
A new study published in JAMA Surgery on October 14, 2026, adds to the growing body of evidence examining the relationship between bariatric surgery and cancer risk. Researchers found that people with obesity who underwent bariatric surgery had a lower overall incidence of obesity-related cancers than those who did not undergo surgery.
The study included more than 784,000 individuals in Denmark, Finland, and Sweden, making it a substantial investigation into the long-term relationship between obesity treatment and cancer.
Bariatric Surgery Was Associated With 19% Lower Cancer Incidence
The study, titled Bariatric Surgery and Risk of Obesity-Related Cancer by Age and Sex, analyzed registry data from 784,105 individuals with obesity between 1992 and 2023. Of these, 99,614 underwent bariatric surgery.
After adjusting for several demographic, medical, and lifestyle-related factors, researchers found that bariatric surgery was associated with a 19% lower incidence of obesity-related cancers compared with no surgery.
The adjusted incidence rate ratio (aIRR) was 0.81, with a 95% confidence interval of 0.77 to 0.85.
In practical terms, the observed incidence of the cancers studied was lower among people who underwent bariatric surgery. This finding is important because obesity is associated with an increased risk of several cancers, and effective obesity treatment may have implications for long-term health beyond weight management.
However, the study was observational. Its findings demonstrate an association, not proof that bariatric surgery directly prevents cancer. The 19% figure also represents a relative difference in incidence rates, not an individual’s absolute reduction in cancer risk.
Which Cancers Showed the Strongest Associations?
Researchers evaluated several obesity-related cancers, including cancers of the liver, endometrium, ovaries, breast, esophagus, pancreas, colon, rectum, and kidneys, as well as multiple myeloma.
The strongest inverse associations were observed for liver, endometrial, and ovarian cancer.
| Cancer outcome | Adjusted incidence rate ratio (aIRR) | Relative association |
| Liver cancer | 0.49 (95% CI, 0.34–0.70) | Approximately 51% lower incidence |
| Endometrial cancer | 0.51 (95% CI, 0.45–0.59) | Approximately 49% lower incidence |
| Ovarian cancer | 0.73 (95% CI, 0.60–0.87) | Approximately 27% lower incidence |
| All obesity-related cancers combined | 0.81 (95% CI, 0.77–0.85) | Approximately 19% lower incidence |
| Multiple myeloma | 1.09 (95% CI, 0.82–1.47) | No statistically significant association |
Source: Radkiewicz et al., JAMA Surgery, 2026. Percentages are calculated from the reported adjusted incidence rate ratios. They represent relative associations, not absolute risk reductions for individual patients.
Liver cancer: One of the strongest findings
The association was particularly notable for liver cancer. An adjusted incidence rate ratio of 0.49 indicates that the observed incidence was approximately 51% lower in the bariatric surgery group than in the group that did not undergo surgery.
Endometrial cancer: A substantial inverse association
Endometrial cancer develops in the lining of the uterus. The study found an adjusted incidence rate ratio of 0.51, corresponding to approximately 49% lower incidence associated with bariatric surgery.
Ovarian cancer: Another encouraging result
For ovarian cancer, the adjusted incidence rate ratio was 0.73, corresponding to approximately 27% lower incidence in the surgery group.
Together, these findings highlight an important area of ongoing research into how treating obesity may influence the development of certain cancers over time.
What about multiple myeloma?
The findings were not statistically significant for every cancer examined. For multiple myeloma, the adjusted incidence rate ratio was 1.09, with a 95% confidence interval of 0.82 to 1.47.
Because this interval includes 1.0, the study did not establish a statistically significant association between bariatric surgery and multiple myeloma incidence. The results do not demonstrate a protective effect or establish that surgery increases the risk of this cancer.
Similar Findings Across Age Groups and Sexes
Another important finding was that the association between bariatric surgery and lower overall obesity-related cancer incidence was similar in the two age groups studied.
- Adults aged 18–39: aIRR of 0.80, corresponding to approximately 20% lower incidence.
- Adults aged 40–59: aIRR of 0.81, corresponding to approximately 19% lower incidence.
Researchers found no statistically meaningful difference in the association between these age groups.
The study also found similar associations for cancers not specific to one sex among women and men.
These results suggest that the observed association was not limited to younger adults, adults aged 40–59, or one sex. However, the study included individuals aged 18 to 59, so its results should not automatically be extended to older age groups.
An Important Finding: Pancreatic Cancer Requires Further Research
A balanced discussion of this study must also address its pancreatic cancer results.
Researchers observed an increased incidence of pancreatic cancer in the bariatric surgery group, particularly among adults aged 18–39. In this younger age group, the adjusted incidence rate ratio was 2.21 (95% CI, 1.44–3.39).
This means the observed incidence rate was more than twice that of the comparison group in this age category.
This finding deserves further investigation, but it does not prove that bariatric surgery causes pancreatic cancer. Because the study was observational, the results cannot establish the reason for this association. Additional research is needed to understand the finding and its implications.
This is an important reminder that medical research can identify promising associations while also raising questions that require further study. Patients should discuss the potential benefits and risks of bariatric surgery with a qualified medical professional and continue appropriate long-term medical follow-up.
Why These Findings Matter for Obesity Treatment
Obesity is a complex, chronic disease associated with numerous health risks. Its treatment should be evaluated not only in terms of weight loss, but also in the context of long-term health, obesity-related conditions, and quality of life.
The findings published in JAMA Surgery add to the evidence suggesting that bariatric surgery may be associated with benefits beyond weight reduction. The lower overall incidence of obesity-related cancers and the similar associations across the age groups and sexes examined are important considerations in conversations about obesity treatment.
At the same time, bariatric surgery is not a guarantee against cancer. It does not eliminate cancer risk or replace recommended cancer screening, preventive care, or routine medical evaluations.
The decision to undergo surgery should be based on an individualized medical assessment that considers a patient’s health history, existing conditions, treatment goals, and the potential benefits and risks of the procedure.
Looking Beyond the Number on the Scale
At Do It Bariatrics, we believe conversations about bariatric surgery should focus on the whole patient and the potential long-term implications of treating obesity.
Research like this helps expand the conversation beyond weight loss alone. It reinforces the importance of understanding obesity as a medical condition and evaluating treatment options in the context of overall health.
Dr. Louisiana Valenzuela, MD, FACS, and the Do It Bariatrics team help patients explore bariatric surgery options and understand the process involved in making an informed treatment decision.
If you are considering bariatric surgery, learning about the current evidence, potential benefits, and limitations can help you have a more informed conversation with your healthcare team.
From Do It to Did It. 💙
Contact Do It Bariatrics to learn more about bariatric surgery with Dr. Louisiana Valenzuela and find out whether a surgical approach may be appropriate for your individual circumstances.
Research Reference
Radkiewicz, C., Santoni, G., Kauppila, J. H., Ness-Jensen, E., von Euler-Chelpin, M., Holmberg, D., & Lagergren, J. (2026). Bariatric Surgery and Risk of Obesity-Related Cancer by Age and Sex. JAMA Surgery. Advance online publication, October 14, 2026. https://doi.org/10.1001/jamasurg.2026.4798
