# Bariatric surgery and cancer incidence

Source: https://onco.cc/technologies/bariatric-surgery-cancer-incidence/  
OnCo record `bariatric-surgery-cancer-incidence` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

People with severe obesity who have weight-loss surgery develop about a third fewer cancers over the following decade, especially womb and other hormone-related cancers, than similar people who do not.

## Summary

The Swedish Obese Subjects study (prospective, matched controls, more than 20 years' follow-up) and several large cohorts (SPLENDID, Cleveland Clinic, JAMA 2022, n=30,318) show that bariatric surgery is associated with a roughly 30-35% reduction in obesity-associated cancer incidence and lower cancer mortality, with the largest effects in endometrial cancer and in women. This is the strongest evidence that deliberately reversing obesity reduces cancer, though it remains non-randomised: no trial has randomised surgery with cancer as the outcome and the populations that undergo surgery differ from those that do not. A small increase in colorectal cancer risk after some procedures has been reported in Scandinavian registries and is unexplained. Whether GLP-1 receptor agonists reproduce the effect at scale is the live question.

## Fields

- Kind: Technology
- Status: established
- Last checked: 2026-09-08
- Principle: Substantial, sustained weight loss lowers circulating insulin, oestrogens and inflammatory cytokines and reverses the metabolic and endometrial changes that drive obesity-related carcinogenesis.
- Since: 2007
- Strengths: Large, long-term cohorts with matched controls; Effect on endometrial cancer is large and biologically coherent; Demonstrates reversibility of obesity-related cancer risk
- Limitations: No randomised evidence; Possible increased colorectal risk after some procedures; Applies only to severe obesity

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Bariatric_surgery
- SPLENDID (JAMA 2022): https://doi.org/10.1001/jama.2022.9009
- SOS study cancer (Lancet Oncol 2009): https://doi.org/10.1016/S1470-2045(09)70159-7

## Connected records

- ideas: [Link bariatric and GLP-1 registries to cancer registries in every country that has both](https://onco.cc/ideas/idea-nl-bariatric-cancer-registry-linkage/)
- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/), [Endometrial cancer](https://onco.cc/cancers/endometrial/), [Hepatocellular carcinoma](https://onco.cc/cancers/hcc/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/), [Renal cell carcinoma](https://onco.cc/cancers/rcc/)
- fronts: [Diet, Exercise & Lifestyle](https://onco.cc/fronts/nutrition-lifestyle/), [Prevention & Risk](https://onco.cc/fronts/prevention/), [Surgery & Interventional](https://onco.cc/fronts/surgery/)
- technologies: [Chemoprevention & risk-reducing surgery](https://onco.cc/technologies/chemoprevention/), [GLP-1 receptor agonists and obesity-related cancer risk](https://onco.cc/technologies/glp1-agonists-cancer-risk/)
- institutions: [Cleveland Clinic Taussig Cancer Institute](https://onco.cc/institutions/cleveland-clinic/)
- terms: [Metabolic syndrome and insulin resistance](https://onco.cc/terms/metabolic-syndrome/), [Obesity-related cancers (IARC list of 13)](https://onco.cc/terms/obesity-related-cancers/)
- bottlenecks: [Prevention we already have is not deployed](https://onco.cc/bottlenecks/b-prevention-adoption/), [Weak real-world evidence and registries](https://onco.cc/bottlenecks/b-real-world-evidence/)
- key papers: [Association of Bariatric Surgery With Cancer Risk and Mortality in Adults With Obesity](https://onco.cc/key-papers/paper-aminian-jama/), [Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial](https://onco.cc/key-papers/paper-sjostrom-lancet-oncol/)
- pathways: [Lipid synthesis, uptake & cholesterol](https://onco.cc/pathways/lipid-metabolism-cancer/)
- roadmaps: [Cancer prevention roadmap: tobacco control and vaccines → biomarker-guided chemoprevention → interception in carriers](https://onco.cc/roadmaps/prevention-roadmap/), [Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment](https://onco.cc/roadmaps/nutrition-lifestyle-roadmap/)

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