Bariatric surgery and cancer incidence
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.
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.
How it works
Substantial, sustained weight loss lowers circulating insulin, oestrogens and inflammatory cytokines and reverses the metabolic and endometrial changes that drive obesity-related carcinogenesis.
- Large, long-term cohorts with matched controls
- Effect on endometrial cancer is large and biologically coherent
- Demonstrates reversibility of obesity-related cancer risk
- No randomised evidence
- Possible increased colorectal risk after some procedures
- Applies only to severe obesity
Latest papers
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