Association Between Metabolic and Bariatric Surgery and Melanoma Risk: A Systematic Review and Meta-analysis of Observational Studies.

In 30 seconds

This systematic review and meta-analysis of observational studies assessed whether metabolic and bariatric surgery (MBS) was associated with melanoma incidence compared with no MBS. Ten studies included 2,310,128 patients, of whom 445,947 underwent surgery. Melanoma incidence was 0.11% after MBS and 0.24% in controls. The pooled analysis found a slightly lower risk with MBS, but the difference was not statistically significant (risk ratio 0.78; 95% CI 0.52 to 1.16; p = 0.222), with substantial heterogeneity (I² = 85%).

Key findings

• Melanoma incidence was 0.11% in the MBS group (516 / 445,947) and 0.24% in controls (4,498 / 1,864,181).
• The pooled risk ratio was 0.78 (95% CI 0.52 to 1.16; p = 0.222), not a statistically significant difference.
• Between-study heterogeneity was substantial (I² = 85%).

Why it matters

Melanoma risk is an important potential outcome when evaluating the broader health associations of bariatric surgery. This synthesis does not establish that MBS reduces melanoma incidence: the pooled estimate is imprecise, the outcome was uncommon, and results varied substantially across studies. The findings help clarify current evidence while underscoring that the association remains uncertain.

What to keep in mind

The evidence came from observational studies and was rated very low certainty; melanoma was uncommon and heterogeneity was substantial (I² = 85%).