Sex differences in the association between the effect of bariatric surgery and cancer risk: A meta-analysis including 18 million individuals

Abstract

Abstract Background Studies have suggested an association between bariatric surgery for obesity with cancer risk. Whether the effect of bariatric surgery could reduce the same excess risk of overall cancer in women and men is unknown. Methods PubMed, EMBASE, and Web of Science were searched to identify cohort studies up to 15 September 2022. Included studies reported the association between bariatric surgery for obesity and cancer risk in men and/or female. Random-effects meta-analyses weighted by the inverse of the variances were applied to pool sex-specific RRs and women-to-men ratios of RRs (RRRs) for overall cancer risk. Results 18 studies involved with 18,603,812 patients (18,028,898 controls and 573,914 bariatric patients) met the inclusion criteria and were eligible for analysis. The results showed that bariatric surgery was significantly associated with decreased overall cancer risk (RR = 0.68, 95% CI 0.60, 0.78; P < 0.001) in women, but not associated with overall cancer risk (RR = 0.94, 95% CI 0.79, 1.12; P = 0.470) in men. The pooled women-to-men RRR showed an 18% lower reduction of overall cancer associated with bariatric surgery in women than in men (RRR = 0.82, 95% CI 0.75–0.90; P < 0.001). The pooled women-to-men RRR showed an 18% lower reduction of overall cancer associated with bariatric surgery in women than in men RRR = 0.82, 95% CI 0.74–0.92; P < 0.001). Conclusion The effect of bariatric surgery is significantly associated with a lower reduction of cancer for women compared to men.