The effect of bariatric surgery on breast cancer incidence and characteristics: A meta-analysis and systematic review

BACKGROUND: Obesity is a major risk factor for breast cancer. This study examines whether bariatric surgery affects breast cancer incidence in women with obesity compared to BMI-matched controls. METHODS: EMBASE, MEDLINE, Web of Science, and CINAHL were searched. Primary studies on female breast cancer incidence after bariatric surgery were eligible. RESULTS: 11 studies were included (n = 1,106,939). The rate of cancer diagnosis was lower in the surgical group (0.54%) compared to control (0.84%; risk ratio (RR) 0.50, 95%CI 0.37-0.67, I² = 88%). The results were robust to sensitivity analyses for patient age and study size. Bariatric surgery was associated with increased risk of stage I cancer (RR 1.23, 95%CI 1.06-1.44) and reduced risk of stage III or IV cancer (RR 0.50, 95%CI 0.28-0.88). Hormone receptor characteristics were not affected. CONCLUSIONS: Bariatric surgery is associated with reduced incidence and earlier stage at diagnosis of breast cancer in women with obesity compared to BMI-matched controls.