Bariatric Surgery is Associated With Reduced Risk of Breast Cancer in Both Premenopausal and Postmenopausal Women

Abstract

Objective: This retrospective cohort study examined whether bariatric surgery is associated with reduced risk of breast cancer among pre- and postmenopausal women. Background: Obesity is associated with increased risk of breast cancer, but the impact of weight loss on breast cancer risk has been difficult to quantify. Methods: The cohort included obese (body mass index ≥35 kg/m2) patients enrolled in an integrated health care delivery system between 2005 and 2012 (with follow-up through 2014). Female bariatric surgery patients (N = 17,998) were matched on body mass index, age, study site, and comorbidity index to 53,889 women with no bariatric surgery. Kaplan–Meier curves and Cox proportional hazards models were used to examine incident breast cancer up to 10 years after bariatric surgery. Pre- and postmenopausal women were examined separately, and further classified by estrogen receptor (ER) status. Results: The analysis included 301 premenopausal and 399 postmenopausal breast cancer cases. In multivariable adjusted models, bariatric surgery was associated with a reduced risk of both premenopausal (HR = 0.72, 95% CI, 0.54–0.94) and postmenopausal (HR = 0.55, 95% CI, 0.42–0.72) breast cancer. Among premenopausal women, the effect of bariatric surgery was more pronounced among ER-negative cases (HR = 0.36, 95% CI, 0.16–0.79). Among postmenopausal women, the effect was more pronounced in ER-positive cases (HR = 0.52, 95% CI, 0.39–0.70). Conclusions: Bariatric surgery was associated with a reduced risk of breast cancer among severely obese women. These findings have significant public health relevance because the prevalence of obesity continues to rise, and few modifiable breast cancer risk factors have been identified, especially for premenopausal women.

Microbiome, bile acids, and obesity: How microbially modified metabolites shape anti‐tumor immunity

“…123,132 Of note for subtype-specific BC, bariatric surgery led to a 64% reduced risk in premenopausal ER tumors like TNBC. 133 Importantly, it is not yet clear from this and other clinical studies if this benefit from surgery arises from weight loss per se or is a surgery-associated benefit.…”

Review: Sex-Specific Aspects in the Bariatric Treatment of Severely Obese Women

“…Among women, sex-specific cancer represents a large proportion of malignant diseases: breast cancer is the most common and cervical cancer is the sixth most common cancer entity globally [115]. Decreased estrogen levels have been supposed to increase the risk of developing breast and endometrial cancer and are therefore among the reasons for the increased incidence of malignant diseases in women [116]. Endometrial hyperplasia is a precancerous condition that arises in the presence of chronic exposure to estrogen unopposed by progesterone, such as in PCOS and obesity [42].…”

“…With regard to breast cancer, there is even less scientific evidence regarding the influence of bariatric surgery. A retrospective cohort study of BMI-and aged-matched women with and without bariatric surgery showed that the surgery was associated with reduced risk of both pre-and postmenopausal breast cancer [116].…”

New clarity on cancer risk reduction after bariatric surgery

“…A separate follow‐up study provided more clarity regarding the risk reduction for breast cancer in both postmenopausal and premenopausal women 3 . “We have good evidence that obesity is associated with postmenopausal breast cancer,” Dr. Feigelson says.…”