Long‐term cancer outcomes after bariatric surgery

Abstract

ObjectiveObesity is associated with increased cancer risk. Because of the substantial and sustained weight loss following bariatric surgery, postsurgical patients are ideal to study the association of weight loss and cancer.MethodsRetrospectively (1982–2019), 21,837 bariatric surgery patients (surgery, 1982–2018) were matched 1:1 by age, sex, and BMI with a nonsurgical comparison group. Procedures included gastric bypass, gastric banding, sleeve gastrectomy, and duodenal switch. Primary outcomes included cancer incidence and mortality, stratified by obesity‐ and non‐obesity‐related cancers, sex, cancer stage, and procedure.ResultsBariatric surgery patients had a 25% lower risk of developing any cancers compared with a nonsurgical comparison group (hazard ratio [HR] 0.75; 95% CI 0.69–0.81; p < 0.001). Cancer incidence was lower among female (HR 0.67; 95% CI 0.62–0.74; p < 0.001) but not male surgery patients, with the HR lower for females than for males (p < 0.001). Female surgery patients had a 41% lower risk for obesity‐related cancers (i.e., breast, ovarian, uterine, and colon) compared with nonsurgical females (HR 0.59; 95% CI 0.52–0.66; p < 0.001). Cancer mortality was significantly lower after surgery in females (HR 0.53; 95% CI 0.44–0.64; p < 0.001).ConclusionsBariatric surgery was associated with lower all‐cancer and obesity‐related cancer incidence among female patients. Cancer mortality was significantly lower among females in the surgical group versus the nonsurgical group.

Breast Cancer Risk After Bariatric Surgery and Influence of Insulin Levels

“…43 However, recent retrospective reports on bariatric surgery in women with obesity showed a reduced risk of both premenopausal and postmenopausal breast cancer, compared to women not undergoing surgery. 16,17 To summarize, there are several different pathways by which bariatric surgery may reduce breast cancer risk in women with obesity, highlighting the need for further studies. We speculate that our findings are explained by both the decreased insulin levels after bariatric surgery 44 as well as reduced estrogen levels due to weight loss.…”

“…In women who are premenopausal, the data are more unclear with some studies showing lower levels of estrogen and a reduced risk of breast cancer in those with obesity . However, recent retrospective reports on bariatric surgery in women with obesity showed a reduced risk of both premenopausal and postmenopausal breast cancer, compared to women not undergoing surgery …”

“…We have also shown that bariatric surgery is associated with a reduced risk of female-specific cancer in women with obesity, especially in those with high insulin levels at baseline . Retrospective observational studies indicate that bariatric surgery may reduce breast cancer incidence in both women with obesity who were premenopausal and those who were postmenopausal, but this remains to be verified . Furthermore, the biological mechanisms underlying the observed reduction of cancer risk in people undergoing bariatric surgery are currently not well understood and require further investigation .…”

“…15 Retrospective observational studies indicate that bariatric surgery may reduce breast cancer incidence in both women with obesity who were premenopausal and those who were postmenopausal, but this remains to be verified. 16,17 Furthermore, the biological mechanisms underlying the observed reduction of cancer risk in people undergoing bariatric surgery are currently not well understood and require further investigation. 18 To this end, large prospective studies with detailed patient information and data from national registries are needed.…”