Background: Recent studies have suggested that metabolic surgery reduces cancer risk. This study aims to determine if incident cancer is associated with the extent of weight loss after Roux-en-Y gastric bypass (RYGB).
Methods: Patients at a large tertiary bariatric surgery center were retrospectively reviewed to identify patients with no history of cancer at the time of RYGB. Diagnoses in the electronic health record, a tumor registry, and chart review were used to identify postoperative incident solid organ cancer. The overall incidence of organ cancer was estimated using Kaplan-Meier analysis. The percent total body weight loss (%TWL) in the 48 months after surgery but prior to cancer was compared between those that developed organ cancer versus those that did not using repeated measures linear regression.
Results: The 2943 patients had a mean age of 45.6 years (SD = 11.1), 81 % were female, and a mean baseline body mass index (BMI) of 47.2 kg/m2 (SD = 7.9). Median follow-up after surgery was 3.8 years (range = [<1, 12]). Incident organ cancer developed and was verified in 54 of the 2943 patients (1.8 %). Kaplan-Meier estimates for cancer at 3, 5, and 10 years postsurgery were 1.3, 2.5, and 4.2 %. After adjusting for age, BMI, sex, diabetes, hypertension, and dyslipidemia, patients that developed organ cancer achieved less weight loss (-1.5 % TWL, 95 % CI = [-2.9 %, -0.1 %], p = 0.034).
Conclusions: Greater weight loss after metabolic surgery may be associated with lower organ cancer risk.
Keywords: Cancer incidence; Cancer risk; Metabolic surgery; Obesity.