Cancer incidence following bariatric surgery in renal transplant recipients: a retrospective multi-center analysis

Background: Obesity, a known independent risk factor for developing malignancy. Additionally, renal transplant recipients (RTR) confer a 2- to 4-fold increased risk of overall malignancies with an excess absolute risk of .7% per year. While transplant recipients are at risk for obesity and malignancy, the effect of bariatric surgery (BS) in the posttransplantation setting is not well known. Objectives: Our study primarily evaluated the impact of BS on cancer incidence in RTR with severe obesity in the posttransplantation setting. Weight loss outcomes were analyzed secondarily. Setting: University Hospital. Methods: A retrospective study using TriNetX database was developed to analyze cancer outcomes in RTR with posttransplantation BS versus RTR without BS from 2000 to 2023. After the exclusion process and propensity matching, both cohorts consisted of 153 patients. Results: RTR-BS had a significantly lower incidence of overall cancer and transplant-related cancers (P < .05). No significant difference was identified in cutaneous, gastrointestinal, and reproductive cancers. Percent Excess Weight Loss (%EWL) was significantly lower in RTR-only cohort (11.4%) versus RTR-BS cohort (57.8%) at 5 years. Sleeve gastrectomy (SG) patients (73.19%) had significantly higher %EWL than Roux en-Y gastric bypass (RYGB) patients (49.33%) at 3 years. No difference in cancer incidence was noted between SG and RYGB patients. Conclusion: Postrenal transplantation BS had a diminishing effect on overall and transplant-related cancer incidence in RTR with severe obesity. Significant weight loss was also demonstrated with post-renal transplantation BS.