Objectives To assess risk factors for lymph node involvement in patients with endometrial cancer and a body-mass index (BMI) ≥30 kg/m².

Methods A retrospective analysis was performed of obese patients diagnosed with endometrial carcinoma between 2007 and 2015, treated in a single center in Montreal. Preoperative variables evaluated were age, BMI, parity, and preoperative ASA score, grade, CA-125 and histology. Odds ratios (OR) and hazard ratios (HR) and their respective 95% confidence intervals (95%CI) were calculated using multivariable logistic regression and Cox proportional hazard models.

Results The study included 230 women with BMI >30, 223 (97.0%) had complete staging. Pelvic lymph node involvement was detected in 26 patients (11.3%). Sentinel node detection and pelvic lymph node dissection decreased with increasing BMI (adjusted OR 0.86, 95% CI 0.76–0.97 and 0.76, 95%CI 0.59–0.96, respectively, per 1 kg/m² increment). Pelvic lymph node involvement was inversely correlated with BMI (adjusted OR 0.88, 95% CI 0.79–0.99) and present in 16/85 (18.8%), 6/56 (10.7%), and 4/82 (4.9%) of patients with a BMI of 30.0–34.9, 35.0–39.9, and ≥40.0 kg/m², respectively. Preoperative CA-125 was associated with lymph node involvement (adjusted OR 2.77, 95%CI 1.62–4.73, per quartile increment). During a median follow-up of 72 months, a higher BMI was not associated with worse recurrence-free survival (adjusted HR 1.04, 95%CI 0.98–1.10), disease-specific survival (adjusted HR 0.97, 95%CI 0.88–1.06), or overall survival (adjusted HR 0.92, 95% CI 0.84–0.99).

Conclusions Pelvic lymph node dissection might be omitted in selected cases of morbidly obese patients with failed sentinel nodes mapping and a low CA-125.