Impact of Obesity on Sentinel Lymph Node Mapping in Patients with apparent Early-Stage Endometrial Cancer: The ObeLyX study

Conflicting data exists on the impact of Body Mass Index (BMI) on sentinel lymph-node (SLN) detection. The primary study endpoint was to investigate the impact of obesity on overall detection rate, bilateral mapping, and mapping failure rate of SLN. In addition, we evaluated possible differences in terms of surgical management and "empty-packet dissection" rate among obese and non-obese patients.Multicenter, propensity-matched, retrospective study. Patients with apparent early-stage endometrial cancer were included. Study population was divided into women with BMI/≥ 30 (Group-1 and Group-2). To lower the selection bias, a propensity-matched analysis was performed. Matching was based on histotype (endometrioid vs non-endometrioid), age (/≥65 years old), and presence of lymph-vascular space invasion.Eight-hundred forty-four women were enrolled. After a 1:1 propensity-matched analysis, 764 patients were identified (Group-1 n = 382, Group-2 n = 382). A 1.156-fold increase in the risk of mapping failure for every 5 units of BMI increase was found (OR 1.156, 95% CI 1.033-1.294, p = 0.012), with a consequently decrease in bilateral mapping and overall detection rate (respectively OR 0.865, 95% CI 0.773-0.968, p = 0.012 and OR 0.785, 95% CI 0.670-0.920, p = 0.003). Obese patients were surgically under-staged in 9.4% of cases and showed an 8.2% of empty packet dissection (surgical under-staging: 5.0% vs 9.4%, p = 0.017; empty-packet dissection: 3.9% vs 8.2%, p = 0.022).BMI was confirmed as a statistically relevant predictor of mapping failure and decreased overall detection rate. In addition, obese women had a significantly higher odds of empty packet dissection.