Introduction/Background The prevalence of obesity in the United States has tripled over the last 40 years. Obesity is a significant risk factor for endometrial cancer (EC). Sentinel lymph node (SLN) sampling has been applied for EC surgery to minimize the rate of unnecessary LND associated morbidity. Although its use in EC is relatively new, SLN biopsy has been shown to be highly accurate for staging purpose. However, some studies reported on decreased sentinel node detection rate among obese patients. Thus, we sought to determine if SLN technique is reliable with certain factors associated with successful mapping in obese EC patients and whether omitting LND impacts oncologic outcomes.

Methodology A prospective cohort study of obese patients (BMI) ≥35 kg/m2), diagnosed with endometrial carcinoma between 2007 and 2017, comparing surgical and oncological outcomes of two patients cohorts: LND (± SLN) and SLN. 2-year progression-free survival (PFS), overall survival (OS), and disease-specific survival (DSS) were analyzed using life tables, Kaplan-Meier survival curves and log-rank tests.

Results Out of 223 patients with median BMI of 40.6 kg/m2, 140 patients underwent LND (with or without SLN) and 83 patients underwent SLN. The median operative time for surgical staging in SLN only group was shorter in 47.5 minutes than for patients in the LND±SLN group (190.5 minutes (108–393) vs. 238 minutes (131–440), respectively, (p < 0.001)), and they had reduced estimated blood loss (EBL) compared to the LND±SLN group (30 ml (0–300) vs. 40 ml (0–800 ml), P=0.03). At a 24 months follow-up cut-off, 98% of the patients were alive and 95.5% were free of disease, without significant differences in OS, DSS and PFS between the two groups (p=0.7, p=0.8 and p=0.4, respectively). Overall, 171 patients underwent SLN biopsy (±LND) and stratified by the tracer used for mapping (ICG versus blue dye). The ICG injected group had higher successful mapping and bilateral detection rates (92.8% vs 71.7%, p<0.001 and 80.2% vs 43.3%, p<0.001, respectfully).

Conclusion Omitting LND from surgical staging where SLN is performed was associated with shorter operative time and minimal bleeding without affecting survival. ICG with NIR fluorescence imaging results in higher detection than with blue dye, indicating that ICG should be the dye of choice in obese endometrial cancer patients.

Disclosures We have no disclosures.