Lymph node staging in grade 1-2 endometrioid ovarian carcinoma apparently confined to the ovary: Is it worth?

Objective: The aim of this study was to assess the disease-free survival (DFS) and overall survival (OS) of patients with grade 1-2 endometrioid ovarian carcinoma apparently confined to the ovary, according to surgical staging. Methods: Multicenter, retrospective, observational cohort study. Patients with endometrioid ovarian carcinoma, surgical procedure performed between May 1985 and December 2019, stage pT1 N0/N1/Nx, grade 1-2 were included. Patients were stratified according to lymphadenectomy (defined as removal of any lymph node versus no lymph node assessment), and subgroup analyses according to tumor grade were performed. Kaplan-Meier curves and cox regression analyses were used to perform survival analyses. Results: 298 patients were included. 199 (66.8 %) patients underwent lymph node assessment. Of these, 166 (83.4 %) had unilateral/bilateral pelvic and para-aortic/caval lymphadenectomy. Eleven (5.5 %) patients of those who underwent lymph node assessment showed pathologic metastatic lymph nodes (FIGO stage IIIA1). Twenty-seven patients (9.1 %) had synchronous endometrioid endometrial cancer. After a median follow up of 45 months (95 %CI:37.5-52.5), 5-year DFS and OS of the entire cohort were 89.8 % and 96.2 %, respectively. Age <= 51 years (HR=0.24, 95 %CI:0.06-0.91; p = 0.036) and performance of lymphadenectomy (HR=0.25, 95 %CI: 0.07-0.82; p = 0.022) represented independent protective factors toward risk of death. Patients undergoing lymphadenectomy had better 5-year DFS and OS compared to those not receiving lymphadenectomy, 92.0 % versus 85.6 % (p = 0.016) and 97.7 % versus 92.8 % (p = 0.013), respectively. This result was confirmed after exclusion of node-positive patients. When stratifying according to tumor grade (node-positive excluded), patients with grade 2 who underwent lymphadenectomy had better 5-year DFS and OS than those without lymphadenectomy (93.0 % versus 83.1 %, p = 0.040 % and 96.5 % versus 90.6 %, p = 0.037, respectively). Conclusion: Staging lymphadenectomy in grade 2 endometrioid ovarian carcinoma patients was associated with improved DFS and OS. Grade 1 and grade 2 might be considered as two different entities, which could benefit from different approach in terms of surgical staging. Prospective studies, including molecular profiles are needed to confirm the survival drivers in this rare setting.