Objectives To assess the effect of complete surgical staging and adjuvant chemotherapy on survival in stage I, low grade endometrioid ovarian cancer.

Methods This retrospective study was conducted at two cancer centers from July 2001 to December 2019. Inclusion criteria were all stage I, grade 1 and 2 endometrioid ovarian cancer patients. Patients with mixed histology, concurrent endometrial cancer, neoadjuvant chemotherapy, and patients who did not undergo follow-up at our centers were excluded. Clinical, pathologic, recurrence, and follow-up data were collected. Cox proportional hazard model evaluated predictive factors. Recurrence-free survival and overall survival were calculated using the Kaplan-Meier method.

Results There were 131 eligible stage I patients: 83 patients (63.4%) were stage IA, 5 (3.8%) were stage IB, and 43 (32.8%) were stage IC, with 80 patients (61.1%) having grade 1 and 51 (38.9%) patients having grade 2 disease. Complete lymphadenectomy was performed in 34 patients (26.0%), whereas 97 patients (74.0%) had either partial (n=22, 16.8%) or no (n=75, 57.2%) lymphadenectomy. Thirty patients (22.9%) received adjuvant chemotherapy. Median follow-up was 51.5 (95% CI 44.3 to 57.2) months. Five-year recurrence-free survival was 88.0% (95% CI 81.6% to 94.9%) and 5 year overall survival was 95.1% (95% CI 90.5% to 99.9%). In a multivariable analysis, only grade 2 histology had a significantly higher recurrence rate (HR 3.42, 95% CI 1.03 to 11.38; p=0.04). There was no difference in recurrence-free survival (p=0.57) and overall survival (p=0.30) in patients with complete lymphadenectomy. In stage IA/IB, grade 2 there was no benefit of adjuvant chemotherapy (p=0.19), and in stage IA/IB, low grade without complete surgical staging there was no benefit of adjuvant chemotherapy (p=0.16). Twelve patients (9.2%) had recurrence; 3 (25%) were salvageable at recurrence and are alive with no disease.

Conclusions Patients with stage I, low grade endometrioid ovarian cancer have a favorable prognosis, and adjuvant chemotherapy and staging lymphadenectomy did not improve survival.