OBJECTIVE: To investigate survival outcomes in endometrioid endometrial cancer (EEC) patients with single vs. multiple positive pelvic lymph nodes.METHODS: We performed a retrospective evaluation of all consecutive patients with histologically proven International Federation of Gynecology and Obstetrics (FIGO) stage IIIC1 EEC who underwent primary surgical treatment between 2004 and 2014 at seven Italian gynecologic oncology referral centers. Patients with pre- or intra-operative evidence of extra-uterine disease (including the presence of bulky nodes) and patients with stage IIIC2 disease were excluded, in order to obtain a homogeneous population.RESULTS: Overall 140 patients met the inclusion criteria. The presence of >1 metastatic pelvic node was significantly associated with an increased risk of recurrence and mortality, compared to only 1 metastatic node, at both univariate (recurrence: hazard ratio [HR]=2.19; 95% confidence interval [CI]=1.2-3.99; p=0.01; mortality: HR=2.8; 95% CI=1.24-6.29; p=0.01) and multivariable analysis (recurrence: HR=1.91; 95% CI=1.02-3.56; p=0.04; mortality: HR=2.62; 95% CI=1.13-6.05; p=0.02) and it was the only independent predictor of prognosis in this subset of patients. Disease-free survival (DFS) and disease-specific survival (DSS) were significantly longer in patients with only 1 metastatic node compared to those with more than 1 metastatic node (p=0.008 and 0.009, respectively).CONCLUSION: The presence of multiple metastatic nodes in stage IIIC1 EEC represents an independent predictor of worse survival, compared to only one positive node. Our data suggest that EEC patients may be categorized according to the number of positive nodes. Copyright © 2018. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology.