Objective: The aim of this study was to determine oncological outcomes and incidence of lymph node (LN) metastases in women who underwent systematic pelvic and paraaortic lymphadenectomy for surgical staging of apparent stage I low-grade epithelial ovarian cancer (LGEOC). Materials and Methods: A retrospective study was performed at nine institutions across Europe and the US, and patients who underwent surgical staging for presumed stage I LGEOC between 2000 and 2016 were included. To ensure surgical quality, a minimum number of ≥10 pelvic and ≥10 paraaortic LNs was required. Patients with preoperative radiologic or clinical evidence of extraovarian or LN disease, and those with nonepithelial histology, were excluded. Results: The overall incidence of LN metastases was 4.3% in the 163 evaluated patients, and the incidence of LN involvement in serous, endometrioid, and mucinous subtypes was 10.7, 1.5, and 0%, respectively. However, Upstaging due to LN involvement alone occurred in only 2.4% of the patients. Eighty-nine (54.6%) patients received adjuvant chemotherapy due to International Federation of Gynecology and Obstetrics stage IC or higher disease. The 5-year progression-free survival (PFS) and overall survival (OS) were 93.2% (95% confidence interval [CI] 89.4–97.1%) and 94.5% (95% CI 90.9–98.0%), respectively. There was no significant difference in PFS or OS between LN-negative and LN-positive patients. However, fewer patients received adjuvant chemotherapy in the LN-negative group. Multivariate analysis did not identify any independent prognostic factor of survival. Conclusion: The risk of LN involvement in nonserous apparent stage I LGEOC appears low, with a rate of <1% in this retrospective analysis, raising questions about the value of lymphadenectomy in those patients. Larger-scale prospective studies are warranted to evaluate the oncologic safety of omitting systematic LN staging in apparent stage I nonserous LGEOC.
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