Citation: Pi ˛ atek, S.; Szymusik, I.; Sobiczewski, P.; Michalski, W.; Kowalska, M.; Oltarzewski, M.; Bidzi ´ nski, M. Obstetric Results after Fertility-Sparing Management of Non-Epithelial Ovarian Cancer. Cancers 2023, 15, 4170. https:// doi.org/10.3390/cancers15164170 Academic Editors: Bo R. Rueda, Giacomo Corrado, Ida Paris and Inge T. A. Peters Received: 1 August 2023 Accepted: 16 August 2023 Published: 18 August 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). cancers Article Obstetric Results after Fertility-Sparing Management of Non-Epithelial Ovarian Cancer Szymon Pi ˛ atek 1,2, * , Iwona Szymusik 3 , Piotr Sobiczewski 1 , Wojciech Michalski 1 , Magdalena Kowalska 1 , Mariusz Oltarzewski 4 and Mariusz Bidzi ´ nski 1,2 1 Department of Gynecologic Oncology, The Maria Sklodowska-Curie National Research Institute of Oncology, 02-781 Warsaw, Poland; sobiczewskipiotr7@gmail.com (P.S.); wojciech.michalski@pib-nio.pl (W.M.); magdapetryka@o2.pl (M.K.); bidzinski.m@gmail.com (M.B.) 2 Faculty of Medical Sciences and Health Sciences, Kazimierz Pulaski University of Technology and Humanities in Radom, 26-610 Radom, Poland 3 Department of Obstetrics, Perinatology and Neonatology, Center of Postgraduate Medical Education, 80 Ceglowska Street, 00-001 Warsaw, Poland; iwona.szymusik@gmail.com 4 Institute of Mother and Child, 01-211 Warsaw, Poland; mariusz.oltarzewski@imid.med.pl * Correspondence: szymon.piatek@aol.com Simple Summary: Fertility-sparing treatment (FST) is the gold standard for the majority of young women with non-epithelial ovarian cancer (NEOC). Its rarity and wide histological diversity lead to difficulties in assessing the oncological and reproductive outcomes. The aim of the study was to assess the recurrence rates and obstetric results of patients with NEOC. In a group of 146 patients, there was no difference in disease-free survival between the women with sex cord-stromal tumors (SCST) and germ cell tumors (GCT). The recurrence risk in the first two years after treatment exceeded the chance of childbearing. The cumulative incidence rate of childbearing rose continuously since the diagnosis. Chemotherapy was not related to the chance of having a child. FST can be offered to young women with NEOC regardless of their histology (SCST vs. GCT); however, pregnancy should be delayed until 2 years after receiving the treatment due to the increased risk of recurrence. Abstract: Purpose: To assess the recurrence and birth rates among patients with non-epithelial ovarian cancer. Methods: The study included 146 patients with germ cell (GCT, n = 84) and sex cord- stromal tumors (SCST, n = 62), who underwent fertility-sparing surgery. Adjuvant chemotherapy was administered to 86 (58.9%) patients. Most cases (133 out of 146) were staged FIGO I. Results: The 5- and 10-year disease-free survival rates were 91% and 83%, respectively. The recurrence risk was not associated with tumor histology, stage or age. Twenty-four months after the treatment, the rate of recurrence was higher than the rate of childbearing. The childbearing rates kept rising after the treatment and exceeded the rate of recurrence after 2 years. The cumulative incidence rates of birth 36, 60 and 120 months after treatment were 13.24%, 20.75%, and 42.37%, respectively. Chemotherapy was not related to childbearing. The patients’ age was related to the chance of childbearing. Conclusions: The prognoses of GCT and SCST are similar. Close follow-ups along with contraception should be offered to women during the first two years after treatment due to the increased risk of recurrence. After this period, relapses are rare and women can safely become pregnant. Keywords: non-epithelial ovarian cancer; germ cell tumor; sex cord-stromal tumor; fertility-sparing surgery; obstetric outcome; birth rate; recurrence 1. Introduction Malignant forms of germ cell ovarian tumors (GCT) and sex cord-stromal ovarian tumors (SCST) constitute a vast majority of non-epithelial ovarian cancers (NEOC); however, they account for approximately 5–10% of all ovarian malignancies [1–3]. The heterogeneity of NEOC is extraordinary, with a wide spectrum of clinical presentations, histologies, and Cancers 2023, 15, 4170. https://doi.org/10.3390/cancers15164170 https://www.mdpi.com/journal/cancers