Objective The aim of this retrospective population-based study was to investigate the oncologic safety of fertility-sparing surgery (FSS) for premenopausal women with malignant sex cord-stromal tumors (SCSTs) confined to the ovary.

Methods A cohort of women aged 18 to 49 years and diagnosed with a stage I malignant SCST between 1984 and 2013 was drawn from the National Cancer Institute's Surveillance, Epidemiology, and End Results database. Based on site-specific surgery codes, women who had FSS, defined as unilateral oophorectomy/tumor resection without hysterectomy, and definite surgery were identified. Cancer-specific survival and overall survival were evaluated after generation of Kaplan-Meier curves, whereas comparisons between the 2 groups were made with the log-rank test.

Results A total of 255 women who met the inclusion criteria were identified; 161 (63.1%) underwent FSS whereas 94 (36.9%) had definitive surgery (bilateral salpingo-oophorectomy and hysterectomy). Median follow-up was 104 months. Cancer-specific survival (P = 0.015) but not overall survival (P = 0.76) was superior for women who had definite surgery.

Conclusions In this retrospective population-based cohort of premenopausal women with SCSTs confined to the ovary, FSS was associated only with a worse long-term cancer-specific survival compared with definitive surgery. Women undergoing FSS for early stage SCSTs should be extensively counseled and closely monitored.