Clinical outcomes after cystectomy or unilateral salpingo-oophorectomy for seromucinous borderline ovarian tumors: a single-center retrospective cohort study

Seromucinous borderline ovarian tumor (SMBT) is an uncommon subtype of borderline ovarian tumor characterized by Müllerian-type differentiation and frequent coexistence with endometriosis. Because of its rarity, its clinicopathological characteristics and the oncologic and reproductive outcomes after fertility-sparing surgery remain incompletely defined. To describe the clinicopathological characteristics and observed oncologic and reproductive outcomes of SMBT after cystectomy or unilateral salpingo-oophorectomy (USO). We retrospectively analyzed 186 patients with histologically confirmed SMBT. Postoperative imaging-detected adnexal lesions leading to repeat surgery and histologically confirmed borderline ovarian tumor recurrence were analyzed separately. Cystectomy and USO were compared using exploratory analyses, and a multivariable Cox model was used for the broader postoperative lesion outcome. Reproductive outcomes were evaluated among patients with documented fertility desire who underwent fertility-sparing surgery. The median age was 37.0 years and the median follow-up was 35.66 months. All patients had FIGO stage I disease, and pathologically confirmed endometriosis was present in 35.5%. Among 77 patients undergoing cystectomy and 52 undergoing USO, postoperative imaging-detected adnexal lesions leading to repeat surgery occurred in 40.3% and 44.2%, respectively (OR, 0.85; exact 95% CI, 0.39–1.84; P = 0.717). Final pathology showed non-borderline ovarian cystic lesions in 50 patients and histologically confirmed recurrence in four. Cystectomy was not significantly associated with the broader postoperative lesion outcome after adjustment (adjusted HR, 1.38; 95% CI, 0.79–2.41; P = 0.252). Histologically confirmed recurrence occurred in 2.6% after cystectomy and 3.8% after USO (OR, 0.67; exact 95% CI, 0.05–9.50; P = 1.000). Among 68 patients with documented fertility desire who underwent fertility-sparing surgery, documented pregnancy and live birth each occurred in 16/44 (36.4%) after cystectomy and 8/24 (33.3%) after USO (OR, 1.14; exact 95% CI, 0.36–3.80; P = 1.000). Histologically confirmed recurrence was uncommon during the available short- to intermediate-term follow-up, whereas postoperative adnexal lesions leading to repeat surgery were more frequent and were predominantly non-borderline cystic lesions. No statistically significant differences in histologically confirmed recurrence or documented reproductive outcomes were detected between cystectomy and USO. However, the limited number of recurrence events, unequal follow-up, non-random treatment allocation, and incomplete fertility-specific data preclude conclusions regarding equivalence, non-inferiority, or comparative long-term oncologic safety.