Objectives Endometrial serous carcinomas (ESC) hold a poor prognosis, even at early stages. This study evaluates the outcomes and prognostic factors for stage I (FIGO 2018) ESC treated with adjuvant chemotherapy and vaginal vault brachytherapy (VBT).

Methods Patients were selected through a database of patients treated with hysterectomy for stage I ESC between 2007 and 2019 at the Centre Hospitalier de l’Université de Montréal. The intended adjuvant treatment had to be 6 cycles of Carboblatin and Paclitaxel and VBT. Time to events were analyzed by Kaplan-Meier. Cox regression analysis was performed to identify prognostic factors.

Results A total of 76 patients with stage IA (N=64) and IB (N=12) ESC were included in this study. Median age at diagnostic was 67. Median follow up was 60 months. 5-year overall survival (OS) and progression-free survival (PFS) were 83% and 79.5%. Nine patients relapsed, 3 with local recurrence, 3 with regional recurrence and the other 3 with distant recurrence. Amongst the known prognostic factors included in univariate analysis, positive peritoneal washing and advanced age were significant prognostic factors for OS (p<0.0001 and p=0.013, respectively). Age, isthmus invasion, deep myometrial invasion and positive peritoneal washings were significant prognostic factors for PFS (p=0.049, p=0.024, p=0.022 and p<0.0001, respectively).

Conclusions In stage I ESC, adjuvant chemotherapy and VBT was associated with good oncologic outcomes. Advanced age and positive peritoneal washings were significant prognostic factors for OS. Further studies are needed to assess whether a subgroup of patients would benefit from treatment intensification or de-escalation.