Introduction/Background Endometrial carcinosarcoma (ECS) is an aggressive high-grade endometrial carcinoma that accounts for 15% of deaths from uterine malignancies. Nowadays, is considered a high-grade endometrial carcinoma with secondary sarcomatous trans-differentiation. It is not a single entity and depending on the type of carcinomatous (usually high-grade) and sarcomatous elements (homologous or heterologous) there are different histological subtypes. The combination of high-grade carcinoma and heterologous sarcomatous differentiation is associated with the worst prognosis.

The aim of this study is to present a descriptive analysis of ECS cases diagnosed at our Centre, analysing the prognostic factors and survival.

Methodology Retrospective study of 15 ECS cases diagnosed between 2008–2023. We present the epidemiology and clinical characteristics as well as pathological findings, 2-year and 5-year survival rate and overall survival (OS).

Results The average age of the patients (n=15) was 75.7 years (62–95 yrs). Of 15 cases diagnosed of ECS, the sarcomatous elements were homologous in 12 (75%) cases and 3 (25%) were heterologous tumours. The stage at diagnosis was early in 8 (53.3%) cases (FIGO I-II) and advanced in 7 (46.7%) cases (FIGO III-IV). Regarding treatment, 12 (80.0%) patients underwent surgery, of which 2 did not receive adjuvant treatment, 5 adjuvant radiotherapy, 1 chemotherapy and 5 chemo-radiotherapy (3 patients did not undergo surgery: 2 patients palliative care and 1 lost of follow-up before treatment). There were 10 recurrences and 2 disease progressions. OS was 12,5 months, 2-year survival rate was 15.3 months, and 5-year survival rate was 0. One patient died of other causes and one patient is alive and disease-free after 5 months of surgery.

Conclusion Despite the small number of cases in our cohort, ECS prognosis is extremely poor even in early stages. New targeted therapies (as immunotherapy) and specific guidelines for the management of ECS subtypes could improve its prognosis.

Disclosures This research received no external funding. The authors declare no conflict of interest.