17P Gynaecologic carcinosarcomas (GCS)’s chemotherapy landscape: A retrospective analysis from Hospital Clinico San Carlos (HCSC), academic, referral centre for rare gynaecological malignancies in Madrid (Spain)

Gynaecologic carcinosarcomas (GCS) are rare cancers with poor prognosis. From 2003 onwards, GCS are no longer considered sarcomas but epithelial carcinomas, thus shifting the chemotherapy used in their multidisciplinary management. We aim to analyse the chemotherapy regimens used in GCS at our institution and patient's outcomes. Retrospective analysis of 57 GCS patients (pts) treated in HCSC from 1995-2003 and 2003-2022. Median age at diagnosis: 65 years (range 30-90); ECOG 0 63%. Primary disease: uterus 80.7%, ovary 17.5% or vaginal stump 1.8%. FIGO 2018 staging at diagnosis: I 40.4%, II 14%, III 22.8% and IV 22.8%. Carboplatin (C) and paclitaxel (T) were used initially in 50% of pts (57% adjuvant, 14.2% neoadjuvant and 19% fist line), from 2003, and as a retreatment (monotherapy, CT, or in combination with epirubicin, pegylated liposomal doxorubicin, bevacizumab, gemcitabine or ifosfamide) 10 times. Other drugs used as first strategy were anthracyclines, ifosfamide, cisplatin, cyclophosphamide, gemcitabine, docetaxel and in following lines dacarbazine, etoposide, bevacizumab, methotrexate, trabectedin, megestrol, niraparib and dostarlimab (Table). 11 pts relapsed after a complete response: local 45.5%, lymph node 18.1%, peritoneal 36.4%, visceral 18.2%, lung 10%. After a median follow-up of 20,67 months, median overall survival (mOS) 25.23 months (95% CI, 9-41.5 months) and median progression free survival (mPFS) 16.03 months (95% IC, 7-25 months). Pts treated from 2003 have better mOS than those treated before 2003 (40.5 vs. 9.7 months, p 0.034). Table: 17PIntention of initial chemotherapy treatment in the two cohorts regarding FIGO 2018 staging and outcomesFIGO 2018 stageNo treatmentAdjuvantNeoadjuvantFirst lineTotal ptsDiagnosed <2003I-III235Response2 PD3 CR (2 maintained, 1 relapsed)IV224ResponseNE2 PDDiagnosed >2003I-III9262239Response4 CR (2 maintained, 2 relapsed) 3 PD 2 NE22 CR (16 maintained, 6 relapsed) 4 PD2 RC (2 relapsed)2 PDIV2169Response2 PD1 PD1 CR (maintained) 5 PD Open table in a new tab We have used different chemotherapy regimens in GCS, more liberal use of adjuvant therapy, being CT the main regimen from 2003 onwards concurring with mOS improvement.