Platinum free interval and clinical benefit of the second-line chemotherapy in recurrent uterine and ovarian carcinosarcoma: a retrospective cohort analysis.

Objective: Uterine and ovarian carcinosarcomas (OCSs) are rare and aggressive neoplasms. We assessed whether progression free survival after initial treatment (PFS1) was associated with the clinical benefit of chemotherapy after progression, estimated as overall survival (OS) after progression/relapse.

Methods: All consecutive patients treated with chemotherapy for stage I-IV uterine/OCS in Cochin University Hospital between 2010 and 2022 were included in this retrospective cohort. Association between PFS1 and OS after progressive disease (PD) was determined by Cox regression. Optimal PFS1 threshold for OS after PD prediction was determined by a time-dependent receiver operating characteristic-curve analysis.

Results: Forty patients treated for endometrial (n=32) or OCS (n=8) were included. Median PFS1 and OS after PD were 16 months 95% confidence interval (95% CI=11-not available [NA]) and 6 months (95% CI=2-15). In patients who relapsed/progressed (n=20), OS after PD was anticipated by PFS1 (Pearson r=0.61; area under the curve=0.79; 95% CI=0.6-1). At the threshold of PFS1 ≤/>9 months (n=6/n=7), median OS post PD were 2 months (0.1-NA) and 15 months (6-NA), for patients treated with platinum/anthracycline based chemotherapy in second line. Patients receiving best supportive care alone (n=7) had a median OS post PD of 8 months (1.3-NA).

Conclusion: Our results highlight that a subgroup of carcinosarcomas patients exhibits a durable benefit from chemotherapy in the relapse settings, and suggest the use of PFS1, as a proxy of platinum-sensitivity, to select patients who might derive higher clinical benefit of a 2nd line of chemotherapy.