Longitudinal treatment sequencing and post-progression care in ovarian carcinosarcoma: a single-center real-world cohort study

Ovarian carcinosarcoma (OCS) is a rare, aggressive malignancy for which evidence on treatment beyond first-line therapy remains limited. We characterized longitudinal treatment sequencing, later-line treatment depth, post-progression care, contemporary systemic-therapy exposure, and cohort-level survival outcomes. We retrospectively reconstructed 160 longitudinal clinical episodes for 44 patients with primary OCS diagnosed between April 2014 and October 2025, using prespecified treatment-line and maintenance rules. Missing data were not imputed. Two gynecologic pathologists independently reviewed final pathology reports and immunohistochemical results recorded in those reports; slides were not independently re-reviewed. Kaplan–Meier methods estimated progression-free survival (PFS) and overall survival (OS). A sensitivity analysis added after the first review used a common recorded diagnosis-date PFS origin; this estimate is emphasized for descriptive interpretation. Of 44 patients, 30 underwent primary debulking surgery, 9 interval debulking surgery, and 5 no surgery. Systemic treatment was given to 41/44 (93.2%); 34/41 treated patients (82.9%) received a taxane–platinum first-line backbone. Maintenance was documented in 8/44 (18.2%). Confirmed second-line and third-line-or-later treatment occurred in 17/44 (38.6%) and 9/44 (20.5%), respectively. Overlapping bevacizumab, immune checkpoint inhibitor, and PARP inhibitor exposures occurred in 20/44 (45.5%), 10/44 (22.7%), and 6/44 (13.6%) patients. Among the 21 patients with explicitly documented first progression, 19/21 (90.5%) received systemic treatment: 17/19 (89.5%) started a new episode and 2/19 (10.5%) only continued a regimen. Median follow-up was 37.6 months. The post-review common diagnosis-origin analysis yielded a median PFS of 10.7 months (95% CI, 7.0–17.8); the prespecified strategy-specific-origin analysis yielded 11.9 months (95% CI, 6.6–17.8). Median OS was 23.1 months (95% CI, 12.6–41.0). In this cohort, platinum-taxane therapy was the predominant first-line backbone; fewer patients had confirmed later-line treatment, and maintenance and post-progression pathways were heterogeneous. These findings describe real-world treatment sequencing and post-progression management in OCS.