Role of adjuvant radiotherapy modality on clinical outcomes for early-stage uterine carcinosarcoma.

Background: There are limited data around adjuvant radiotherapy following surgical management for patients with early-stage uterine carcinosarcoma (UCS). We compared outcomes for patients with early-stage UCS who underwent adjuvant chemotherapy (CT) and pelvic external beam radiotherapy (EBRT) vs. CT and vaginal brachytherapy (VBT) vs. radiation therapy (EBRT or VBT) alone.

Methods: A retrospective analysis was performed of patients diagnosed with FIGO stage I-II UCS from 2002 to 2020 who received adjuvant radiotherapy, with or without CT, following definitive surgery. Clinical and treatment characteristics and clinical outcomes were assessed. Kaplan-Meier method and log-rank test was used for clinical outcomes. Cox proportional-hazards modeling was used for multivariable analysis.

Results: 98 patients were analyzed, of whom 38 received CT + EBRT, 31 received CT + VBT, and 29 received RT-alone (18 EBRT, 11 VBT). For the CT + EBRT, CT + VBT, and RT-alone groups, median follow up was 93.5, 50.2, and 143.0 months, and 3-year PFS was 78.7 %, 67.6 %, and 58.2 %, respectively. CT + EBRT was associated with improved PFS compared to RT alone (p = 0.01), but not compared to CT + VBT (p = 0.22). There were 4 locoregional recurrences in the CT + EBRT group (10.5 %), 8 in the CT + VBT group (25.8 %), and 5 in the RT-alone group (17.2 %). On multivariable analysis, RT-alone trended towards shorter time to progression (TTP) compared to CT + EBRT (p = 0.05), with similar TTP compared to CT + VBT (p = 0.83).

Conclusions: In one of the largest retrospective cohorts of early-stage UCS, adjuvant CT + EBRT, but not CT + VBT, improved outcomes compared to RT-alone. Larger prospective studies are needed to investigate the role of different radiation modalities in UCS.