Utilization and survival outcomes of sequential, concurrent and sandwich therapies for advanced stage endometrial...

To determine the impact on overall survival (OS) of different modalities of adjuvant therapy for the treatment of stage III endometrial cancer (EC), by histology.

Stage 3 endometrioid (EAC), serous (SER), clear cell (CC), and carcinosarcoma (CS) patients who underwent primary surgical staging from 2000 to 2013 were identified in SEER-Medicare. Adjuvant therapy was defined by a 4-arm comparator grouping (none; RT only; CT only; combination RT), as well as by an 8-arm comparator grouping (none; RT only; CT only; concurrent CT-RT; concurrent CT-RT then CT; Serial CT-RT; serial RT-CT; sandwich). Modality of RT and CT were analyzed using Kaplan-Meier estimates, log rank tests, and multivariable cox modeling.

Of 2870 cases identified (1798 EAC, 606 SER, 118 CC, 348 CS), 31.5% received no adjuvant therapy. The remainder received RT or CT alone, concurrent RT-CT, serial or sandwich modalities. OS differed by adjuvant therapy in adjusted and unadjusted models, when combining all histologies, and when stratifying by histology using both the 4-arm, and 8-arm comparator analyses (log rank p < .05, all). By histology, in adjusted analyses, sandwich modality had the greatest improvement in OS for endometrioid, but pairwise comparisons did not identify a superior chemotherapy-based regimen. For serous and clear cell, the greatest improvement in OS was seen with concurrent RT-CT, and for carcinosarcoma, CT alone.

OS for advanced EC significantly differs by histology and mode of adjuvant therapy. Future studies should evaluate the efficacy of combination-based adjuvant therapy versus chemotherapy alone, by histologic subtype and molecular signature.