National patterns of care and cancer-specific outcomes of adjuvant treatment in patients with serous and clear cell endometrial carcinoma.

ABSTRACT

OBJECTIVES: To investigate outcomes of adjuvant therapy for serous and clear cell endometrial carcinoma, as prior studies are limited by sample size and/or patient heterogeneity. National guidelines permit substantial variations in treatment, suggesting the need for additional data. METHODS: Patients with FIGO stages I-III serous or clear cell uterine carcinoma who underwent at least total hysterectomy were identified in SEER-Medicare. Adjuvant external beam radiation, brachytherapy, and chemotherapy were determined using SEER fields and Medicare claims. The primary outcome was death from endometrial cancer (cancer-specific mortality [CSM]) evaluated using Gray's test (univariable analysis, UVA) and Fine-Gray regression (multivariable analysis, MVA). RESULTS: A total of 1789 patients (1437 serous, 352 clear cell) were identified. In stages I-II patients (n = 1188), brachytherapy was significant for survival in UVA (P = 0.03) and MVA (P = 0.02). Additionally, in the subset with serous histology (n = 947), chemotherapy was also significant in UVA (P = 0.002) and approached significance in MVA (P = 0.05). The 4-year CSM for stages I-II serous cancers was 25% without brachytherapy or chemotherapy, 15% with one, and 9% with both (P ≤ 0.05 for all pairwise comparisons). In stage III patients (n = 601), chemotherapy was significant in UVA (P = 0.002) and MVA (P = 0.006). Most (81%) patients underwent lymph node dissection, which predicted lower CSM in stage III (P = 0.001) but not stages I-II patients. CONCLUSIONS: Our results suggest brachytherapy benefits stages I-II serous/clear cell cancers, chemotherapy benefits stage III serous/clear cell cancers, and both chemotherapy and brachytherapy benefit stages I-II serous cancers.