Radiation therapy improves disease-specific survival in women with Stage II endometrioid endometrial cancer—Brachytherapy may be sufficient

Purpose: To evaluate disease-specific survival (DSS) outcomes in Stage II endometrioid endometrial cancer (EC) patients based on pathology and treatment information including adjuvant radiotherapy and lymph node assessment. Methods and Materials: Using the Surveillance, Epidemiology, and End Results database, 2877 patients with Stage II EC diagnosed between 2004 and 2012 treated with radiation were identified. DSS was determined for different modalities of radiation. Kaplan–Meier estimates of survival and Cox regression modeling were used to explore the risk associated with various factors on DSS. Results: The 4-year DSS for the study population was 90%. Radiation was associated with improved 4-year DSS when compared to no radiotherapy (p = 0.03). Patients with Grade 2 and 3 tumors had improved 4-year DSS with radiation (94% vs. 90%, p = 0.02 and 81% vs. 73%, p = 0.15), respectively, but no differences in DSS when vaginal brachytherapy alone was compared with external beam alone or both. Patients with Grade 2 (p = 0.002) and Grade 3 (p < 0.001) tumors without a lymph node dissection (LND) had worse DSS compared to patients with any LND. Patients with Grade 3 tumors without an LND who received radiation showed improved DSS (p = 0.008). Multivariable analysis revealed that age >60 years (p < 0.001), Grade 3 (p < 0.001), no radiotherapy (p = 0.05), and no LNDs (p < 0.001) were significant prognostic factors for worse DSS. Conclusions: Adjuvant radiation, whether delivered by brachytherapy or external beam radiation, is associated with improved DSS in Stage II EC patients with high-grade tumors, therefore brachytherapy may be sufficient.