GSOR21 Presentation Time: 12:10 PM

Purpose Brachytherapy remains a critical component of locoregional therapy for many women with gynecologic cancers. Other groups have demonstrated racial disparities in the utilization of brachytherapy. Specifically, black women with locally advanced cervical cancer are less likely to receive brachytherapy compared to non-black women. We hypothesized that similar disparities may exist for the utilization of vaginal brachytherapy (VBT) for women who meet PORTEC-2 criteria for high-intermediate risk (HIR) endometrial cancer. Materials and Methods Using the Surveillance, Epidemiology, and End Results (SEER) database, we identified patients who were diagnosed with endometrial cancer between 2011 to 2018, who met PORTEC-2 criteria for HIR disease (age 60 or greater with 1) FIGO stage IC (1988) and grade 1-2 disease or 2) FIGO stage IB (1988) and grade 3 disease). We limited our analysis to the year following the initial PORTEC-2 publication (2010) and beyond in order to allow for adoption into routine clinical practice. The impact of race and ethnicity on utilization of VBT versus external beam radiation therapy (EBRT) was analyzed on univariate and multivariate analyses (binary logistic regression, with significance assumed if p≤0.05), as was the impact of marital status, United States (U.S.) Census Bureau region, and whether or not a lymph node dissection was performed. Results A total of 2,182 patients were included in the analysis with a median age of 68 (range 60-97). The majority of patients were White (77.3%), married (50.8%), resided in the Western U.S. (45.1%), diagnosed with adenocarcinoma (97.2%), underwent lymph node dissection (84.7%), and received VBT (75.5%). On UVA, patients who were Hispanic (HR 1.58, CI 95% 1.15-2.16, p=0.005) and Asian or Pacific Islanders (HR 1.47, CI 95% 1.01-2.15, p=0.046) were less likely to receive VBT compared to White patients. There was a non-significant trend for Black patients (HR 1.43, 95% CI 0.98-2.08, p=0.066). Patients in the Southern (HR 1.69, CI 95% 1.24-2.31, p=0.001), Western (HR 1.7, CI 95% 1.31-2.20, p<0.001), and Pacific (HR 2.89, CI 95% 1.09-7.64, p=0.032) U.S. Census regions were less likely to receive VBT compared to the Northeast. Those who were divorced were more likely to receive VBT (HR 0.65, 95% CI 0.43-0.98, p=0.038). Finally, those patients who underwent lymph node dissection were more likely to receive VBT on UVA (HR 0.28, CI 95% 0.22-0.36, p<0.001). On MVA, patients who were Hispanic (HR 1.43, CI 95% 1.01-2.03, p=0.046), lived in the Southern (HR 1.82, CI 95% 1.30-2.55, p=0.001), Western (HR 1.61, CI 95% 1.21-2.14, p=0.001), or Pacific regions (HR 3.04, CI 95% 1.05-8.78, p=0.04) were less likely to receive VBT. Although it did not meet statistical significance, there was a trend for decreased utilization of VBT for Asian or Pacific Islanders (HR 1.45, CI 95% 0.94-2.25, p=0.094) and Black patients (HR 1.42, CI 95% 0.94-2.15, p=0.099), potentially a reflection of small patient numbers. Lastly, patients who underwent lymph node dissection were more likely to receive VBT on MVA (HR 0.27, CI 95% 0.21-0.35, p<0.001). Conclusions Brachytherapy remains a critical component of locoregional therapy for many women with endometrial cancer. VBT provides a significant improvement in local control in the pelvis with an improved toxicity profile compared to EBRT. Efforts should be made to make VBT available to those women in which it is clinically indicated, with apparent disparities based on the patient's race, ethnicity, and/or their geographic location within the U.S. in the setting of HIR disease. These disparities may have been further exacerbated during the ongoing COVID-19 pandemic, which has been shown in other settings to widen many pre-existing healthcare disparities.