Abstract A85: Receipt of adjuvant endometrial carcinoma treatment according to race: An NRG Oncology/Gynecologic Oncology Group 210 Study

Background: Black women diagnosed with endometrial cancer (EC) experience worse outcomes compared with white women. Differences in receipt of treatment are postulated to contribute to this disparity. While underuse of surgical treatment among black women is well documented, we know less about racial differences in adjuvant treatment. We therefore examined receipt of adjuvant treatment among black and white women in the NRG Oncology/Gynecology Oncology Group (GOG) 210 Study, a large prospective cohort of women with EC who received uniform surgical treatment but varying adjuvant therapy regimens. Methods: Our analysis included 615 black and 4,283 white women with EC who underwent either an abdominal hysterectomy or laparoscopic-assisted vaginal hysterectomy with bilateral salpingo-oophorectomy and lymph node dissection. At study enrollment, women completed a questionnaire that assessed race as well as risk factors for EC. Tumor characteristics were available from surgical pathology reports and a centralized review by pathologists with expertise in gynecologic cancers. Adjuvant treatment was documented at the time of the postoperative clinical visits and was categorized as none (54.3%), radiotherapy only (16.5%), chemotherapy only (n=15.2%), and radiotherapy and chemotherapy (14.0%). We used polytomous logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between race and receipt of adjuvant therapy in the overall study population and stratified by tumor subtype (combination of histology and grade) adjusted for age, income, education, and stage. Results: Black compared with white women had higher odds of receiving combination radiotherapy and chemotherapy compared to no adjuvant therapy (OR=1.35, 95% CI=1.01-1.79) but no difference in receipt of radiotherapy only (OR=0.95, 95% CI=0.72-1.25) or chemotherapy only (OR=0.88 (0.64-1.20) was observed. In tumor-subtype stratified models, black women diagnosed with low-grade endometrioid (OR=2.04, 95% CI=1.06-3.93) or serous tumors (OR=1.81, 95% CI=1.07-3.08) had higher odds of receiving radiotherapy and chemotherapy than white women, but race was not associated with receipt of radiotherapy and chemotherapy for women with high-grade endometrioid, carcinosarcoma, mixed-cell, or clear-cell tumors. Moreover, the tumor-subtype stratified analyses revealed no racial differences in receipt of radiotherapy-only or chemotherapy-only regimens. Conclusions: In this study of women with EC who received uniform surgical treatment, we observed racial differences in receipt of some adjuvant treatment regimens but not others. Among women with indolent (i.e., low-grade endometrioid) or aggressive (i.e., serous) tumors, black women had higher odds of receiving radiotherapy and chemotherapy compared to white women. Radiotherapy and chemotherapy treatment is potentially contraindicated for women with indolent tumors, which suggests a need to understand the reasons why clinicians might overprescribe these therapies for black women. Overall, our results suggest racial differences in receipt of radiotherapy and chemotherapy, but not for other regimens. Citation Format: Ashley Felix, David Cohn, Theodore Brasky, David Mutch, William Creasman, Premal Thaker, Joan Walker, Richard Moore, Shashikant Lele, Saketh Guntupalli, Levi Downs, Christa Nagel, John Boggess, Michael Pearl, Olga Ioffe, Wei Deng, Marcus Randall, Louise Brinton. Receipt of adjuvant endometrial carcinoma treatment according to race: An NRG Oncology/Gynecologic Oncology Group 210 Study [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A85.