BACKGROUND: Black women diagnosed with endometrial carcinoma have a higher risk of recurrence compared with white women. Higher recurrence risk among black women is due, in part, to a greater frequency of aggressive tumor characteristics including non-endometrioid histologies and advanced stage tumors. The risk of recurrence for black and white women within distinct tumor groupings has not been well-examined due to low numbers of black women and under-representation of aggressive histologic subtypes in single institution studies. Therefore, we examined the association between self-reported race and recurrence risk stratified by histologic subtype in the NRG Oncology/Gynecology Oncology Group (GOG) 210, a prospective observational study that enrolled 6,124 newly diagnosed endometrial carcinoma patients between 2003 and 2011.

METHODS: We restricted this analysis to 618 black and 4,316 white women with endometrial carcinoma. At study enrollment, women completed a questionnaire that assessed risk factors for gynecologic cancers. Recurrence, defined as evidence of disease following complete response to primary therapy, was abstracted from medical records. Tumor characteristics were available from surgical pathology reports and a centralized review by pathologists with expertise in gynecologic cancers. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between race (black vs. white) and recurrence risk in models stratified by histologic subtype (low-grade endometrioid, high-grade endometrioid, serous, mixed epithelial, carcinosarcoma, clear cell) and adjusted for stage (I, II, III, IV), age at diagnosis (continuous), and adjuvant therapy (none, chemotherapy, radiation, chemotherapy and radiation, unknown). We also examined income ($20,000-$39,999, $40,000-$69,999, ≥$70,000) and education (high school/GED, some college/technical school, college graduate/beyond) as potential mediators of the association between race and endometrial carcinoma recurrence risk using the Baron-Kenny method. Median follow-up time was 5 years.

RESULTS: Black women were more frequently diagnosed with non-endometrioid (52.9% vs. 31.8%) and advanced stage (Stage III or IV: 29.0% vs. 21.1%) tumors compared with white women. Recurrence was documented in 26% of black and 17% of white endometrial carcinoma patients. In histologic subtype-stratified models adjusted for stage, age, and adjuvant therapy, a higher risk of recurrence was noted in black women with low-grade endometrioid (HR=1.65, 95% CI=1.07-2.54), mixed epithelial (HR=1.75, 95% CI=1.13-2.71), or carcinosarcomas (HR=1.55, 95% CI=1.03-2.31) compared with white women. No significant race-recurrence relationships were observed among women diagnosed with high-grade endometrioid, serous, or clear cell tumors. After adjustment for income and education, the association of black race and recurrence risk remained elevated, but was not statistically significant: low-grade endometrioid (HR=1.52, 95% CI=0.97-2.38), mixed epithelial (HR=1.56, 95% CI=0.98-2.50), and carcinosarcoma (HR=1.48, 95% CI=0.98-2.25). Further, neither income nor education were significantly associated with recurrence risk in the multivariable models.

CONCLUSIONS: Our study provides evidence that racial disparities in endometrial carcinoma recurrence risk vary by histologic subtype. Socioeconomic factors do not explain black-white differences in endometrial carcinoma recurrence risk. Future studies exploring the role of biological factors and post-diagnosis surveillance contributing to racial differences in endometrial carcinoma recurrence are warranted.

Citation Format: Ashley S. Felix, Theodore Brasky, David Cohn, Scott McMeekin, David Mutch, Creasman William, Premal Thaker, Joan Walker, Richard Moore, Shashikant Lele, Saketh Guntupalli, Levi Downs, Christa Nagel, John Boggess, Michael Pearl, Olga Ioffe, Kay Park, Shamshad Ali, Louise Brinton. Endometrial carcinoma recurrence in black and white women in the NRG Oncology/Gynecologic Oncology Group 210 trial. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr C44.