Abstract C119: Rising incidence and racial disparities of early-onset endometrial cancer in the United States, 1995-2018
Authors: Habeshian Talar S. , Liu Lihua , Zhang Juan-Juan , Du Margaret , De Vivo Immaculata , Setiawan Veronica W. 
Published: January 2023

Abstract
BACKGROUND: Endometrial cancer (EC) is the most common gynecologic cancer and the fourth most common cancer among women in the United States (US). Although early-onset endometrial cancer (EOEC, diagnosed under age 50) is relatively uncommon, several studies have reported the incidence of EOEC has been increasing in recent decades. Because few studies have examined differences in incidence trends across race/ethnicity between EOEC and late-onset endometrial cancer (LOEC, diagnosed at age 50 or older), we compared the incidence trends between EOEC and LOEC in the US by race/ethnicity across two decades. METHODS: We used the CiNA Analytic File, 1995-2018, Public Use, obtained from the North American Association of Central Cancer Registries (NAACCR) and identified 930,176 invasive endometrial cancer cases (ICD-O-3 site code C54.1, excluding histology codes 9050-9055, 9140, and 9590-9992), of which 12.6% were EOEC and 87.4% LOEC. We examined the characteristics of these cases including race/ethnicity, year of diagnosis, tumor stage and grade by EOEC and LOEC status. We calculated the yearly race/ethnicity-specific age-adjusted incidence rates (AAIR) and the average annual percent change (AAPC) in the AAIRs for EOEC and LOEC respectively. RESULTS: Compared with LOEC cases, women with EOEC were less likely to be non-Hispanic (NH) White, more likely to be Hispanic or NH Asian/Pacific Islander (API), and less likely to have advanced stage or poorly differentiated grade. The AAIRs were highest in NH Whites in 1995 for both EOEC and LOEC. By 2018, the highest AAIR was found in Hispanics for EOEC and in NH Blacks for LOEC, resulting from faster increases in EC risk among the non-white groups. AAIRs for EOEC and LOEC increased over the study period, with the overall AAPC being three times as high for EOEC as LOEC (AAPC 1.72 vs. 0.57). For EOEC, the largest increases were observed in NH Blacks (AAPC=3.52) followed by Hispanics (AAPC=2.77) and NH API (AAPC=2.06). For LOEC, the largest increases were observed in NH APIs (AAPC=2.42) followed by NH Blacks (AAPC=2.28) and Hispanics (AAPC=1.71). For both EOEC and LOEC, the AAPCs were highest in NH Blacks and lowest in NH Whites. CONCLUSIONS: The faster increases in EOEC incidence among NH Black, Hispanic, and NH API women likely reflect racial/ethnic differences in the prevalence and trends of endometrial cancer risk factors. This indicates that these higher-risk populations might benefit from targeted surveillance and interventions. Future studies should evaluate whether these differences across race/ethnicity are attributable to specific tumor characteristics, biomarkers, or other sociodemographic factors.
Citation Format: Talar S. Habeshian, Lihua Liu, Juan-Juan Zhang, Margaret Du, Immaculata De Vivo, Veronica W. Setiawan. Rising incidence and racial disparities of early-onset endometrial cancer in the United States, 1995-2018 [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C119.