Abstract B021: Early onset uterine corpus cancer incidence rates and 5-year relative survival by histologic subtype and race/ethnicity among women aged 20-49 years
Authors: Wijayabahu Akemi T. , Clarke Megan A. 
Published: March 2024

Abstract
Purpose: Uterine cancer, including early onset cases, is increasing among all women, particularly in minority populations. Despite nearly 25% of cancers occurring in younger women, changes in tumor characteristics (e.g., histology) by race/ethnicity remain poorly understood. We examined incidence rates and 5-year relative survival of uterine cancer among women aged 20-49, overall and by race/ethnicity and histology. Methods: We used the Surveillance, Epidemiology, and End Results Program (SEER 22) Research Plus Data, representing 47.9% of the total U.S. population. We included women aged 20-49 years with microscopically confirmed malignant uterine cancer (diagnosed 2000-2019) to calculate age-adjusted incidence and age-standardized 5-year relative survival (2000-2018) overall and by race/ethnicity and histology. Time trends were described across two time periods: 2000-2009 and 2010-2019. All analyses were conducted using SEER*Stat; incidence rates were presented for per 100,000 population. Results: We included 57,128 cases (55% Non-Hispanic [NH]-White, 9% NH-Black, 10% NH-Asian/Pacific Islander [PI], and 25% Hispanic). From the period of 2000-2009 to 2010-2019, the proportion of cases that were 20-29 and 30-39 increased by 1% and 4%, respectively. Overall, incidence increased over time for all women (8.7 in 2000-2009 to. 10.4 in 2010-2019), and increases were observed for both endometrioid and non-endometrioid subtypes. In the most recent period, rates were highest for endometrioid subtypes (8.4), followed by sarcomas (1.0), and non-endometrioid subtypes (0.7). Rates for endometrioid and non-endometrioid cancers were highest in Hispanics (9.9 and 0.8) and NH-Asian/Pacific Islanders (9.7 and 0.8), respectively and lowest in NH-Blacks (5.5 and 0.6). Rates of sarcomas were highest in NH-Blacks (1.5). 5-year relative survival remained relatively unchanged over time in most racial/ethnic groups, except NH-Blacks experienced slight improvement (57% to 60%). In terms of histology, survival increased for endometrioid (87% to 89%) and non-endometrioid cases (54% to 58%) and decreased for sarcomas (46% to 42%). Conclusions: Early onset uterine cancer is rising in all women, and for both endometrioid and non-endometrioid subtypes. Of interest is the differences in the rates by histology when compared the full U.S. population: Among women aged &lt;50 years, rates of uterine sarcomas were higher compared to non-endometrioid subtypes. These findings are concerning given that sarcomas are associated with poor prognosis and were the only cases to show decreased 5-year survival in our analysis. While rates of non-endometrioid subtypes are known to be higher among NH-Black women in the U.S., we did not observe a striking racial difference among early onset cases. In fact, NH-Black women had the lowest rates of endometrioid and non-endometrioid subtypes, but highest rates of sarcomas compared to others. Next step for this analysis is hysterectomy correction, which, while expected to be relatively lower among women aged&lt;50 years, is known to vary by race/ethnicity.
Citation Format: Akemi T. Wijayabahu, Megan A. Clarke. Early onset uterine corpus cancer incidence rates and 5-year relative survival by histologic subtype and race/ethnicity among women aged 20-49 years [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr B021.