Uterine Cancer Incidence Trends and Five-Year Relative Survival by Race/Ethnicity and Histology Among Women Under 50 Years.

ABSTRACT

BACKGROUND: Uterine cancers diagnosed before age 50 years are increasing in the U.S., but changes in clinical characteristics and survival over time across racial/ethnic groups have not been previously described. OBJECTIVES: To investigate age-adjusted, hysterectomy corrected incidence rates and trends, and five-year relative survival rates of uterine cancer in women aged <50 years, overall and stratified by race/ethnicity and histology. STUDY DESIGN: We included microscopically confirmed uterine cancer cases (diagnosed 2000-2019) in women aged 20-49 years from the Surveillance, Epidemiology, and End Results Program (SEER 22). Age-adjusted incidence and 5-year relative survival rates, and 95% confidence intervals were computed using SEER*Stat and compared across time periods (2000-2009 and 2010-2019). Incidence rates were adjusted for hysterectomy prevalence using Behavioral Risk Factor Surveillance System data, and trends were computed using the Joinpoint regression program. RESULTS: We included 57,128 uterine cancer cases. The incidence of uterine cancer increased from 10.1 per 100,000 in 2000-2009 to 12.0 per 100,000 in 2010-2019, increasing at an annual rate of 1.7%/year for the entire period. Rising trends were more pronounced among women <40 years (3.0%/year and 3.3%/year in 20-29 and 30-39 years, respectively) than in those 40-49 years (1.3%/year), and among underrepresented racial/ethnic groups (Hispanic 2.8%/year, Non-Hispanic, [NH]-Black 2.7%, NH-Asian/Pacific Islander [PI] 2.1%) than in NH-White (0.9%/ year). Recent (2010-2019) incidence rates were highest for endometrioid (9.6 per 100,000), followed by sarcomas (1.2), and non-endometrioid subtypes (0.9). Rates increased significantly for endometrioid subtypes at 1.9%/year from 2000-2019. Recent endometrioid and non-endometrioid rates were highest in NH-Native American/Alaska Native [NA/AN] (15.2 and 1.4 per 100,000), followed by Hispanic (10.9 and 1.0), NH-Asian/PI (10.2 and 0.9), NH-White (9.4 and 0.8), and lowest in NH-Black women (6.4 and 0.8). Sarcoma rates were highest in NH-Black women (1.8 per 100,000). The five-year relative survival remained unchanged over time for women with endometrioid (from 93.4% in 2000-2009 to 93.9% in 2010-2019, p≥0.05) and non-endometrioid subtypes (from 73.2% to 73.2%, p≥0.05) but decreased for women with sarcoma from 69.8% (2000-2009) to 66.4% (2010-2019, p<0.05). CONCLUSIONS: Uterine cancer incidence rates in women <50 years have increased from 2000 to 2019 while survival has remained relatively unchanged. Incidence trends can be primarily attributed to increasing rates of cancers with endometrioid histology, with the greatest increases observed among NH-Black, Hispanic, and NH-Asian/PI. Sarcomas, while much rarer, were the second most common type of uterine cancer among women <50 years and have poor prognosis and apparent decreasing survival over time. Rising rates of uterine cancer and the distinct epidemiologic patterns among women <50 years highlight the need for effective prevention and early detection strategies for uterine cancer in this age group.