Endometrial cancer is the most common gynecologic malignancy and the fourth most common cancer in women. Its incidence and mortality are increasing, projected to become the sixth most common cancer by 2030. Most cases are endometrioid histology, but non-endometrioid histologies contribute significantly to mortality. The rise in obesity parallels the increase in endometrial cancer incidence. Data from the NPCR and SEER program show a 1.3% annual percent change in uterine cancer incidence between 2003-2019, with the largest increase in the US Hispanic population. Non-Hispanic Black women have the highest incidence and mortality rates and lower survival rates compared to White women. Previous research in Puerto Rico showed a significant increase in age-adjusted incidence rates of endometrial cancer from 1992 to 2003 for Puerto Ricans and Non-Hispanic Blacks. This study aims to monitor epidemiological trends in Puerto Rico and compare them to other US ethnic groups to identify potential disparities.

Existing literature highlights the increasing incidence and mortality of endometrial cancer, particularly its association with rising obesity rates. Studies have shown disparities in incidence, mortality, and survival rates across different racial and ethnic groups, with Non-Hispanic Black women experiencing poorer outcomes. Previous research on endometrial cancer in Puerto Rico indicated a significant increase in incidence rates from 1992 to 2003, particularly among Puerto Ricans and Non-Hispanic Blacks. The rising prevalence of obesity and diabetes in Puerto Rico, factors associated with endometrial cancer, necessitates further investigation into the epidemiological patterns and health disparities in this population compared to other US ethnic groups.

This study used a secondary data analysis comparing age-specific and age-adjusted incidence rates, mortality rates, and survival of endometrial cancer in Puerto Rico (PR) with Non-Hispanic Black (NHB), Non-Hispanic White (NHW), and US Hispanic women from 2000 to 2018. Data for PR was obtained from the Puerto Rico Central Cancer Registry (PRCCR), which uses SEER and NAAACR standards and has >95% completeness since 2010. US data was from the Surveillance, Epidemiology, and End Results (SEER) Program. Population data came from the Vintage 2019 estimates from the US Census Bureau and the Puerto Rico Demographic Registry. The analysis included women ≥19 years old with microscopically confirmed primary endometrial carcinoma. Incidence and mortality rates were calculated per 100,000 women ≥20 years old and age-adjusted to the 2000 US Standard Population. Annual Percent Change (APC) was calculated using SEER Software and NCI Joinpoint Regression software. Five-year relative survival rates were calculated for cases diagnosed between 2010 and 2014 with follow-up to 2019 for the PR population. The study was approved by the Institutional Review Board of the Comprehensive Cancer Center of the University of Puerto Rico.

Between 2014-2018, PR women had the highest endometrial cancer incidence rates (41.3 per 100,000), followed by NHW, NHB, and Hispanics. PR women under 65 had higher incidence rates than other groups. By stage, PR women had the lowest incidence of distant stage and the highest for localized stage. The APC for PR women aged 20-34 was 5.02% (p<0.05), the highest among all groups. PR women had the highest increase in incidence across all age groups, most significantly in the 35-49 age group (6.96%, p<0.05). NHB women had the highest overall mortality rates (12.5 per 100,000), but PR women had the highest mortality rates in the 20-34 and 35-49 age groups. The 5-year relative survival rate (RSR) for PR was 79.9%, slightly higher than the rate from 1992-2003. NHB women under 50 had worse survival outcomes than NHW women.

This study reveals significantly higher endometrial cancer incidence and mortality rates among younger Puerto Rican women compared to other groups. The high obesity rate in PR (77.4% overweight or obese in 2013, 37.5% obese in 2021) may be a contributing factor, along with decreased fertility rates and increased nulliparity. The significant APC in incidence rates for PR women aged 20-34 (5.02%) confirms previous findings. The higher rate of localized stage diagnosis in PR compared to the higher rate of distant metastasis in NHB contributes to the observed mortality disparities. Disparities may include access to care, socioeconomic factors, and possibly biological factors. The slightly improved 5-year survival rate in PR despite increased incidence suggests potential improvements in treatment or detection.

This study highlights substantial health disparities in endometrial cancer among young Puerto Rican women. Further research is needed to identify specific risk factors contributing to the increased vulnerability of this population. Public awareness campaigns focused on obesity as a risk factor and early detection are crucial.

One limitation is the lack of correction for hysterectomy rates in the analysis. Further studies are needed to investigate BMI, other risk factors, and clinical correlations with pathology biomarkers to fully understand the observed disparities.