Racial and Ethnic Differences in Endometrial Cancer

Introduction: Endometrial cancer (EC) is the fourth most frequently diagnosed and the most common gynecologic cancer among American women. Past research suggests that racial/ethnic differences in EC outcomes exist; however these differences were almost exclusively examined in non-Hispanic White (NHW) and non-Hispanic Black (NHB) women. Asians and Hispanics represent the fastest growing minority populations in the United States, yet most investigations have failed to include them in their analyses. In addition, previous research has generally presented results for overall EC, although recommended treatment regimens vary by histologic subtype and there is evidence that subtype-specific survival differences exist. The goal of this research was to assess whether racial/ethnic differences in stage at diagnosis, treatment modalities and 5-year overall survival existed and explore what factors mediated these differences. Methods: The purpose of the first aim was to assess racial/ethnic differences in tumor, sociodemographic and treatment facility characteristics for Type 1 - low-grade endometrioid carcinomas (LGEC) and Type 2 EC - high-grade endometrioid carcinomas (HGEC), clear cell carcinomas (CCC) and serous carcinomas (SC). In addition, the goal of this aim was to determine whether subtype-specific racial/ethnic differences in stage at diagnosis between minority women and NHW existed. The main purpose of our second aim was to assess whether subtype-specific racial/ethnic differences existed in receipt of EC treatment, defined as surgery, radiation therapy and chemotherapy. The secondary goal of aim 2 was to assess the relative contribution of hypothesized mediators related to tumor characteristics, socio-economic and treatment facility factors on the detected racial/ethnic differences in receipt of treatment. The final aim was to assess whether subtype-specific racial/ethnic differences in overall five-year EC survival existed and explore whether the relative contribution of hypothesized mediators related to tumor characteristics, socio-economic factors, receipt of treatment and treatment facility factors on the detected differences. Results: In our first aim, we found that compared to NHW women, NHB women are significantly more likely to be diagnosed with aggressive EC subtypes. The results from our second aim showed that NHB women were the only minority group that had higher odds of not receiving surgical treatment than NHW, across all EC subtypes. Moreover, NHPI had five times higher odds of not receiving surgical treatment for SC than NHW. When assessing racial/ethnic differences in the receipt of radiation therapy and chemotherapy, we demonstrated that NHAIAN diagnosed with SC had higher odds of not receiving radiation therapy than NHW. Moreover, NHB women diagnosed with CCC had higher odds and NHA diagnosed with LGEC had lower odds of not receiving chemotherapy than NHW. In addition, the results of the mediation analyses showed that racial/ethnic differences in receipt of surgical treatment in women diagnosed with LGEC, HGEC and SC were partially mediated by the socio-economic (SE) domain. With respect to survival, NHB women diagnosed with LGEC, HGEC and SC had a lower overall 5-year survival than NHW. Additionally, NHA diagnosed with LGEC and Hispanics diagnosed with HGEC had a higher overall 5-year survival than NHW women. Lastly, the results from our mediation analyses demonstrated that receipt of surgical treatment and the SE domain contributed to NHB-NHW differences in overall 5-year survival in women diagnosed with LGEC and HGEC. Discussion: Subtype-specific racial/ethnic differences in stage at diagnosis, receipt of treatment and 5-year overall survival in women diagnosed with EC exist. These differences can be attributed to several factors, including a lack of knowledge about EC symptoms, refusal of surgery by women of lower socio-economic status (SES), and structural and social barriers present in areas of lower SES. Interventions to address the detected disparities could consist of efforts to improve the timeliness of diagnosis by raising the awareness about EC symptoms, to increase knowledge about the necessity of EC surgery in women who are likely to refuse treatment and to assist women of lower SES overcome barriers to accessing health services present in the area they live in. These interventions could be carried out within the framework of a patient navigation project or with the aid of community/social workers.