Abstract C066: Effects of race, ethnicity, and country of origin on incidence and survival in breast cancer

Abstract Purpose: Breast cancer (BC) is the leading cause of cancer related deaths in Hispanic women. Hispanics make up an estimated 82% of the U.S./Mexico border, a region of socioeconomic inequity and barriers to healthcare access. Identifying disparities affecting BC incidence and overall survival (OS) is a priority for optimizing care in this medically underserved population. We hypothesized that differences in ethnicity, border proximity, birthplace, BC subtype, and treatments are associated with poor outcomes. Methods: Data from the Texas Cancer Registry was used to construct Kaplan-Meier curves of OS by ethnicity, birthplace, subtype (Luminal A, Luminal B, HER2, Triple Negative (TNBC)), age group (18-39, 40-69, >70 years), and treatments. Other covariates included rurality, insurance status, socioeconomic status, and comorbidities. Crude and adjusted variable effects on OS were analyzed with Mantel Haenszel and Cox regression methods. Results: Hispanic BC patients were diagnosed at a younger age than non-Hispanic whites (NHW) (57.2 versus 61.1 years). Hispanic ethnicity reduced the risk for luminal A and TNBC (HR 0.90, and 0.87, p<0.01), whereas non-Hispanic blacks (NHB) had higher risk for luminal A, luminal B, and TNBC (HR 1.39, 1.48, and 1.18, p<0.01). A birthplace outside of Texas resulted in a lower risk of developing any subtype of BC (p<0.001). In general, NHBs had more risk to develop any type of BC than NHWs (p<0.0001). Hispanic ethnicity is associated with a significantly decreased risk of mortality in TNBC than NHWs (HR .87, p=.011). TNBC Hispanics born in Mexico have a lower risk of death in comparison to NHWs (HR .93, p=.036), while Hispanics born in the U.S. have a higher risk (HR 1.13, p=.06). Lower HRs were observed for patients in El Paso versus the rest of Texas (HR 0.73, p<0.0001), and hormone therapy, chemotherapy, and radiation treatment (HR 0.92, 0.96, 0.82, p<0.0001). Surgical procedures were not associated with mortality. Median survival (MS) for Hispanic patients compared to NHW was 16 versus 14 years, p<0.0001. Patients in El Paso compared to the rest of Texas had MS 8 versus 6 years, p<0.0001. Hispanics and NHWs with luminal A and luminal B had similar OS. Non-significant differences in OS were noted for HER2. No difference in OS was found for Hispanics and NHWs with TNBC, while OS was higher in El Paso compared to the rest of Texas (MS 4 versus 2 years, p=0.024). HER2 and TNBC Hispanics 18-39 years had worse OS (p=0.0193 and p<0.0001). Those ages 40-69 years had similar OS for HER2 compared to NHWs, but improved OS in TNBC (p<0.0001). Conclusions: Hispanics had comparable OS to NHW. Those in the border region seem to have improved OS versus the rest of Texas. Race/ethnicity and birthplace are significant predictors of survival in TNBC. Hispanic ethnicity is generally associated with better prognoses in TNBC; however, Hispanics born in the U.S. have lower survival rates in comparison with Hispanic patients born in Mexico. NHB patients are associated with significantly worse OS in all BC subtypes. Citation Format: Alfonso E. Bencomo-Alvarez, Vutha Nhim, Luis Alvarado, Mayra A. Gonzalez, Michelle Kilcoyne, Alok K. Dwivedi, Shrikanth S. Gadad, Anna M. Eiring. Effects of race, ethnicity, and country of origin on incidence and survival in breast cancer [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 C066.