Abstract A072: Genetic ancestry is related to potential sources of breast cancer health disparities among Colombian women
Authors: Serrano-Gómez Silvia J. , Rey-Vargas Laura , Bejarano Lina , Mejía-Henao Juan Carlos , Sanabria-Salas Maria Carolina 
Published: January 2023

Introduction: Socioeconomic disadvantages can contribute to breast cancer health disparities among populations. However, it has been shown that other factors related to the etiology of breast cancer and the biology of the tumor, might also act as determinants of health disparities, as they can impact the patients’ treatment. To date, the relationship between these factors with genetic ancestry in a highly admixed population from Latin-America, has not yet been explored. Based on this, we aimed to assess contributing factors to breast cancer health disparities according to genetic ancestry in Colombian patients from a national cancer reference center. Methods: We revised clinical-pathological and socioeconomic data from breast cancer patients diagnosed at the National Cancer Institute (NCI) of Colombia and classified variables into the following groups: etiology-related factors (e.g., age of diagnosis), tumor-biology factors (e.g., tumor size), and socioeconomic factors (e.g., health insurance), each of which reflects potential sources of racial/ethnic disparities of breast cancer. We also considered variables related to treatment administration (e.g., neoadjuvant therapy) as an indicator of disease management. We applied a Kruskal–Wallis test to assess differences in genetic ancestry fractions according to each of the variables distribution. Results: A total of 308 Colombian breast cancer patients were included. Etiology-related factors analysis showed higher European ancestry fraction in patients diagnosed at older ages (&gt;50 years: 50% vs. ≤50 years: 46%, p=0.017), and with smaller tumors (&lt;20mm: 52% vs. ≥20mm: 48%, p=0.038). Higher Indigenous American (IA) ancestry was observed in patients with HER2-positive tumors compared to HER2-negative cases (44% vs. 40%. p=0.011). Additionally, patients with higher IA ancestry were more frequently treated with neoadjuvant therapy (NAT) (43% vs. no-NAT: 40%, p=0.050). Moreover, socioeconomic variables showed that patients that benefit from the government public health insurance, known in Colombia as subsidized regime, and those who are covered under their relative’s health insurance, known as beneficiaries, have a higher IA ancestry (43% and 43%, respectively, vs. 37%, p=0.016), compared to patients that do afford their own health insurance (contributory regime in Colombia); conversely, these patients presented a higher European ancestry (55% vs. subsidized: 47% and beneficiaries: 49%, p=0.011). Conclusions: Our results indicate that genetic ancestry is related to several potential sources of breast cancer health disparities that cover from tumor-biology factors like tumor size and HER2 expression to socioeconomic determinants like health insurance affiliation regime. Consequently, it is possible that genetic ancestry may partially reflect some differences in the disease management and in healthcare attention given to breast cancer patients in Colombia.

Citation Format: Silvia J. Serrano-Gómez, Laura Rey-Vargas, Lina Bejarano, Juan Carlos Mejía-Henao, Maria Carolina Sanabria-Salas. Genetic ancestry is related to potential sources of breast cancer health disparities among Colombian women [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 A072.