Abstract A104: Race, clinical stage, and mortality among rural breast cancer patients in Bahia, Brazil

Abstract

Breast cancer is the most frequently diagnosed malignancy and one of the leading causes of cancer-related mortality among women worldwide. Previous studies have shown that Black women are more likely to present with the triple-negative subtype, which is associated with a poorer prognosis, in addition to experiencing greater socioeconomic vulnerability and barriers to healthcare access, factors that may influence clinical outcomes of the disease. We conducted a study to investigate the association between self-reported race, histological type, immunohistochemical subtype, breast cancer stage at diagnosis and mortality, among patients treated at an oncology referral center in the Recôncavo region of Bahia, Brazil. Patients diagnosed with breast cancer and treated between 2012 and 2020 at the High-Complexity Oncology Unit (UNACON) in Santo Antônio de Jesus, Bahia, Brazil were included in this analysis. Self-reported race or skin color was obtained from medical records, as well as clinical variables including clinical stage and mortality. Associations between categorical variables were assessed using Pearson's chi-square test. A total of 412 women were included in this analysis. Most patients, 76.7%, self-identified as Black or Brown. The main histological type was invasive ductal carcinoma for 91.1% of Black/Brown patients and 89.7% of White patients (p=0.912). No differences in subtype by race were observed in this population. Luminal A subtype was the most frequent subtype for Black/Brown (36.6%) and White (46.6%) women. It is noteworthy that the prevalense of triple-negative breast cancer (TNBC) in this population was 23.6% for Black/Brown patients and 20.7% for White patients. We found no difference by race for stage at time of diagnosis, 55.5% of Black/Brown breast cancer patients were diagnosed with early-stage disease, versus 60.3% of White patients (p=0.430). Similarly, we found no association with mortality, 6.8% death occurred among Black/Brown breast cancer patients versus 6.9% among White (p=0.981). While other studies have observed variations in these clinical outcomes by race, we did not find a difference in this population. We uncover a higher prevalence of TNBC when comparing to other countries or regions in Brazil. Further studies will explore these trends further, to better understand their impact on disease outcomes and trajectory. João Neiva, Sibele Tozzeto, Kim J. Erfani, Moises Fernandes, Matheus Daltro, Leticia Tedesco, Breno Menezes, Gabriela Sodre, Lissette Delgado-Cruzata. Race, clinical stage, and mortality among rural breast cancer patients in Bahia, Brazil [abstract]. In: Proceedings of the 19th AACR Conference on the Science of Cancer Health Disparities; 2026 Oct 18-21; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2026;35(10 Suppl):Abstract nr A104.