Abstract PS3-05-10: The Self-Declared White Ethnicity is Associated with the Presence of Pathogenic Variants in Brazilian Public Health Patients Undergoing Extended Multigene Panel Testing

Abstract Introduction: Breast cancer is the most common cancer among women in Brazil, with high mortality rates, especially in younger women. Hereditary factors, including mutations in BRCA1 and BRCA2, are responsible for a significant number of cases. The use of multigene panels for genetic testing has increased, though data on ethnically admixed populations remain limited. Objective: To evaluate the prevalence of pathogenic variants in a Brazilian public health population and their association with epidemiological variables. Methodology: This study involved women with a personal or family history of breast cancer. Blood samples were collected for genetic sequencing of 144 genes associated with hereditary syndromes. The study took place at the High-Risk sector of the Hospital da Mulher Prof. Dr. José Aristodemo Pinotti – CAISM, UNICAMP, between November 2021 and October 2022. Data were analyzed using next-generation sequencing (NGS) and statistical tests (Chi-Square, Fisher's Exact, Kruskal-Wallis, Bowker, McNemar, logistic regression) with significance set at p < 0.05. Results: Of the 364 participants, 85.9% had genetic variants, with 29.7% having pathogenic or likely pathogenic variants. White women (OR: 2.1; CI 1.31-3.36) and those with a personal history of breast cancer (OR: 1.90; CI 1.16-3.10) had significantly higher risks for these variants. The most commonly affected genes were BRCA1, BRCA2, TP53, PALB2, and MUTYH. Conclusion: The study revealed a high prevalence of pathogenic variants, highlighting the role of race and personal history in genetic predisposition to breast cancer. Citation Format: C. Alem, A. Cabello, b. N. Duarte, S. R. teixeira, T. Gaspar, A. viaro, D. I. Silva, M. L. Sousa, T. Cabello, S. Ramalho, L. R. Silva, C. Cabello. The Self-Declared White Ethnicity is Associated with the Presence of Pathogenic Variants in Brazilian Public Health Patients Undergoing Extended Multigene Panel Testing [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-05-10.