Abstract PS3-05-17: Prevalence of BRCA 1/2 mutation among breast cancer patients in Kenya

Abstract Background: Breast cancer (BC) is the most common cancer in Kenya, with patients being diagnosed a decade earlier than in the USA. Patients harbouring BRCA1/2 mutations have aggressive disease, but paradoxically respond well to tailored treatments such as poly ADP-ribose polymerase (PARP) inhibitors. However, BRCA testing is not accessible for most patients in Africa; thus, the prevalence largely remains unknown, with very scant published literature from Sub-Saharan Africa showing a wide variation from 2% up to 17%. We hereby report the prevalence of BRCA1/2 mutations for patients screened in the first six months in a recently opened independent referral lab in Kenya. Methods: The BC patients with high-risk clinical features such as young age, triple-negative breast cancer (TNBC), bilateral BC, and familial history of breast cancer who had been referred for germline (gBRCA 1/2) or somatic (sBRCA 1/2) testing were screened. After consent, patients' samples, either peripheral blood or Formalin-Fixed Paraffin-Embedded, were tested for BRCA 1/2 mutations using the Oncomine BRCA Research Assay. Gene variant ID, variant class, and variant allele frequency, among others, were reported. Only patients with a confirmed BC diagnosis and de-identified data were included in this analysis. Results: In the six months, 42 patients were screened for BRCA 1/2 mutation. Of which 14 females had confirmed BC diagnosis, and their median age is 47 years (range: 29 - 70). The majority (10 out of 14) had triple-negative breast cancer, one with bilateral breast cancer, while another had metastasis to the ovary. The family history was not provided for any of these patients. The prevalence of BRCA 1/2 mutations was 21% among the patients who underwent germline testing (n=12). Two had pathogenic variants in BRCA1, while one in BRCA2. The most common mutation was indels. Moreover, three patients had a BRCA 2 variant of uncertain significance (VUS). The most common mutation was missense. Conclusion: In this study, the prevalence of BRCA 1/2 mutations among BC patients in Kenya is 20%. To our knowledge, this is among the first works on BRCA testing in BC reported from Kenya, and increased availability and accessibility to oncogenetic testing will not only lay a foundation for future research work but also facilitate better management of BC patients with PARP inhibitors. Citation Format: A. Athman Omar, R. Mukadam, A. Kalebi. Prevalence of BRCA 1/2 mutation among breast cancer patients in Kenya [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 PS3-05-17.