Abstract P3-12-24: Landscape of germline BRCA1 and BRCA2 mutations in breast cancer in Peru
Authors: Pinto Joseph A , Ferreyra Yomali , Cock-Rada Alicia M , Doimi Franco , Casas Jhoysi , Araujo Jhajaira , Rosas Gina , Bravo Leny , Belmar-López Carolina 
Published: March 2022

Abstract
BACKGROUND: Breast cancer (BC) is the most common cancer and the second leading cause of cancer-related deaths worldwide. Mutations in tumor suppressor genes BRCA1 and BRCA2 are the most common cause of hereditary breast and ovarian cancer. Additionally, carriers of germline BRCA1/2 mutations also have an elevated risk of other malignancies. Identification of mutations within these genes is essential for determining early cancer detection and risk-reducing strategies in carriers and establishing a therapeutic approach in breast cancer patients. The aims of this study were to evaluate the prevalence and spectrumof germline BRCA1 and BRCA2 variants in peruvian breast cancer patients. METHODS: Patients with HER2Neu negative BC referred to ONCOGENOMICS laboratory from 2019 to2021 to assessed poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor treatment were included in the study. Blood samples were collected to assess the status of germline BRCA1 and BRCA2. Next Generation Sequencing (NGS) was performed using the Ampliseq for Illumina BRCA panel and run on the Illumina MiSeq. The Human Genome Variation Society (HGVS) nomenclature guidelines (http://varnomen.hgvs.org/) were used to annotate identified variants and the ClinVar database (www.ncbi.nlm.nih.gov/clinvar/) was used to determine the clinical significance of all reported variants. Current American College of Medical Genetics (ACMG) guidelines were also used for further classification. RESULTS: A total of 155 HER2Neu negative BC cases were evaluated. Median age at BRCA1/2 evaluation was 51 (23-82) years, 78.1% (121) were negative HR status (triple-negative BC, TNBC); 21.9% (34) were positive HR status; 33.5% (52) were clinical stage III and 66.5% (103) were clinical stage IV. Most patients were from Lima-Callao (65.8%) followed by patients from the coast (23.9%), highlands (9%) and rainforest(1.3%). Only 18.7% of patients were from public health centers. The prevalence of pathogenic (P) and likely pathogenic (LP) variants in BRCA1/2 was 13.5% (21) (13 in BRCA1 and 8 in BRCA2). The pathogenic variant in BRCA1 c.2105dupT (p.Leu702Phefs*10) was found in 3 cases (2 Lima-Callao and 1 coast). All variants identified in BRCA1 were in TNBC. In BRCA2, half of pathogenic variants were found in TNBC. The prevalence of variants of uncertain significance (VUS) was 6.4% (10). In BRCA2, we identified 7 VUS and the variant c.5465A&gt;T (p.Asn1822Ile) was found in 3 cases with positive HR status. Only one VUS was found in BRCA1. CONCLUSION: BRCA1 and BRCA2 germline mutations were identified in 13.5% of peruvian HER2Neu negative BC patients. A higher rate of P/LP variants was found in BRCA1. TNBC patients demostrated a higher prevalence in BRCA1 variants.
Citation Format: Joseph A Pinto, Yomali Ferreyra, Alicia M Cock-Rada, Franco Doimi, Jhoysi Casas, Jhajaira Araujo, Gina Rosas, Leny Bravo, Carolina Belmar-López. Landscape of germline BRCA1 and BRCA2 mutations in breast cancer in Peru [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-24.