P080: BRCA1 Germline Variant Driving a Case of Colon Cancer

Authors: F Sautto, R Khalife, C Colton, D Coppola, A Magliocco
Journal: Genetics in Medicine Open, 2023

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Abstract:

BRCA1 mutations can infer a homologous repair defect that results in increased lifetime incidence of breast and ovarian cancer. There is conflicting data with regards to whether BRCA1 mutation carriers have increased risk for colorectal cancer. There are suggestions that BRCA may play a driver role in development of colorectal cancer and could be an important marker for targeted chemotherapy in the form of poly-ADP ribose polymerase (PARP) inhibitors and Programmed death-ligand 1 (PD-L1) checkpoint inhibitors. One study found that homologous repair deficiency (HRD) and microsatellite instability (MSI) were mutually exclusive in comprehensive genomic analysis of a large cohort, with BRCA mutations being observed at higher frequencies in MSI high tumors with monoallelic bystander alterations likely caused by the tumor mutational burden (TMB). We present a case of colonic adenocarcinoma in a patient with molecular analysis of the tumor revealed a germline BRCA1 variant along with high MSI and high TMB.

https://www.gimopen.org/article/S2949-7744(23)00099-7/fulltext