Clinicopathological features, immunophenotyping, and immunohistochemical biomarkers associated with germline BRCA1/2 variants in breast cancer: a retrospective cohort of 265 patients.

Breast cancer (BC) progression and treatment response are influenced by germline BRCA1/2 (gBRCA) variant status. Carrying BRCA1/2 gene variants increases an individual's risk of developing breast cancer. With the advent of poly ADP-ribose polymerase (PARP) inhibitors, these patients may achieve disease control and effective treatment. However, the clinicopathological characteristics and immunophenotypes associated with this gene in breast cancer remain incompletely understood. A total of 265 patients with invasive breast cancer were retrospectively enrolled and tested for gBRCA variants. Germline pathogenic/likely pathogenic BRCA1/2 variants are associated with distinct clinicopathological features, triple-negative breast cancer (TNBC) enrichment, and adverse prognosis. Integrating BRCA1/2 testing with immunohistochemical (IHC) biomarkers (including programmed death-ligand 1(PD-L1) in TNBC) may help refine risk stratification and inform individualized therapy.