Which subtype is associated with BRCA1 in breast cancer?

• A. Hormone receptor-positive
• B. Triple-negative breast cancer
• C. HER2-enriched
• D. Luminal A

Answer: (B)

The question tests the link between BRCA1 mutations and breast cancer biology. BRCA1-associated tumors are characteristically triple-negative, meaning they typically lack estrogen receptor, progesterone receptor, and HER2 expression. This occurs because BRCA1 loss leads to defects in homologous recombination DNA repair, promoting a basal-like, high-grade phenotype that often presents with a triple-negative profile.

Because these cancers don’t express hormone receptors or HER2, they don’t respond to endocrine therapies or HER2-targeted drugs, shaping treatment toward chemotherapy regimens and the use of PARP inhibitors that exploit the DNA repair deficiency. In contrast, BRCA2-associated cancers tend to be hormone receptor-positive and fall into luminal subtypes rather than the triple-negative group.