Which phenotype corresponds to absence of ER, PR, and HER2 expression?

Which phenotype corresponds to absence of ER, PR, and HER2 expression?

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

Answer: (A)

Breast cancer subtypes are defined by receptor status for ER, PR, and HER2, which guides therapy choices. Absence of all three receptors—ER, PR, and HER2—defines the triple-negative phenotype. Without ER or PR, tumors won’t respond to endocrine therapies; without HER2, they won’t respond to HER2-targeted therapies. This makes triple-negative breast cancer the label for tumors that lack these receptors. In contrast, luminal A and luminal B cancers express estrogen receptor (and often progesterone receptor) and may have variable HER2 status, while HER2-enriched cancers overexpress HER2 and are typically ER/PR negative but HER2 positive, so they are not triple-negative.

Breast cancer subtypes are defined by receptor status for ER, PR, and HER2, which guides therapy choices. Absence of all three receptors—ER, PR, and HER2—defines the triple-negative phenotype. Without ER or PR, tumors won’t respond to endocrine therapies; without HER2, they won’t respond to HER2-targeted therapies. This makes triple-negative breast cancer the label for tumors that lack these receptors. In contrast, luminal A and luminal B cancers express estrogen receptor (and often progesterone receptor) and may have variable HER2 status, while HER2-enriched cancers overexpress HER2 and are typically ER/PR negative but HER2 positive, so they are not triple-negative.