Triple negative breast cancer is characterized by absence of which receptor combination?

• A. ER and HER2
• B. ER and PR
• C. HER2 and PR
• D. ER only

Answer: (A)

Triple-negative breast cancer is defined by the lack of expression of the three receptors used to guide therapy: estrogen receptor (ER), progesterone receptor (PR), and HER2. This means the tumor does not rely on hormonal signaling or HER2-driven growth, so there are no targeted hormone therapies or HER2-directed treatments available for it. In the context of the options, none lists all three receptor negatives, which is why TNBC is best understood as negative for ER, PR, and HER2. Often, tests will confirm absence of all three to establish the triple-negative status; if any one of them is positive, the tumor would not be classified as triple-negative. Clinically, this absence shapes treatment choices and prognosis because it limits targeted therapy options to chemotherapy rather than hormone- or HER2-based strategies.