Which endocrine therapies are used for hormone receptor-positive breast cancer?

• A. Bevacizumab
• B. Tamoxifen or aromatase inhibitors
• C. Doxorubicin
• D. Pembrolizumab

Answer: (B)

In hormone receptor–positive breast cancer, the main treatment goal is to shut down estrogen signaling that drives tumor growth. Tamoxifen works by binding to the estrogen receptor in breast tissue and blocking estrogen from activating it, acting as an estrogen receptor antagonist there. Aromatase inhibitors reduce estrogen production by inhibiting the enzyme aromatase, which converts androgens to estrogen; this lowers circulating estrogen levels, and is especially effective in postmenopausal patients.

Other options listed do not target the hormonal driver: Bevacizumab is an anti-angiogenic agent, doxorubicin is a cytotoxic chemotherapy, and pembrolizumab is an immune checkpoint inhibitor. Therefore, tamoxifen or aromatase inhibitors are the endocrine therapies used for hormone receptor–positive breast cancer.