Which of the following is an example of endocrine therapy used for hormone receptor-positive breast cancer?

• A. Doxorubicin
• B. Bevacizumab
• C. Tamoxifen
• D. Pembrolizumab

Answer: (C)

Endocrine therapy targets the hormonal drivers of growth in hormone receptor–positive breast cancer by blocking estrogen signaling. Tamoxifen is a classic endocrine therapy because it acts as a selective estrogen receptor modulator: it binds to estrogen receptors in breast tissue and blocks estrogen from stimulating cancer cell proliferation. This reduces the risk of recurrence and helps control disease in patients whose tumors depend on estrogen to grow. It’s commonly used as adjuvant therapy and is suitable for many premenopausal patients, with specific roles also in certain postmenopausal settings.

The other options are not endocrine therapies. Doxorubicin is a cytotoxic chemotherapy that damages DNA to kill cancer cells, not by blocking hormone signaling. Bevacizumab inhibits angiogenesis by targeting VEGF, not hormone pathways. Pembrolizumab is an immunotherapy that enhances the immune system’s ability to attack cancer, not hormone receptor signaling.