American Board of Internal Medicine (ABIM) Certification Practice Exam

Which class of drugs is used for the treatment of hormone receptor-positive metastatic breast cancer?

1. Monoclonal antibodies

2. Antiestrogens

3. Cytotoxic agents

4. Immune checkpoint inhibitors

The correct answer is: Antiestrogens

The therapy for hormone receptor-positive metastatic breast cancer primarily revolves around the use of antiestrogens. This class of drugs works by blocking the effects of estrogen in the body. Since many breast cancers grow in response to estrogen, antiestrogens can be crucial in controlling tumor growth and progression in patients with hormone receptor-positive tumors. Tamoxifen is a well-known example of an antiestrogen that binds to estrogen receptors and prevents estrogen from promoting tumor cell proliferation. In contrast, monoclonal antibodies are typically employed in targeted therapies for specific breast cancer subtypes, like HER2-positive breast cancer, rather than for hormone receptor-positive tumors. Cytotoxic agents are used in chemotherapy but are not specifically aimed at addressing hormone receptor status. Immune checkpoint inhibitors can be effective in certain cancers, but their primary utility in breast cancer is largely focused on triple-negative tumors rather than those that are hormone receptor-positive. Therefore, antiestrogens are the preferred treatment modality for managing hormone receptor-positive metastatic breast cancer, helping to reduce the risk of disease progression.