American Board of Internal Medicine (ABIM) Certification Practice Exam

Which medication is commonly used to treat lytic bone metastases from breast cancer?

1. Risedronate

2. Denosumab

3. Exemestane

4. Trastuzumab

The correct answer is: Denosumab

Denosumab is the correct choice for treating lytic bone metastases from breast cancer due to its specific action as a RANK ligand inhibitor. In the context of breast cancer, lytic bone metastases can lead to significant skeletal complications such as pathological fractures and osteoporosis. Denosumab works by inhibiting the RANK/RANKL signaling pathway, which is vital for the formation, function, and survival of osteoclasts, the cells that break down bone. By preventing the activity of osteoclasts, Denosumab effectively reduces bone resorption and helps stabilize the bone structure, decreasing the incidence of skeletal-related events in patients with bone metastases. Other medications listed do have roles in cancer treatment, but they do not specifically address the management of lytic bone metastases. Risedronate is a bisphosphonate that can be used for the treatment of osteoporosis and for reducing skeletal complications in cancer, but is less effective in the specific context of breast cancer bone metastases compared to Denosumab. Exemestane is an aromatase inhibitor used primarily in hormone receptor-positive breast cancer but does not have any direct effect on bone metastases. Trastuzumab is a targeted therapy for HER2-positive breast cancer and