Orthopaedic Nurses Certification Board (ONCB) Metabolic/Inflammatory/Tumors Practice Exam

How does breast cancer typically metastasize to bone?

1. Direct extension of the primary tumor

2. Hematogenous spread of the primary tumor

3. Lymphatic dissemination

4. Lytic dissemination

The correct answer is: Lymphatic dissemination

When considering how breast cancer typically metastasizes to bone, it is important to understand the common pathways through which cancer spreads from its original site. Breast cancer most often disseminates via hematogenous spread, meaning that cancer cells travel through the bloodstream to reach distant sites, such as the bones. In this process, circulating tumor cells infiltrate the blood vessels and eventually lodge in the bone marrow or bone tissue, where they can establish secondary tumors. Lymphatic dissemination is a significant method by which breast cancer spreads initially, often leading to involvement of regional lymph nodes, but it is not the predominant pathway for metastasis to the bone. Instead, lymphatic routes primarily facilitate local spread. Direct extension of the primary tumor is more relevant for nearby structures rather than distant metastasis to bone. Lytic dissemination is a descriptive term that refers to the destructive process that occurs once the cancer has metastasized to bones, which is not a mechanism of spread itself. Overall, hematogenous spread stands out as the key process for how breast cancer cells reach the bone, leading to the establishment of bone metastases.