What is the first route of metastasis for breast cancer?

Breast cancer typically spreads through the lymphatic system, and the axillary lymph nodes are generally the first site of metastasis for the majority of breast cancers. This occurs because the lymphatic drainage from the breast primarily leads to the axillary lymph nodes, which receive lymphatic fluid containing cancer cells from the breast tissue.

When cancer cells invade the local lymphatic vessels, they often travel to the axillary nodes before they can reach other areas in the body. The presence of cancer cells in these nodes is crucial for staging the disease and affects treatment decisions. Therefore, detecting disease in the axillary lymph nodes is a common factor that influences the prognosis and management of breast cancer.

While the other routes of metastasis mentioned can occur, they typically follow after involvement of the axillary lymph nodes, making them secondary pathways rather than the primary route of metastasis.