Breast cancer most commonly spreads first to the nearby lymph nodes, particularly the sentinel lymph node located in the underarm (axillary) area
. This is usually the first site outside the breast where cancer cells are found because the lymphatic system drains fluid from the breast to these nodes, allowing cancer cells to travel there. After the lymph nodes, the most common site for breast cancer to spread is the bones. Breast cancer can metastasize to any bone but most often affects the ribs, spine, pelvis, and long bones in the arms and legs
. Bone metastasis occurs in over half of metastatic breast cancer cases and is the most frequent first distant site of spread
. Other common sites where breast cancer spreads include the lungs, liver, and brain, but these tend to occur after lymph nodes and bones
. The pattern of spread typically starts locally in the breast, then to lymph nodes, and then to distant organs such as bones and lungs. In summary:
- First spread: nearby lymph nodes, especially axillary (underarm) lymph nodes
- Most common distant metastasis site: bones (ribs, spine, pelvis, long bones)
- Other common sites: lungs, liver, brain
This progression reflects how breast cancer cells travel through lymphatic vessels and blood vessels to reach other parts of the body
