How Breast Cancer Spreads
Cancer cells don’t behave like normal cells. Cancer cells differ from normal cells in the following ways.
Primary tumor
Over time, cancer cells form a mass called a primary tumor.
Invasive
Cancer cells can grow into surrounding tissues. Invasive breast cancer is breast cancer that has spread from the milk ducts or lobules into the breast tissue or nearby lymph nodes.
Metastasis
Unlike normal cells, cancer cells can spread and form tumors in other parts of the body. Cancer that has spread is called a metastasis.
In this process, cancer cells break away from the first (primary) tumor and travel through blood or lymph vessels to distant sites. Once in other sites, cancer cells may form secondary tumors.
- Cancer that has spread to a nearby body part such as the axillary lymph nodes is called a local metastasis. It might be referred to as local/regional disease or locally advanced.
- Cancer that has spread to a body part far from the primary tumor is called a distant metastasis.
Breast cancer can metastasize to the bones, lungs, liver, spine, or brain. Breast cancer that has metastasized to other parts of the body is still called breast cancer.
