Breast cancer can start in the ducts or lobules of the breast
Sometimes cancer cells stay in the ducts and lobules of the breast. This is called non-invasive breast cancer. If the cancer cells spread into the surrounding tissue, this is called invasive breast cancer. The site where the cancer starts is called the primary cancer.
Sometimes, breast cancer cells travel in the bloodstream or lymphatic system to other parts of the body such as the bones or liver. This is called metastatic breast cancer (or secondary or advanced breast cancer).