What is breast cancer metastasis?
When cells in the body grow out of control, it is called cancer. A growth of cancer cells is called a tumor. Breast cancer is metastatic when the cancer spreads beyond the tumor in the breast and the lymph nodes in the nearby armpit. This happens when cells shed by the tumor spread (or metastasize) to other parts of the body through the bloodstream or lymph system. After the cancer spreads, it can form new tumors in other parts of the body. These tumors are called metastases. As the cancer spreads through the blood, it most commonly travels to the bones of the pelvis, spine, upper arms and legs, ribs, and skull. Metastases are also commonly found in the liver, lungs, and brain. Metastases happen most often within 3 years after initial treatment for breast cancer, but they can occur many years, even decades, later.
