Breast cancer is when the cells under one or both breasts grow out of control. Those cells may spread beyond your breasts. When that happens, the cancer is called metastatic.
Did You Know?
Different types of breast cancer grow and spread at different rates. Some take years to spread beyond your breast, while others grow and spread quickly.
Breast cancer usually begins either in your glands that make milk (called lobular carcinoma) or the ducts that carry it to the nipple (called ductal carcinoma). It can grow larger in your breast and spread to nearby lymph nodes or through your bloodstream to other organs. The cancer may grow and invade tissue around your breast, such as your skin or chest wall.