Breast cancer is staged using the numbers 0 through IV. 

• Stage 0 These cancers are called Noninvasive, or in situ (in one place). Although Stage 0 cancers do not have the ability to invade normal breast tissue or spread to other parts of the body, it is important to have them removed because they eventually can become invasive cancers. 

• Stage I to IV  These cancers are Invasive Tumors that have the ability to invade normal breast tissue or spread to other areas. A stage I cancer is small and well localized and has a high cure rate. But the higher the stage number, the lower the chances of cure. By stage IV, the cancer has spread beyond the breast to other organs, such as to bones, lungs or the liver. Although it is not possible to cure cancer at this stage, it may still respond well to various treatments, which could effectively shrink and control the cancer for an extended period of time.