Physicians use a staging method to classify breast cancer diagnoses. This information allows them to choose the best treatment options based on the stage and type of cancer. The stages are as follows:

• Stage 0. Includes ductal and lobular carcinoma in situ (noninvasive cancer)

• Stage I. When the cancer has spread beyond a milk duct or lobe, but not outside the breast. The tumor size for this stage is equal to or less than 1 inch across (2 centimeters [cm]).
  
  
• Stage II. Like Stage I, Stage II is considered an early stage of breast cancer. Tumors can range from 1 inch across (2 cm) to more than 2 inches across (5 cm). They may or may not have spread to the axillary lymph nodes.
  
  
• Stage III (A-C). This is considered a locally advanced form of breast cancer. It has spread to the axillary lymph nodes, to tissues near the breast (such as the skin or chest wall) or to lymph nodes inside the chest wall. Tumors can range from smaller than 2 inches (5 cm) to larger than 2 inches.
  
  
• Stage IV. Metastatic cancer, which is cancer that has spread to other more distant organs of the body. Frequent metastatic sites for breast cancer are the bones, lungs, liver or brain. Stage IV is also the classification given to inflammatory breast cancer or breast cancer that has spread to the lymph nodes in the neck near the collarbone.