Physicians use a staging method to classify all forms of breast cancer, including ductal carcinoma. This information helps them identify the best treatment options for a patient. The stages are:

• Stage 0. When the cancer is contained to the area where it began. Ductal carcinoma in situ (DCIS) is considered Stage 0.
  
  
• Stage I. When the cancer has spread beyond a breast duct, but not outside the breast. The tumor size at this stage is equal to or less than 1 inch in diameter (2 centimeters).
  
  
• Stage II. Tumors can range from less than 1 inch across (2 centimeters) to more than 2 inches across (5 centimeters). They may or may not have spread to the axillary (underarm) lymph nodes.
  
  
• Stage III. All types of stage III tumors are considered a locally advanced form of breast cancer. In these cases, the cancer has spread to the axillary lymph nodes, 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 in diameter (5 centimeters) to larger than 2 inches.
  
  
• Stage IV. Metastatic cancer is considered stage IV, which is cancer that has spread from the site of origin to other organs of the body. Frequent metastases sites for breast cancer are the bones, lungs, liver or brain.