What Are the Stages of Breast Cancer?

Stages of cancer relate to how far the cancer has spread in your body. The higher the stage number, the more widespread is the cancer. These stages are important to determine the type of breast cancer treatment you will receive.
As part of determining your stage of cancer, your health care provider may check the lymph nodes in your armpit (called your axillary lymph nodes). If cancer spreads, it usually does so to these nodes first. There are two ways to check these nodes:

• Axillary lymph node dissection - The standard of practice for telling the stage of breast cancer has included the removal of about 10 to 25 axillary lymph nodes to help tell if the cancer has spread. This procedure is called an axillary lymph node dissection. But this procedure can have long-lasting side effects, including pain, numbness, swelling of your arm (called lymphedema), and limited motion of your shoulder.
• Sentinel lymph node biopsy - This procedure can prevent having to remove all the lymph nodes. Sentinel lymph node biopsy involves removing only a single lymph node (the sentinel lymph node), which is the first lymph node to drain excess fluid surrounding the cancer.
  
  Before surgery, blue dye, or a radioactive tracer, or both is injected near the cancer. The dye drains from the area containing the cancer into the nearby lymph nodes through the sentinel node. The node containing the dye is removed during surgery and checked under a microscope to see if it has cancer in it. Sentinel lymph node biopsy is becoming the standard way of determining whether cancer has spread to the lymph nodes in women with localized breast cancer.
  
  If you have cancer in your lymph nodes, health care professionals say you have node-positive breast cancer. If you do not have any cancer in your lymph nodes, they say you have node-negative breast cancer.
  
  Depending on the results, you may need more tests to see if the cancer has spread to other organs, such as your liver and bones. These may include blood tests, a chest x-ray, and scans, such as a computed tomography (CT), magnetic resonance imaging (MRI), or a bone scan.
  After your doctor has all of the test results, the stage of your cancer can be determined.

Stages of Breast Cancer

The different stages of breast cancer are:

• Stage 0 - (Ductal carcinoma in situ [DCIS]) - At this stage, cancer is found inside the ducts or the lobules of your breast and is very early in its development. About 15 percent to 20 percent of breast cancers are carcinoma in situ when they are found.
  
  Because this is very early cancer, it is sometimes called Stage 0. There are two types. The first is called ductal carcinoma in situ (DCIS) because it starts in the ducts of your breast. DCIS is sometimes called precancer because it can be the precursor to invasive breast cancer, but it is highly curable if treated early.
  
  The second type is lobular carcinoma in situ (LCIS). This type of breast cancer starts in the lobules and is associated with a higher risk of getting invasive breast cancer in either breast than DCIS. However, it is not considered a true breast cancer.
• Stage I - The cancer is 2 centimeters (three-fourths inch) or less in size and has not spread outside your breast.
• Stage IIA - The following describes the features of stage IIA: (1) No cancer is found in the breast, but cancer cells are found in one to three lymph nodes in your armpit (your axillary lymph nodes); or (2) the cancer is less than 2 centimeters (three-fourths inch) in size and is found in one to three lymph nodes; or (3) the tumor is larger than 2 centimeters and less than 5 centimeters, but hasn't spread to the lymph nodes.
• Stage IIB - The cancer is (1) between 2 and 5 centimeters and has spread to one to three underarm lymph nodes; or (2) the tumor is larger than 5 centimeters, but has not grown into the chest wall or spread to the lymph nodes or anywhere else.
• Stage IIIA - The cancer is (1) smaller than 5 centimeters and has spread to four to nine lymph nodes under the arm or to lymph nodes under the rib cage (internal mammary nodes); or (2) the cancer is larger than 5 centimeters and has spread to one to nine lymph nodes under your arm or to internal mammary nodes.
• Stage IIIB - The cancer has spread to tissue in your chest wall. It may not be in any lymph nodes or up to nine axillary lymph nodes and may or may not have spread to the rib cage lymph nodes.
• Stage IIIC - This stage is any size tumor that has spread to 10 or more axillary lymph nodes, or one or more clavicle lymph nodes, or to the rib cage lymph nodes. All on the same side as the original breast cancer with no spread to other parts of the body.
• Inflammatory breast cancer - Inflammatory breast cancer is typically classified as stage III, unless it has spread beyond the breast, in which case it is considered stage IV.
• Stage IV - The cancer has spread to distant parts of your body. These may include your liver, lungs, bones, or lymph nodes far from the breast.