Doctors need to know what stage your breast cancer is in to decide what treatment to recommend. The stage is based on the size and extent of your tumor, the number of nodes involved, and whether the cancer has spread. Your oncologist will be able to know your stage based on information gained from a variety of tests, including the biopsy and perhaps a lymph node biopsy. All things considered, the stage of a cancer is still more important in determining the treatment strategy than its grade.
The TNM System with Breast Cancer
The TNM System is a standard system for describing the extent of a cancer's growth. It is the most common system used to stage breast cancer. The International Union Against Cancer and the American Joint Committee on Cancer developed it. Here's what the letters stand for in the TNM System:
- T refers to the size of the tumor in the breast.
- N tells whether the lymph nodes in the area of the breast contain cancer.
- M tells whether the cancer has spread (metastasized) to other organs in the body, such as your bones, brain, liver, or lungs.
Numerical values, from 0 to 4, are assigned to the T, N, and M categories. Once your oncologist has determined your T, N, and M stages, this information is put together in what is called stage grouping, set by the American Joint Committee on Cancer (AJCC). The AJCC stage grouping is used to determine your overall disease stage.
Stage Groupings for Breast Cancer
These are the AJCC stage groupings for breast cancer. Each TNM category, with its assigned numerical value, falls into one of these stages.
- Stage 0 (early stage). This means that DCIS, LCIS, or Paget's disease of the nipple has been found. There is no actual tumor, and there are no signs of disease spreading to lymph nodes or tissue beyond the breast. With LCIS, you are at increased risk for breast cancer, but no cancer is actually present.
- Stage IA (early stage). No cancer cells are found in the lymph nodes or distant sites, and the tumor is no more than two centimeters (less than one inch) across.
- Stage IB (early stage). Tiny amounts of cancer cells are found in the lymph nodes but not in distant sites, and the tumor is no more than two centimeters (less than one inch) across.
- Stage IIA. These are cancers in which there is either no tumor or a tumor is less than two centimeters across, but cancer cells are in your lymph nodes. These are also cancers between two and five centimeters that have no lymph node involvement. The cancer has not spread to distant sites.
- Stage IIB. Two to five centimeters across, these cancers have spread to lymph nodes. Or the tumor is more than five centimeters (two inches) across, but it has not spread to the lymph nodes or to the chest wall or skin. The cancer has not spread to distant sites.
- Stage IIIA (advanced stage). This stage is also called locally advanced cancer. The tumor is not more than five centimeters (two inches) across, and the cancer in your underarm lymph nodes is extensive, or it has spread to other lymph nodes. Or the tumor is more than five centimeters (two inches) across, and it has spread to other lymph node areas but not to the chest wall or skin. The cancer has not spread to distant sites.
- Stage IIIB. This stage includes those cancers that have spread to the chest wall or skin and maybe to nearby lymph nodes. Inflammatory breast cancer is a type of locally advanced breast cancer in this stage unless it has spread to distant lymph nodes or organs.
- Stage IIIC. This stage includes tumors of any size and cancer in many different lymph nodes but not in distant sites.
- Stage IV. This is cancer that has spread to other organs and maybe to distant lymph nodes. It is called metastatic cancer. In this case, the size of the tumor and the extent of the spread to the lymph nodes are less important than the fact that cancer has spread from the breast to other organs of the body.