Once a diagnosis has confirmed the existence of breast cancer, the next step is to determine the stage of cancer. The stage is based on the size of the tumor and whether or not the cancer has spread. Staging often involves additional x-rays and lab tests. These tests can show whether the cancer has spread and, if so, to what parts of the body. When breast cancer spreads, cancer cells are often found in lymph nodes under the arm. In some cases, surgery may be required to accurately determine the stage of the cancer.
The stages of breast cancer are:
Stage 0 (Pre-cancer)
Stage 0 breast cancer, which includes carcinoma in situ, means that the carcinoma has not spread beyond its point of origin.
The encouraging news is that the survival rate for women treated for Stage 0 breast cancer is over 99 percent.
In Stage I breast cancer, the tumor is small, and may even be too small to see. It is invasive, meaning that it has spread to other breast tissue. The cancer may or may not have spread to the lymph nodes close to the breast, but the cancer has not spread to any other part of the body.
The five-year survival rate for women treated for Stage I breast cancer remains very high at 98 percent.
In Stage II breast cancer, there may be no tumor found in the breast, but cancer can be found that has spread to axillary lymph nodes or nodes close to the breastbone. Axillary nodes are nodes found in a chain from under the arm to above the collarbone.
There might also be a tumor between two and five centimeters in the breast with small cancers in some of the lymph nodes. Or the tumor could be larger than five centimeters with no cancer in the nodes.
In Stage IIIA, cancer has spread to four to nine axillary nodes or to nodes near the breastbone but not to other parts of the body. Or there could be a tumor larger than five centimeters and cancer that has spread to three axillary nodes or to nodes near the breastbone.
In Stage IIIB breast cancer, the tumor has spread to the chest wall or to the skin of the breast causing an ulcer or swelling. It may also have spread to axillary nodes but not to other parts of the body.
In Stage IIIC, cancer of any size has spread to at least 10 axillary nodes. It may also have spread to the skin of the breast or breast wall, but not to distant parts of the body.
Stage IV represents the most advanced form of breast cancer. In this case, cancer cells have metastasized, which means the cancer has spread to distant parts of the body, such as bones, organs, or lymph nodes located far from the breast. Treatment may help shrink or control the cancer temporarily, but it usually will not completely cure the cancer. At this stage, symptom relief often becomes a priority.