The following definition of the stages of breast cancer comes from the National Cancer Institute.
These are the stages of breast cancer:
Stage 0
Stage 0 is sometimes used to describe abnormal cells that are not invasive cancer. For example, Stage 0 is used for ductal carcinoma in situ (DCIS).
DCIS is diagnosed when abnormal cells are in the lining of a breast duct, but the abnormal cells have not invaded nearby breast tissue or spread outside the duct. Although many doctors don't consider DCIS to be cancer, DCIS sometimes becomes invasive breast cancer if not treated.
Stage I
Stage I is an early stage of invasive breast cancer. Cancer cells have invaded breast tissue beyond where the cancer started, but the cells have not spread beyond the breast. The tumor is no more than 2 centimeters (three-quarters of an inch) across.
Stage II
Stage II is one of the following:
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The tumor is no more than 2 centimeters (three-quarters of an inch) across. The cancer has spread to the lymph nodes under the arm.
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The tumor is between 2 and 5 centimeters (three-quarters of an inch to 2 inches). The cancer has not spread to the lymph nodes under the arm.
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The tumor is between 2 and 5 centimeters (three-quarters of an inch to 2 inches). The cancer has spread to the lymph nodes under the arm.
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The tumor is larger than 5 centimeters (2 inches). The cancer has not spread to the lymph nodes under the arm.
Stage III
Stage III is locally advanced cancer. It is divided into Stage IIIA, IIIB and IIIC.
- Stage IIIA is one of the following:
- The tumor is no more than 5 centimeters (2 inches) across. The cancer has spread to underarm lymph nodes that are attached to each other or to other structures. Or the cancer may have spread to lymph nodes behind the breastbone.
- The tumor is more than 5 centimeters across. The cancer has spread to underarm lymph nodes that are either alone or attached to each other or to other structures. Or the cancer may have spread to lymph nodes behind the breastbone.
- Stage IIIB is a tumor of any size that has grown into the chest wall or the skin of the breast. It may be associated with swelling of the breast or with nodules (lumps) in the breast skin:
- The cancer may have spread to lymph nodes under the arm.
- The cancer may have spread to underarm lymph nodes that are attached to each other or other structures. Or the cancer may have spread to lymph nodes behind the breastbone.
- Inflammatory breast cancer is a rare type of breast cancer. The breast looks red and swollen because cancer cells block the lymph vessels in the skin of the breast. When a doctor diagnoses inflammatory breast cancer, it is at least Stage IIIB, but it could be more advanced.
- Stage IIIC is a tumor of any size. It has spread in one of the following ways:
- The cancer has spread to the lymph nodes behind the breastbone and under the arm.
- The cancer has spread to the lymph nodes above or below the collarbone.
Stage IV
Stage IV is distant metastatic cancer. The cancer has spread to other parts of the body, such as the bones or liver.
Recurrent cancer
Recurrent cancer is cancer that has come back after a period of time when it could not be detected. Even when the cancer seems to be completely destroyed, the disease sometimes returns because undetected cancer cells remained somewhere in your body after treatment.
It may return in the breast or chest wall. Or it may return in any other part of the body, such as the bones, liver, lungs, or brain.
