Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis. There are different stage descriptions for different types of cancer.
One tool that doctors use to describe the stage is the TNM system. This system uses three criteria to judge the stage of the cancer: the size of the tumor itself, the presence of cancer in the lymph nodes around the tumor, and whether the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero), which is non-invasive ductal carcinoma in situ (DCIS), and stages I through IV (one through four), which represent invasive breast cancer. The stage provides a common way of describing the cancer so doctors can work together to plan the best treatments.
TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:
- How large is the primary tumor and where is it located? (Tumor, T)
- Has the tumor spread to the lymph nodes? (Node, N)
- Has the cancer metastasized to other parts of the body? (Metastasis, M)
There are two types of staging for breast cancer. First, the clinical stage is based on the results of tests done before surgery, such as a physical examination, x-rays, CT scans, and MRI tests. Then, the pathologic stage is assigned based on information found during surgery, plus the laboratory results (pathology) of the breast tissue and any lymph nodes removed during surgery. In general, more importance is placed on the pathologic stage than the clinical stage.
Cancer stage grouping
Doctors assign the stage of the cancer by combining the T, N, and M classifications (read about specific T, N, and M classifications in the Guide to Breast Cancer.) Inflammatory breast cancer is generally considered stage IIIB breast cancer at a minimum at the time of diagnosis.
Stage 0: Stage zero (0) describes disease that is confined within the ducts and lobules of the breast tissue and has not spread into the surrounding tissue of the breast. It is also called noninvasive cancer (Tis, N0, M0).
Stage IA: The tumor is small, invasive, and has not spread to the lymph nodes (T1, N0, M0).
Stage IB: The tumor is confined within the ducts and lobules of the breast tissue and has not spread into the surrounding tissue of the breast, or it is smaller than 20 mm, with microscopic spread to the lymph nodes (T0 or T1, N1mic, M0).
Stage IIA: Any one of these conditions:
- There is no evidence of a tumor in the breast, but the cancer has spread to the axillary lymph nodes but not to distant areas of the body. (T0, N1, M0).
- The tumor is 20 mm or smaller and has spread to the axillary lymph nodes (T1, N1, M0).
- The tumor is larger than 20 mm but not larger than 50 mm and has not spread to the axillary lymph nodes (T2, N0, M0).
Stage IIB: Any one of these conditions:
- The tumor is larger than 20 mm but not larger than 50 mm and has spread to one to three axillary lymph nodes (T2, N1, M0).
- The tumor is larger than 50 mm but has not spread to the axillary lymph nodes (T3, N0, M0).
Stage IIIA: This stage describes a cancer of any size that has spread to four to nine axillary lymph nodes, but not to other parts of the body (T0, T1, T2 or T3, N2, M0). Stage IIA may also be a tumor larger than 50 mm that has spread to one to three lymph nodes (T3, N1, M0).
Stage IIIB: The tumor has spread to the chest wall or caused swelling or ulceration of the breast or is diagnosed as inflammatory breast cancer. It may or may not have spread to the lymph nodes under the arm, but it has not spread to other parts of the body (T4; N0, N1 or N2; M0).
Stage IIIC: A tumor of any size that has not spread to distant parts of the body but has spread to 10 or more axillary lymph nodes or the lymph nodes in the N3 group (any T, N3, M0).
Stage IV (metastatic): The tumor can be any size and has spread to distant sites in the body, usually the bones, lungs or liver, or chest wall (any T, any N, M1). Metastatic cancer spread is found at the time of breast cancer diagnosis about 5% to 6% of the time. Most commonly, metastatic breast cancer is the result of a recurrence many months to years following the original cancer diagnosis and treatment.
Recurrent: Recurrent cancer is cancer that comes back after treatment.
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual Seventh Edition (2010) published by Springer-Verlag New York, www.cancerstaging.net.