ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread. This is called the stage. Use the menu to see other pages.
Staging is a way of describing where the cancer is located, how much the cancer has grown, and if or where it has spread. Doctors use diagnostic tests to find out 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, which is the chance of recovery. There are different stage descriptions for different types of cancer.
TNM staging system
The most commonly used tool that doctors use to describe the stage is the TNM system. Doctors use the results from diagnostic tests and scans to answer these questions:
Tumor (T): How large is the primary tumor? Where is it located?
Node (N): Has the tumor spread to the lymph nodes? If so, where and how many?
Metastasis (M): Has the cancer metastasized to other parts of the body? If so, where and how much?
The results are combined to determine the stage of cancer for each person. There are 5 stages: stage 0 (zero), which is noninvasive ductal carcinoma in situ (DCIS), and stages I through IV (1 through 4), which are used for invasive breast cancer. The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
There are 2 types of TNM staging for breast cancer. First, the clinical stage is based on the results of tests done before surgery, which may include a physical examination, mammogram, ultrasound, and MRI scans. Then, the pathologic stage is assigned based on the pathology results from the breast tissue and any lymph nodes removed during surgery. It is usually determined several days after 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. They also use other factors, such as tumor grade and the results of ER/PR and HER2 testing to determine the stage and your prognosis (see Diagnosis).
Inflammatory breast cancer is generally considered stage IIIB breast cancer when it is first diagnosed. It may be diagnosed as stage IV if it has spread outside the breast and lymph nodes.
Stage 0: Stage zero (0) describes disease that is only in the ducts and lobules of the breast tissue and has not spread to 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: Cancer has spread only to the lymph nodes and is larger than 0.2 mm but less than 2 mm in size. There is either no evidence of a tumor in the breast or the tumor in the breast is 20 mm or smaller (T0 or T1, N1mi, M0).
Stage IIA: Any 1 of these conditions:
There is no evidence of a tumor in the breast, but the cancer has spread to the lymph nodes under the arm called the axillary lymph nodes. It has not spread to distant parts 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: Either of these conditions:
The tumor is larger than 20 mm but not larger than 50 mm and has spread to 1 to 3 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: The cancer of any size has spread to 4 to 9 axillary lymph nodes or to internal mammary lymph nodes, which are located under the sternum or breastbone. It has not spread to other parts of the body (T0, T1, T2 or T3, N2, M0). Stage IIIA may also be a tumor larger than 50 mm that has small areas of cancer in the 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 axillary or internal mammary lymph nodes. 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 spread to 10 or more axillary lymph nodes, the internal mammary lymph nodes, and/or the lymph nodes under the collarbone. It has not spread to other parts of the body (any T, N3, M0).
Stage IV (metastatic): The tumor can be any size and has spread to other organs, such as the bones, lungs, brain, liver, distant lymph nodes, or chest wall (any T, any N, M1). Metastatic cancer spread found when the cancer is first diagnosed occurs about 5% to 6% of the time. This may be called de novo metastatic breast cancer. Most commonly, metastatic breast cancer is found after a previous diagnosis of early breast cancer. Learn more about metastatic breast cancer.
Recurrent: Recurrent cancer is cancer that has come back after treatment. A breast cancer recurrence can be either local or distant or both. If the cancer does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.
Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer International Publishing.
Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Treatment Options. You may use the menu to choose a different section to read in this guide.