After a breast cancer diagnosis, the oncologist will need to determine the extent (stage) of the disease in order to prepare the best treatment plan. This process can sometimes take a little while since results need to be gathered from different types of tests. One of these tests may be completed after surgery from lymph nodes examined during surgery if indicated to see if cancer cells were present.
In breast cancer, stage is based on several factors:
The size and location of the primary tumor
The spread of cancer to nearby lymph nodes or other parts of the body
Tumor grade
The presence of certain biomarkers
The first two items on the list are determined using the TNM system. TNM stands for:
T = Tumor size
N = Lymph Node status (the number and location of lymph nodes with cancer)
M = Metastases (whether or not the cancer has spread to other parts of the body)
T followed by a number from 0 to 4 describes the main (primary) tumor's size and if it has spread to the skin or to the chest wall under the breast. Higher T numbers mean a larger tumor and/or wider spread to tissues near the breast.
TX: Primary tumor cannot be assessed
T0: No sign of primary tumor
Tis: Carcinoma in situ (DCIS, or Paget disease of the breast with no associated tumor mass)
T1: The tumor is 20 millimeters or smaller. There are 4 subtypes of a T1 tumor
depending on the size of the tumor:T1mi: the tumor is 1 millimeter or smaller.
T1a: the tumor is larger than 1 millimeter but not larger than 5 millimeters.
T1b: the tumor is larger than 5 millimeters but not larger than 10 millimeters.
T1c: the tumor is larger than 10 millimeters but not larger than 20 millimeters.
T2: The tumor is larger than 20 millimeters but not larger than 50 millimeters.
T3: The tumor is larger than 50 millimeters.
T4: The tumor is described as one of the following:
T4a: the tumor has grown into the chest wall
T4b: the tumor has grown into the skin—an ulcer has formed on the surface of the skin on the breast, small tumor nodules have formed in the same breast as the primary tumor, and/or there is swelling of the skin on the breast.
T4c: the tumor has grown into the chest wall and the skin.
T4d: inflammatory breast cancer—one-third or more of the skin on the breast is red and swollen (called peau d’orange).
N followed by a number from 0 to 3 indicates whether the cancer has spread to lymph nodes near the breast and, if so, how many lymph nodes are involved.
NX: The lymph nodes cannot be assessed.
N0: No sign of cancer in the lymph nodes, or tiny clusters of cancer cells not larger than 0.2 millimeters in the lymph nodes
N1: Cancer is described as one of the following:
N1mi: cancer has spread to the axillary (armpit area) lymph nodes and is larger than 0.2 millimeters but not larger than 2 millimeters.
N1a: cancer has spread to 1 to 3 axillary lymph nodes and the cancer in at least one of the lymph nodes is larger than 2 millimeters.
N1b: cancer has spread to lymph nodes near the breastbone on the same side of the body as the primary tumor, and the cancer is larger than 0.2 millimeters and is found by sentinel lymph node biopsy. Cancer is not found in the axillary lymph nodes.
N1c: cancer has spread to 1 to 3 axillary lymph nodes and the cancer in at least one of the lymph nodes is larger than 2 millimeters. Cancer is also found by sentinel lymph node biopsy in the lymph nodes near the breastbone on the same side of the body as the primary tumor.
N2: Cancer is described as one of the following:
N2a: cancer has spread to 4 to 9 axillary lymph nodes and the cancer in at least one of the lymph nodes is larger than 2 millimeters.
N2b: cancer has spread to lymph nodes near the breastbone and the cancer is found by imaging tests. Cancer is not found in the axillary lymph nodes by sentinel lymph node biopsy or lymph node dissection.
N3: Cancer is described as one of the following:
N3a: cancer has spread to 10 or more axillary lymph nodes and the cancer in at least one of the lymph nodes is larger than 2 millimeters, or cancer has spread to lymph nodes below the collarbone.
N3b: cancer has spread to 1 to 9 axillary lymph nodes and the cancer in at least one of the lymph nodes is larger than 2 millimeters. Cancer has also spread to lymph nodes near the breastbone and the cancer is found by imaging tests;
OR
cancer has spread to 4 to 9 axillary lymph nodes and cancer in at least one of the lymph nodes is larger than 2 millimeters. Cancer has also spread to lymph nodes near the breastbone on the same side of the body as the primary tumor, and the cancer is larger than 0.2 millimeters and is found by sentinel lymph node biopsy.
N3c: cancer has spread to lymph nodes above the collarbone on the same side of the body as the primary tumor.
M0: There is no sign that cancer has spread to other parts of the body.
M1: Cancer has spread to other parts of the body, most often the bones, lungs, liver, or brain. If cancer has spread to distant lymph nodes, the cancer in the lymph nodes is larger than 0.2 millimeters. The cancer is called metastatic breast cancer.
The following grouping by T, N and M according to stage is provided by the American Society of Clinical Oncology.
Stage 0: Stage zero (0) describes disease that is only in the ducts of the breast tissue and has not spread to the surrounding tissue of the breast. It is also called non-invasive or in situ 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 to the lymph nodes and the cancer in the lymph node 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 1 to 3 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 1 to 3 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. 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 spread to 1 to 3 axillary lymph nodes (T3, N1, M0).
Stage IIIB: The tumor has spread to the chest wall or caused swelling or ulceration of the breast, or it is diagnosed as inflammatory breast cancer. It may or may not have spread to up to 9 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 found when the cancer is first diagnosed occurs about 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 and can be described as local, regional, and/or distant. 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.
The grading system describes a tumor based on how abnormal the cancer cells and tissue look under a microscope and how quickly the cancer cells are likely to grow and spread. Low-grade cancer cells look more like normal cells and tend to grow and spread more slowly than high-grade cancer cells. To describe how abnormal the cancer cells and tissue are, the pathologist will assess the following three features:
How much of the tumor tissue has normal breast ducts.
The size and shape of the nuclei in the tumor cells.
How many dividing cells are present, which is a measure of how fast the tumor cells are growing and dividing.
For each feature, the pathologist assigns a score of 1 to 3:
Grade 1: Cancer cells and tumor tissue look the most like normal cells and tissue, and they grow in slow, well-organized patterns. Not that many cells are dividing to make new cancer cells.
Grade 2: Cancer cells do not look like normal cells and are growing and dividing a little faster than normal.
Grade 3: Cancer cells look very different from normal cells. They grow quickly in disorganized, irregular patterns, with many dividing to make new cancer cells.
The scores for each feature are added together to get a total score between 3 and 9:
Total score of 3 to 5: G1 (Low grade or well-differentiated)
Total score of 6 to 7: G2 (Intermediate grade or moderately differentiated)
Total score of 8 to 9: G3 (High grade or poorly differentiated)
Prognosis is poorer with a higher tumor grade for any given tumor size and breast cancer stage.
Healthy breast cells, and some breast cancer cells, have receptors (biomarkers) that attach to the hormones estrogen and progesterone. These hormones are needed for healthy cells, and some breast cancer cells, to grow and divide. To check for these biomarkers, samples of tissue containing breast cancer cells are removed during a biopsy or surgery. The samples are tested in a laboratory to see whether the breast cancer cells have estrogen, progesterone, or HER2 receptors.
For breast cancer, biomarker testing includes the following:
Estrogen receptor (ER). If the breast cancer cells have estrogen receptors, the cancer cells are called ER positive (ER+). If the breast cancer cells do not have estrogen receptors, the cancer cells are called ER negative (ER-).
Progesterone receptor (PR). If the breast cancer cells have progesterone receptors, the cancer cells are called PR positive (PR+). If the breast cancer cells do not have progesterone receptors, the cancer cells are called PR negative (PR-).
Human epidermal growth factor type 2 receptor (HER2/neu or HER2). If the breast cancer cells have larger than normal amounts of HER2 receptors on their surface, the cancer cells are called HER2 positive (HER2+). If the breast cancer cells have a normal amount of HER2 on their surface, the cancer cells are called HER2 negative (HER2-). HER2+ breast cancer is more likely to grow and divide faster than HER2- breast cancer.
Sometimes the breast cancer cells will be described as triple negative or triple positive.
Triple negative. If the breast cancer cells do not have estrogen receptors, progesterone receptors, or a larger than normal amount of HER2 receptors, the cancer cells are called triple negative.
Triple positive. If the breast cancer cells do have estrogen receptors, progesterone receptors, and a larger than normal amount of HER2 receptors, the cancer cells are called triple positive.
Knowing the estrogen receptor, progesterone receptor, and HER2 receptor status is very important when it comes to choosing the best breast cancer treatment. Talk to your oncologist to find out what your breast cancer stage is and how it influences their treatment recommendation for you.
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