After breast cancer is diagnosed, tests are performed to find out if the cancer has spread within the breast or has spread to other parts of the body.
The process used to find out if the cancer has spread in the breast or has spread to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage of the cancer in order to plan treatment. Some of the tests used to diagnose breast cancer are also used for staging. (See the “General Information” section.)
The following tests and methods can also be used in the staging process:
Sentinel lymph node biopsy: Intraoperative removal of the sentinel lymph nodes. The sentinel lymph node is the first lymph node in a group of lymph nodes to receive lymphatic drainage from the primary tumor. It is the first station lymph node to which the cancer may spread from the primary tumor. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymphatic vessels to the lymph node. The first lymph node that receives the substance or dye is removed. The pathologist looks at the tissue under a microscope to look for cancer cells. If no cancer cells are found, it may not be necessary to remove more lymph nodes. Sometimes, anterior lymph nodes are found in more than one group of lymph nodes.
X-ray chest x-ray: An x-ray of the organs and bones inside the chest. x-rays are a type of energy beam that penetrates and images the body, ending up with a picture of what is going on in various areas of the body.
CT scan (CAT scan): A method of taking a series of detailed images of the internal areas of the body from different angles by connecting a computer to an x-ray machine. Dye may be injected into a vein or swallowed to improve the clarity of the organs or tissues shown, also known as computed tomography, computed tomography, or computerized axial level radiography.
Bone scan: A method to check for the presence of rapidly dividing cells (such as cancer cells) in the bones. A very small amount of radioactive material is injected into a vein and moves with the bloodstream. The radioactive material collects in the bones with cancer and is detected by the scanner.
PET scan (positron emission tomography): A method to detect malignant cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. the PET scanner rotates around the body and takes pictures of where the glucose is located in the body. Malignant tumor cells are more active than normal cells and take up more glucose, so they appear brighter in the picture.
Cancer spreads through the body in three ways.
Cancer can spread through the tissues, the lymphatic system, and the blood:
Tissues. Cancer grows and spreads from its origin to the surrounding area.
Lymphatic system. Cancer spreads from its origin by invading the lymphatic system and reaches other parts of the body through the lymphatic vessels.
Blood. Cancer spreads from its origin by invading the blood and reaches other parts of the body through blood vessels.
Cancer can spread from its origin to other parts of the body.
When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from their origin (the primary cancer) and move through the lymphatic system or bloodstream.
Lymphatic system. The cancer invades the lymphatic system, moves through the lymphatic vessels, and forms a tumor in another part of the body (metastatic cancer).
Blood. The cancer invades the bloodstream, moves through blood vessels, and forms a tumor in another part of the body (metastatic cancer).
Metastases and primary tumors are the same type of cancer. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. This disease is metastatic breast cancer, not bone cancer.
Many cancer deaths are caused by the cancer metastasizing from the initial tumor to other tissues and organs. This is called metastatic cancer. The following animation demonstrates the way cancer cells metastasize from their origin to other parts of the body.
In breast cancer, staging depends on the size and location of the primary tumor, the spread of cancer cells to adjacent lymph nodes or other parts of the body, the tumor grade, and the presence or absence of certain biomarkers.
To plan the best treatment and to understand your prognosis, it is important to know the stage of breast cancer.
Breast cancer is divided into 3 types:
First, clinical prognostic stage is divided into stages for all patients based on history, physical examination, imaging (if completed), and biopsy. Clinical prognostic stage is described by the TNM system, tumor grade, and biomarker status (ER, PR, HER2). In clinical staging, the lymph nodes are examined for signs of cancer using mammography or ultrasound.
Pathologic prognostic staging is then used for patients undergoing their first surgical treatment. Pathologic prognostic staging is based on all clinical information, biomarker status, and laboratory testing of breast tissue and lymph nodes removed during surgery.
Anatomic staging is based on the size and spread of the cancer as described by the TNM system. Anatomic staging is used in areas where biomarker testing is lacking. It is not used in the United States.
The TNM system is used to describe the size of the primary tumor and the spread of the tumor to adjacent lymph nodes or other parts of the body.
For breast cancer, the TNM system describes the tumor as follows:
Tumor (T) size and location of tumor
Tumor size is usually measured in millimeters or centimeters. Common items that can be expressed in mm for tumor size include: sharp pencil tips (1 mm), new crayon tips (2 mm), pencil-style erasers (5 mm), peas (10 mm), peanuts (20 mm), and limestone (50 mm).
TX: Primary tumor could not be evaluated.
T0: No signs of primary tumor in the breast.
Tis: carcinoma in situ. There are two types of in situ breast cancer.
Tis (DCIS):DCIS is a disease in which abnormal cells occur in the lining of the ducts of the breast. These abnormal cells have not spread to other tissues outside the breast ducts. In some cases, DCIS may become invasive breast cancer and can spread to other tissues. At this time, there is no way to know which lesions will become invasive.
Tis (Paget’s disease): Paget’s disease is a condition in which abnormal cells are found in the skin cells of the nipple and may spread to the areola. Its not staged according to the TNM system. The TNM system is used to stage invasive breast cancer if Paget’s disease and invasive breast cancer are present.
T1: Tumor less than or equal to 20 mm. there are four subtypes of T1 tumors depending on the size of the tumor.
T1mi: tumor less than or equal to 1 mm.
T1a: tumor greater than 1 mm but less than or equal to 5 mm.
Tumor greater than 5 mm but less than or equal to 10 mm.
Tumor greater than 10 mm but less than or equal to 20 mm.
T2: Tumor greater than 20 mm but less than or equal to 50 mm.
T3: Tumor greater than 50 mm.
T4: Tumor described as follows.
T4a: The tumor has grown into the chest wall.
T4b: The tumor has grown into the skin, formed an ulcer on the skin surface of the breast, formed a small tumor in the same breast as the primary tumor, and/or the skin of the breast has swollen.
T4c: Tumor has grown into the chest wall and skin.
T4d: The skin of the upper third or more of the breast in inflammatory breast cancer is red and swollen (called orange peel changes).
Lymph nodes (N). The size and location of the lymph nodes where the cancer has spread.
Pathologic staging is used to describe lymph nodes when they are surgically removed and studied by a pathologist under a microscope. The pathologic staging of lymph nodes is described below.
NX: Lymph nodes cannot be evaluated.
N0: There is no sign of cancer in the lymph node or a tiny mass of cancer cells no larger than 0.2 mm in the lymph node.
N1: One of the following is present.
N1mi: Cancer cells that have spread to the axillary lymph nodes and are greater than 0.2 mm but less than or equal to 2 mm.
N1a: Cancer cells have spread to 1 to 3 axillary lymph nodes, at least one of which has cancer cells larger than 2 mm.
N1b: The cancer has spread to lymph nodes near the sternum on the same side as the primary tumor, and the cancer is greater than 0.2 mm and has been detected by biopsy of the anterior lymph nodes. No cancer was found in the axillary lymph nodes.
N1c: The cancer has spread to one to three axillary lymph nodes, at least one of which has cancer greater than 2 mm. Lymph nodes located near the sternum on the same side as the primary tumor were also found to have cancer in the anterior lymph node biopsy.
N2: Cancer was described as one of the following.
N2a: Cancer has spread to 4 to 9 axillary lymph nodes, at least one of which has cancer cells larger than 2 mm.
N2b: The cancer has spread to lymph nodes near the sternum, and the cancer is detected by imaging. No cancer in the axillary lymph nodes was detected by either biopsy of the anterior lymph nodes or lymph node dissection.
N3: Cancer is described as one of the following.
N3a: Cancer has spread to 10 or more axillary lymph nodes, with cancer greater than 2 mm in at least one lymph node, or cancer has spread to the subclavian lymph nodes.
N3b: Cancer has spread to 1 to 9 axillary lymph nodes, including at least one lymph node with cancer cells greater than 2 mm. Cancer cells have also spread to lymph nodes near the sternum, where cancer cells are detected by imaging.
Or
the cancer has spread to 4 to 9 axillary lymph nodes, at least one of which is larger than 2 mm. The cancer has also spread to lymph nodes near the sternum on the same side as the primary tumor, the cancer is greater than 0.2 mm, and it is detected by biopsy of the anterior lymph node.
N3c: The cancer has spread to a lymph node above the clavicle on the same side as the primary tumor.
Clinical staging is generated when lymph nodes are examined using mammography or ultrasound. The clinical staging of lymph nodes is not described here.
Metastasis (M). The cancer has spread to other parts of the body.
M0: There is no indication that the cancer has spread to other parts of the body.
M1: The cancer has spread to other parts of the body, usually the bones, lungs, liver, or brain. If the cancer has spread to distant lymph nodes, then the cancer cells in the lymph nodes are larger than 0.2 mm. This type of cancer is called metastatic breast cancer.
The grading system is used to describe the rate at which breast tumors grow and spread.
The grading system describes tumors based on the abnormal appearance of cancer cells and tissue under the microscope and the rate at which the cancer cells may 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 the abnormalities of cancer cells and tissue, the pathologist will evaluate the following three features:
How much of the tumor tissue contains normal breast ducts.
The size and shape of the nucleus in the tumor cells.
How many dividing cells are present, which is a measure of the rate of tumor cell growth and division.
For each feature, the pathologist scores it on a scale of 1 to 3; a score of “1” means that the cells and tumor tissue look most like normal cells and tissue, and a score of “3” means that the cells and tissue look most abnormal. The scores for each feature were summed to give a total score between 3 and 9.
There are three possible grades:
Total score of 3-5: G1 (low grade or highly differentiated).
Total score of 6-7: G2 (medium level or medium differentiation).
Total score 8-9: G3 (high-grade or poorly differentiated).
Biomarker testing is used to determine if breast cancer cells have certain receptors.
Healthy breast cells, and some breast cancer cells, have attached estrogen and progesterone receptors (biomarkers). These hormones are necessary for the growth and division of healthy cells and some breast cancer cells. To check for these biomarkers, a sample of tissue containing breast cancer cells is removed during a biopsy or surgery. These samples are tested in the laboratory to determine if the breast cancer cells have estrogen or progesterone receptors.
Another receptor (biomarker) called HER2 is found on the surface of all breast cancer cells. HER2 receptors are required for breast cancer cell growth and division.
For breast cancer, biomarker testing includes the following:
Estrogen receptor (ER). If breast cancer cells have estrogen receptors, the cancer cells are said to be ER-positive (ER+). If the breast cancer cells do not have estrogen receptors, the cancer cells are said to be ER-negative (ER-).
Progesterone receptor (PR). If the breast cancer cells have progesterone receptors, the cancer cells are said to be PR-positive (PR+). If the breast cancer cells do not have progesterone receptors, the cancer cells are said to be PR-negative (PR-).
Human epidermal growth factor type 2 receptor (HER2/neu or HER2). If breast cancer cells have a greater than normal number of HER2 receptors on their surface, they are said to be HER2-positive (HER2+). If there is a normal amount of HER2 on the surface of the breast cancer cells, the cancer is called HER2 negative (HER2-). HER2+ breast cancers grow and divide more rapidly than HER2- breast cancers.
Sometimes breast cancer cells are described as triple-negative or triple-positive.
Triple-negative. If the breast cancer cells are estrogen receptor negative, progesterone receptor negative, and HER2 receptor negative, the cancer cells are said to be triple negative.
Triple-positive. If the breast cancer cells do have estrogen receptors, progesterone receptors, and greater than normal amounts of HER2 receptors, the cancer cells are said to be triple positive.
It is important to know the status of the estrogen receptor, progesterone receptor, and HER2 receptor to choose the best treatment. There are drugs that can block the receptors from attaching to the hormone estrogen and progesterone receptors and stop the cancer from progressing. Other drugs can be used to block HER2 receptors on the surface of breast cancer cells and stop the cancer from progressing.
The combination of the TNM system, grading system, and biomarker status can determine the stage of breast cancer.
The following are three examples of combining the TNM system, grading system, and biomarker status to determine the pathologic prognostic stage of breast cancer in women whose first treatment was surgery:
If the tumor is 30 mm in size (T2), has not spread to nearby lymph nodes (N0), has not spread to distant parts of the body (M0), and is:
Grade 1
HER2+
ER-
PR-
The cancer is stage IIA.
If the tumor is 53 mm in size (T3), has spread to 4 to 9 axillary lymph nodes (N2), has not spread to other parts of the body (M0), and is:
Grade 2
HER2+
ER+
PR-
The tumor is stage IIIA.
If the tumor is 65 mm in size (T3), has spread to 3 axillary lymph nodes (N1a), has spread to the lung (M1), and is:
Grade 1
HER2+
ER-
PR-
The cancer is stage IV (metastatic breast cancer).
Consult your doctor to find out what stage your breast cancer is and how to use it to plan the best treatment plan for you.
After surgery, your doctor will receive a pathology report describing the size and location of the primary tumor, the spread of cancer cells to nearby lymph nodes, the tumor grade, and the presence of certain biomarkers. The pathology report and other test results are used to determine the stage of breast cancer.
You may have many questions. Ask your doctor to explain how staging determines the best choice for treating your cancer and whether there is a clinical trial that is right for you.
The treatment of breast cancer depends to some extent on the stage of the disease.
For ductal carcinoma in situ (DCIS) treatment options, see ductal carcinoma in situ.
For treatment options for stage I, stage II, stage IIIA, and operable stage IIIC breast cancer, see Early-stage, localized, or operable breast cancer.
For treatment options for stage IIIB, inoperable stage IIIC, and inflammatory breast cancer, see Locally advanced or inflammatory breast cancer.
For treatment options for cancers that recur near their initial area of formation, see Locally recurrent breast cancer.
For treatment options for stage IV (metastatic) breast cancer or breast cancer that has recurred elsewhere in the body, see metastatic breast cancer.