Breast Cancer Staging

If the biopsy shows that you have breast cancer, your doctor needs to learn the disease’s extent (stage) to choose the best breast cancer treatment options for you. The stage of your breast cancer is based on: 

  • the size of the tumor
  • whether cancer has spread to nearby tissue
  • whether the cancer has spread to other parts of the body

Tests Used for Staging Breast Cancer

The information gained from the staging process will help your cancer care team provide customized cancer care for each patient’s specific needs. Staging may involve using some of the same test results gathered during the diagnostic process, in addition to other tests. These tests will also show if the breast cancer has spread and, if so, to what parts of your body.

Sentinel Lymph Node Biopsy

One test, a sentinel lymph node biopsy, happens after surgery when nearby lymph nodes are collected and examined to see if cancer cells are present. The stage is typically unknown until after surgery to remove the tumor in your breast, along with one or more lymph nodes under your arm. 

Breast cancer surgeons remove the lymph nodes that are most likely to have breast cancer cells. A blue dye, a radioactive substance, or both are injected near the breast tumor or under the nipple. Then, the surgeon uses a scanner to find the sentinel lymph node(s) containing the radioactive material or looks for the lymph node stained with the blue dye. These sentinel nodes are removed and checked for cancer cells. When breast cancer spreads, the cancer cells are often found in the axillary lymph nodes in the armpit. 

Additional tests used for breast cancer staging may involve:

  • Blood Tests
  • Bone Scan
  • CT or PET Scans
  • Chest X-Ray

When Breast Cancer Spreads

Breast cancer can spread to almost any other part of the body, such as the bones, liver, lungs, and brain. When breast cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary (original) cancer tumor. 

For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer. For that reason, it is treated as breast cancer, not bone cancer. Doctors call the new tumor “distant” or metastatic breast cancer.

Stages of Breast Cancer

The stage of breast cancer is based on several factors:

  1. The location and size of the primary tumor
  2. If the cancer has spread to nearby lymph nodes or other areas of the body
  3. Tumor grade
  4. The presence of certain biomarkers.

Breast Cancer Staging TNM System

The location, size of the tumor and if the cancer has spread to the lymph nodes are noted 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: Tumor Size Categories for Breast Cancer

T followed by a number from 0 to 4 describes the primary tumor’s size and its spread to the skin or the chest wall under the breast. Higher T numbers mean a larger tumor 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 four subtypes of a T1 tumor, depending on the size of the tumor:
    • T1mi: the cancer 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 cancer has grown into the chest wall 
    • T4b: the cancer 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, or there is swelling of the skin on the breast.
    • T4c: the cancer 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: Lymph Node Status for Breast Cancer

N followed by a number from 0 to 3 indicates whether 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 imaging tests found the cancer. 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 imaging tests found the cancer;
      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.

M: Metastases Categories for Breast Cancer

  • 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.

Breast Cancer Stage Grouping

The following grouping by T, N, and M, according to the stage, is provided by the American Society of Clinical Oncology.

Stage 0

Also called non-invasive. Disease that is only in the ducts of the breast tissue and has not spread to the surrounding tissue of the breast. 

Tis

Ta

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

T1 or T2

N1

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. 

  • The tumor is 20 mm or smaller and has spread to the axillary lymph nodes.

  • The tumor is larger than 20 mm but not larger than 50 mm and has not spread to the axillary lymph nodes.



 

T0



 

T1

 

T2



 

N1



 

N1

 

N0



 

M0



 

M0

 

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.

  • The tumor is larger than 50 mm but has not spread to the axillary lymph nodes.



 

T2

 

T3



 

N1

 

N0



 

M0

 

M0

Stage IIIA

Either of these conditions:

  • 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 

  • A tumor larger than 50 mm that has spread to 1 to 3 axillary lymph nodes

 

T0, T1, T2 or T3

  T3
 

N2



 

N1

 

M0



 

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 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

Also called metastatic breast cancer. 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

Recurrent

Recurrent breast cancer is cancer that has come back after a time when it could not be detected following treatment. Even when the cancer seems to be 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 return in any other part of the body, such as the bones, liver, lungs, or brain. 

The recurrent breast cancer may be described as local, regional, or distant.

 

Breast Cancer Tumor Grade

The tumor’s grade is a measurement of how much the cancer cells look like healthy cells. Tumor grading will give the oncologist a better idea of how quickly the cancer is likely to grow and spread.

To describe how abnormal the cancer cells and tissue are, the pathologist will assess the following three features:

  1. The amount of ordinary (non-cancerous) breast ducts in the tumor tissue.
  2. The size and shape of the breast cancer tumor cells.
  3. How fast the tumor cells are or are not growing and dividing.

For each feature, the pathologist assigns a score of 1 to 3; a score of “1” means the cells and tumor tissue look the most like healthy cells and tissue, and a score of “3” means the cells and tissue look the most abnormal. The scores for each feature are added together to get a total score between 3 and 9.

Three grades of breast cancer are possible:

  • A total score between 3 to 5: G1 (Low grade or well-differentiated).
  • A total score between 6 to 7: G2 (Intermediate grade or moderately differentiated).
  • A total score between 8 to 9: G3 (High grade or poorly differentiated).

The grade is determined after a biopsy.