Breast Cancer

All Types of Cancer

Breast Cancer Staging

After a breast cancer diagnosis, the oncologist will need to determine if cancer cells have spread outside of the breast. Staging can sometimes take a little while to determine because results need to be gathered from different types of tests. One of these tests may be available after surgery when nearby lymph nodes are examined to see if cancer cells have spread there.

In breast cancer, stage is based on several factors:

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

TNM System

The TNM staging system is a classification system developed by the American Joint Committee on Cancer for describing the extent of disease progression in cancer patients.

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 categories for breast cancer

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: The primary tumor cannot be assessed
  • T0: There is 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 (mm) or less. There are 4 subtypes of a T1 tumor depending on the size of the tumor:
    • T1mi: tumor is 1 mm or less.
    • T1a: tumor is greater than 1 mm but not greater than 5 mm.
    • T1b: tumor is greater than 5 mm but not greater than 10 mm.
    • T1c: tumor is greater than 10 mm but not greater than 20 mm.
  • T2: Tumor is greater than 20 mm but not greater than 50 mm.
  • T3: Tumor is greater than 50 mm.
  • T4: Tumor is described as one of the following:
    • T4a: tumor has grown into the chest wall
    • T4b: 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: 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 categories for breast cancer

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: Lymph nodes cannot be assessed.
  • N0: There is no sign of cancer in the lymph nodes, or tiny clusters of cancer cells not greater than 0.2 millimeters (mm) in the lymph nodes
  • N1: The cancer is described as one of the following:
    • N1mi: the cancer has spread to the axillary (armpit area) lymph nodes and is greater than 0.2 mm but not greater than 2 mm.
    • N1a: the cancer has spread to 1 to 3 axillary lymph nodes and the cancer in at least one of the lymph nodes is greater than 2 mm.
    • N1b: the cancer has spread to lymph nodes near the breastbone on the same side of the body as the primary tumor, and the cancer is greater than 0.2 mm and is found by sentinel lymph node biopsy. Cancer is not found in the axillary lymph nodes.
    • N1c: the cancer has spread to 1 to 3 axillary lymph nodes and the cancer in at least one of the lymph nodes is greater than 2 mm. 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: The cancer is described as one of the following:
    • N2a: the cancer has spread to 4 to 9 axillary lymph nodes and the cancer in at least one of the lymph nodes is greater than 2 mm.
    • N2b: the 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: The cancer is described as one of the following:
    • N3a: the 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 mm, or cancer has spread to lymph nodes below the collarbone.
    • N3b: the 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 mm. Cancer has also spread to lymph nodes near the breastbone and the cancer is found by imaging tests;

OR

  • the cancer has spread to 4 to 9 axillary lymph nodes and cancer in at least one of the lymph nodes is larger than 2 mm. 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 mm and is found by sentinel lymph node biopsy.
  • N3c: the cancer has spread to lymph nodes above the collarbone on the same side of the body as the primary tumor.

M categories for breast cancer

  • M0: There is no sign that cancer has spread to other parts of the body.
  • M1: The 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 greater than 0.2 mm. The cancer is called metastatic breast cancer.

Breast Cancer Stage Grouping

The following grouping by T, N, and M according to 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 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.

Breast Cancer Tumor Grade

Grade refers to how different the cancer cells look from healthy cells, and whether they appear slower-growing or faster-growing. If the cancer looks similar to healthy tissue and has different cell groupings, it is called "well-differentiated" or a "low-grade tumor." If the cancerous tissue looks very different from healthy tissue, it is called "poorly differentiated" or a "high-grade tumor."

There are three grades:

  • Grade 1 (well-differentiated): total score of 3 to 5
  • Grade 2 (moderately differentiated): total score of 6 to 7
  • Grade 3 (poorly differentiated): total score of 8 to 9

Biomarkers

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.

The results of the testing will produce a positive (+) or negative (-) for each biomarker as part of the diagnosis. For some patients there are no biomarkers present. This will be classified as triple-negative breast cancer.

Learn more about hormone receptors in breast cancer.