Triple Negative Breast Cancer


Once breast cancer is diagnosed, the disease must be staged according to the extent of cancer, including how much is in the body, where it’s located, and whether or how far it has metastasized (spread). Staging helps the doctor plan a course of treatment.

Clinical staging, which is done by the managing physician, is based on the tumor’s characteristics as assessed through a physical exam, X-rays, scans and/or other imaging studies and laboratory results. Pathologic staging is done by a pathologist, who examines tissue specimens removed during surgery or biopsy.

The staging system used for most cancers, called TNM staging, was developed by the American Joint Committee on Cancer (AJCC). This tumor (T), node (N) and metastasis (M) classification (see Table 1) is then used as the foundation for the overall stage of breast cancer.

The T (tumor) classification is the same for both clinical and pathologic staging. This category provides information on the size and extent of the tumor within the breast. Clinical staging for the N (node) category describes which lymph nodes have evidence of breast cancer cells. The anatomic location of the involved lymph nodes is important because it shows the extent the disease has spread. The pathologic N (node) category (sometimes denoted as pN) shows how many lymph nodes are involved and the amount of tumor cells actually found in the nodes.

The M (metastasis) category indicates whether there’s evidence of distant metastasis (spread of cancer to another part of the body beyond the breast and local lymph nodes). Staging for the M category is primarily clinical, although a new M subcategory is based on the presence of tumor cells that can be detected only by microscopic examination or with molecular testing. The most common sites of distant metastasis in breast cancer are the bones, lungs, liver and brain.

After the breast cancer has been classified according to this system, an overall stage is assigned (see Table 2).

A pathologist will also assign a grade to your breast cancer, which is based on the microscopic features of tumor cell growth rate and aggressiveness. Knowing the grade helps determine how fast a cancer is likely to grow and how likely it is to spread. Triple-negative breast cancers are often diagnosed as Grade 3, meaning they tend to grow quickly and spread. Higher grade cancers may be more aggressive, but they are still treatable.

In addition to staging breast cancer, the AJCC recommends tissue testing to better determine which treatments are likely to be most effective. Breast cancer tumors are tested for estrogen and progesterone receptors (ER/PR) and human epidermal growth factor receptor-2 (HER2).

Table 1. Stages of Breast Cancer

Stage TNM Classification
0 Tis, N0, M0
IA T1*, N0, M0
IB T0 or T1*, N1mi, M0
IIA T0 or T1*, N1**, M0
T2, N0, M0
IIB T2, N1, M0
T3, N0, M0
IIIA T0-T3, N2, M0
T3, N1, M0
IIIB T4, N0-N2, M0
IIIC Any T, N3, M0
IV Any T, Any N, M1

*T1 includes T1mi.

**T0 and T1 tumors with micrometastases in node(s) only are excluded from Stage IIA and are classified Stage IB.

Table 2. American Joint Committee on Cancer System for Classifying Breast Cancers

Category Definition
T Size of tumor
Tx The tumor cannot be assessed
T0 No evidence or primary tumor
Tis Known as carcinoma in situ, the tumor has not started growing into the breast tissue 
Tumor is 2 centimeters (about ¾ inch) or less
Tumor is 1 millimeter or less
Tumor is larger than 1 mm but not more than 5 mm (0.5 cm)
Tumor is larger than 5 mm but not more than 10 mm (1 cm)
Tumor is larger than 10 mm but not more than 2 cm
T2 Tumor is larger than 2 cm but not more than 5 cm (almost 2 inches)
T3 Tumor is larger than 5 cm

Tumor may be any size but has grown into the chest wall and/or into the skin
Tumor extends into the chest wall
The skin shows the presence of one or more of the following: edema (swelling), ulceration
  (a sore, painful area where the breast skin/tissue is breaking down), or satellite skin nodules
  (additional tumor masses) in the same breast
Signs of both T4a and T4b are present
Breast is red, swollen and warm, indicating inflammatory carcinoma
N Number and location of lymph nodes
Nx Lymph nodes cannot be evaluated
N0 No metastasis or micrometastasis* found in any lymph nodes

Micrometastases* are found in lymph nodes (more than 0.2 mm but no more than 2 mm)
Cancer cells have spread to 1 to 3 axillary lymph nodes (nodes under the arm), with at least one      metastasis of more than 2 mm (0.2 cm)
Cancer cells have spread to internal mammary lymph nodes (nodes on either side of the sternum   [breastbone]), not detected by physical exam or imaging
Cancer cells have spread to 1 to 3 axillary lymph nodes and in internal mammary lymph nodes

Cancer cells have spread to 4 to 9 axillary lymph nodes
Cancer cells have spread to clinically detected internal mammary lymph nodes but not to axillary
  lymph nodes



Cancer cells have spread to 10 or more axillary lymph nodes OR in the infraclavicular lymph nodes   (nodes under the clavicle [collarbone])

Cancer cells have spread to clinically detected internal mammary lymph nodes and in 1 or more   axillary lymph nodes

Cancer cells have spread to supraclavicular lymph nodes (nodes above the clavicle)
M Metastasis
M0 Cancer has not spread to other parts of the body (beyond the breast and local lymph nodes)
cM0(i+) There is no evidence of cancer spread, but deposits of tumor cells can be detected at the
  microscopic or molecular level in the blood, bone marrow or other nodal tissue
M1 There is clinical evidence that cancer has spread to other parts of the body

*Refers to a small cluster of tumor cells, no larger than 2 millimeters.


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