Breast Cancer Stages and Staging Before 2018

Breast cancer stage describes the extent of the cancer within your body.

Breast cancer stage is the most important factor for prognosis. In general, the earlier the stage, the better the prognosis will be.

If you were diagnosed before 2018, your breast cancer was staged a bit differently than it would be today.

Before 2018, stage was determined by 3 measures:

  • Tumor size
  • Lymph node status (the number and location of lymph nodes with cancer)
  • Metastases (whether or not the cancer has spread to other areas of the body)

Starting in 2018, more measures are used to classify stage.

If you were diagnosed before 2018, this page has information on how your breast cancer was staged.

Learn about breast cancer stages and staging since 2018.

Breast cancer staging

Pathologic staging is based on a pathologist’s study of the tumor tissue and any lymph nodes removed during surgery. It’s the standard way to stage breast cancer.

Sometimes, results from a health care provider’s physical exam and/or tests such as mammography may help with staging.

TNM system of staging for breast cancers diagnosed before 2018

The most widely used method of pathologic staging for breast cancer is 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 areas of the body)

Stage depends on the combination of these measures.

For detailed information on staging and tumor size, lymph node status and the presence or absence of metastases, click on the drawers below.

Tumor size is strongly related to prognosis. In general, the smaller the tumor, the better prognosis tends to be.

A “T” followed by a number shows the size of the tumor. A diagnosis of carcinoma in situ is written as Tis.

In some cases, the size of the tumor cannot be determined (TX) or a tumor cannot be found (TO).

Tumor size categories for breast cancers diagnosed before 2018

TX: Tumor size cannot be assessed

T0: No tumor can be found

Tis: Carcinoma in situ

 

Subcategories of Tis:

 

Tis (DCIS): Ductal carcinoma in situ

 

Tis (LCIS): Lobular carcinoma in situ

 

Tis (Paget): Paget disease of the breast (Paget disease of the nipple) with no DCIS, LCIS or invasive breast cancer

T1: Tumor is 2 cm or smaller

 

Subcategories of T1:

 

T1mi: Very small tumor (0.1 cm or smaller)

 

T1a: Tumor is larger than 0.1 cm, but no larger than 0.5 cm

 

T1b: Tumor is larger than 0.5 cm, but no larger than 1 cm

 

T1c: Tumor is larger than 1 cm, but no larger than 2 cm

T2: Tumor is larger than 2 cm, but no larger than 5 cm

T3: Tumor is larger than 5 cm

T4: Tumor is any size, but has spread beyond the breast tissue to the chest wall and/or skin

 

Subcategories of T4:

 

T4a: Tumor has spread to the chest wall

 

T4b: Tumor has spread to the skin, but is not inflammatory breast cancer

 

T4c: Tumor has spread to both the chest wall and skin

 

T4d: Inflammatory breast cancer

Learn more about tumor size.

Lymph node status shows whether or not the lymph nodes in the underarm area (axillary nodes) contain cancer:

  • Lymph node-negative means the lymph nodes do not contain cancer.
  • Lymph node-positive means the lymph nodes contain cancer.

Prognosis is poorer when cancer has spread to the lymph nodes (lymph node-positive). The more lymph nodes that contain cancer, the poorer the prognosis tends to be.  

See Figure 4.4 for an illustration of the breast and lymph nodes.

How is lymph node status assessed?

A pathology exam is the best way to assess lymph node status (called pathologic lymph node status).

Usually, a surgeon removes one or more axillary lymph nodes with a technique called sentinel node biopsy. Then, a pathologist studies these nodes under a microscope to see if they contain cancer.

A physical exam (also called a clinical exam) can give a first estimate of lymph node status (called clinical lymph node status). Enlarged nodes can be a sign the breast cancer has spread to the nodes.

Clinical lymph node status is only used when pathologic findings are not available.

In breast cancer staging, an “N” followed by a number and/or letters shows the lymph node status.

 Categories for breast cancers diagnosed before 2018

 

Pathologic lymph node status

Clinical lymph node status
(only used when pathologic findings are not available) 

NX

Axillary and other nearby lymph nodes cannot be assessed (for example, they were not removed during surgery)

Axillary and other nearby lymph nodes cannot be assessed (for example, they were removed in the past)

N0

Axillary and other nearby lymph nodes do not have cancer (when looked at under a microscope)

Axillary and other nearby lymph nodes do not have cancer

N1

Micrometastases (very small clusters of cancer) OR 

1–3 axillary lymph nodes have cancer AND/OR  

Internal mammary nodes have tiny amounts of cancer found on sentinel node biopsy

Axillary lymph nodes have cancer, but can be moved around

N2 

4–9 axillary lymph nodes have cancer OR

Internal mammary nodes have cancer, but axillary lymph nodes do not have cancer

Axillary lymph nodes have cancer and are matted together or fixed to other structures (such as the chest wall) OR

Internal mammary nodes have cancer, but axillary lymph nodes do not appear to have cancer

N3

10 or more axillary lymph nodes have cancer OR

Infraclavicular (under the clavicle) nodes have cancer OR

Internal mammary nodes have cancer plus one or more axillary lymph nodes have cancer OR 

4 or more axillary lymph nodes have cancer plus internal mammary nodes have cancer or micrometastases found on sentinel node biopsy OR

Supraclavicular (above the clavicle) nodes have cancer

Infraclavicular (under the clavicle) nodes have cancer (axillary lymph nodes may or may not have cancer) OR

Internal mammary nodes and axillary lymph nodes have cancer OR

Supraclavicular (above the clavicle) nodes have cancer (axillary lymph nodes may or may not have cancer)

Learn more about lymph node status.

The letter “M’ in the TNM breast cancer staging system shows the presence or absence of metastases.

Cancer has either spread beyond the breast and nearby lymph nodes to other areas of the body (M1) or it has not (M0).

MX

Metastases cannot be assessed

M0

No metastases

M1

Metastases

Learn about treatment for metastatic breast cancer.

Stages of breast cancer diagnosed before 2018

The stages of breast cancer range from 0 to IV (0 to 4).

The highest stage (stage IV) is any cancer with metastases (M1), no matter the size of the tumor or the lymph node status.

Most often, the higher the stage of the cancer, the poorer the prognosis will be.

The table below lists the TNM classifications (for breast cancer diagnosed before 2018) for each stage.

Stages for breast cancer diagnosed before 2018

Ductal carcinoma in situ

Stage 0

TisN0M0

Early breast cancer

Stage Ia

T1N0M0

Stage Ib

T0N1miM0

T1N1miM0

Stage IIa

T0N1M0

T1N1M0

T2N0M0

Locally advanced breast cancer

Stage IIb

T2N1M0

T3N0M0

Stage IIIa

T0N2M0

T1N2M0

T2N2M0

T3N1M0

T3N2M0

Stage IIIb

T4N0M0

T4N1M0

T4N2M0

Stage IIIc

Any T, N3M0

Metastatic breast cancer

Stage IV

Any T, any N, M1

 

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