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 (chance of survival). 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 have been used to classify stage.

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

No matter if you were staged before 2018 or since 2018, your breast cancer treatment was guided by the same factors including hormone receptor status and HER2 status.

Learn about breast cancer stages and staging since 2018.

Breast cancer staging

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

Clinical staging includes results from a health care provider’s physical exam, tests and/or imaging, such as mammography. Sometimes, these findings may add to the pathologist’s findings and may help with staging.

TNM system of staging for breast cancers diagnosed before 2018

The main 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)

A “p” before the T or N shows these are pathology findings from the tumor or lymph nodes removed during surgery.

Before 2018, stage depended on the combination of just these 3 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 (chance of survival). 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 (DCIS)
	Tis (LCIS): Lobular carcinoma in situ (LCIS)
	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 lymph nodes) contain cancer:

Lymph node-negative means none of the axillary lymph nodes contain cancer.
Lymph node-positive means at least one axillary lymph node contains cancer.

Prognosis (chance of survival) is better when cancer has not spread to the lymph nodes (lymph node-negative).

The more lymph nodes that contain cancer, the poorer the prognosis tends to be.

See Figure 4.4 for a drawing of the breast and lymph nodes.

How is lymph node status assessed?

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

Usually, a surgeon removes one or more axillary lymph nodes with a technique called sentinel node biopsy. 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. This is 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 aren’t 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 don’t have cancer when looked at under a microscope	Axillary and other nearby lymph nodes don’t have cancer
N1	Micrometastases (very small clusters of cancer) OR 1–3 axillary lymph nodes have cancer AND/OR Internal mammary nodes have cancer or micrometastases (very small clusters of cancer cells) 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 don’t 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 don’t appear to have cancer
N3	10 or more axillary lymph nodes have cancer OR Infraclavicular (under the clavicle (collarbone)) nodes have cancer OR Internal mammary nodes have cancer plus 1 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 hasn’t (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 breast cancer with metastases (M1), no matter the size of the tumor or the lymph node status. This is known as metastatic breast cancer and is the most advanced stage of disease.

Most often, the higher the stage of the cancer, the poorer the prognosis (chance of survival) 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 (DCIS)
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

Updated 12/20/22

TOOLS & RESOURCES

Give For Metastatic Breast Cancer Research

Donate Now