How breast cancer is staged

The stageinfo-icon of a breast cancer describes the extent of the cancer in your breast and in the body.

When doctors stage the breast cancer, they look at these factors:

  • how far the cancer has spread, using a system called TNM (tumorinfo-icon, lymphinfo-icon nodes, metastasisinfo-icon)
    • the size of the tumor (T)
    • whether lymph nodes near the breast contain breast cancer (N)
    • whether the breast cancer has spread from the breast to other parts of the body (M)
  • characteristics of the cancer cells that show how the cancer is behaving

In some cases, Oncotype Dx score, which measures the risk of recurrenceinfo-icon, is part of staginginfo-icon.

Breast cancer stages can be clinicalinfo-icon or pathological. The clinical stageinfo-icon is based on a physical exam by your doctor and any scans, including mammograminfo-icon, ultrasound, and MRIinfo-icon, that you have had. Pathologic stage is based on what is found during surgeryinfo-icon to remove the cancer. Pathologic stage is more precise, but clinical stage may be use to guide treatments given before surgery.

Stage is one piece of information doctors use to understand how well a treatment might work. Stage, along with other factors including advances in treatment, is also used to estimate survival rates.

Stage 0

Stage 0 breast cancer is noninvasiveinfo-icon. This means the cancer cells are contained inside of the ducts of the breast and no cancer cells can be seen breaking through to surrounding breast tissueinfo-iconDuctal carcinoma in situinfo-icon, or DCISinfo-icon, is stage 0 breast cancer.

Stage I

Stage I breast cancers are invasive. This means that the cancer has broken through the ducts or lobules into surrounding breast tissue. Stage I breast cancers are 2 centimeters or smaller in size. Usually, these cancers have not traveled to the lymph nodes.

Stage I breast cancerinfo-icon falls into two groups: stages IA and IB.

  • Stage IA breast cancers usually have the following characteristics:
    • The tumor is 2 centimeters (about the size of a peanut without the shell) or smaller. This can include very small tumors of less than 1 millimeter (microinvasive breast cancer).
    • There is no cancer in the lymph nodes.
    • The cancer has not spread beyond the breast to any other organs. 
       
  • Stage IB breast cancers include these situations:
    • There is no evidence of a breast tumor, but there are small areas of cancer in the underarm (axillary) lymph nodes measuring at least 0.2 millimeters but are no larger than 2 millimeters in size, called micrometastasisinfo-icon.
    • There is a breast tumor that is 2 centimeters or less across, including as small as 1 millimeter or less (microinvasive breast cancer), and there are small areas of cancer in the axillary lymph nodes (micrometastasis) measuring at least 0.2 millimeters but are no larger than 2 millimeters in size. 
    • In all cases of stage IB breast cancerinfo-icon, the cancer has not spread to any other organs

Hormone receptorinfo-icon status, HER2 status, and cancer grade are also factors in determining whether a cancer is stage I.

Stage II

Stage II breast cancers fall into two groups: IIA and IIB.

  • Stage IIA includes these situations:
    • There isn’t any evidence of a breast tumor, but there is cancer in one to three axillary lymph nodes or internal mammary lymph nodesinfo-icon (near the breast bone, identified with sentinel lymph node biopsyinfo-icon). 
    • The tumor is 2 centimeters or less across and there is cancer in one to three axillary lymph nodes and/or internal mammary lymph nodes. 
    • The tumor is between 2 and 5 centimeters across and there is no cancer in the lymph nodes.
    • In all cases, cancer has not spread beyond the breast to any other organs. 
       
  • Stage IIB includes these situations:
    • The tumor is between 2 and 5 centimeters across and there is cancer in one to three axillary lymph nodes or internal mammary lymph nodes (near the breast bone, sometimes identified with sentinel node biopsyinfo-icon).
    • The tumor is more than 5 centimeters across and there is no cancer in the lymph nodes, or a tiny amount of cancer has been detected in lymph nodes at a size smaller than 0.2 millimeters.
    • In all cases, cancer has not spread beyond the breast to any other organs.

Hormone receptor status, HER2 status, and cancer grade are also factors in determining whether a cancer is stage II.

Stage III

Stage III breast cancers fall into three groups: stages IIIA, IIIB, and IIIC.

  • Stage IIIA includes these situations:
    • There is no evidence of a tumor, or there is a tumor of any size and cancer is found in four to nine axillary lymph nodes, or the cancer has caused the internal mammary lymph nodes near the breast bone to become enlarged.
    • The tumor is larger than 5 centimeters across and there is cancer in one to three axillary lymph nodes or internal mammary lymph nodes near the breast bone, found during a sentinel node biopsy.
    • In all cases, the cancer has not spread to distant organs such as the bones, lungs, or liver.
       
  • Stage IIIB includes these situations:
    • The tumor may be of any size that has grown into the skin or the chest wallinfo-icon.
    • Cancer may be found in 0 to 9 axillary lymph nodes.
    • Cancer may have one or more enlarged internal mammary lymph nodes near the breast bone.
    • The breast cancer may also be inflammatory. Inflammatory breast cancerinfo-icon is breast cancer that has certain physical signs that appear and worsen quickly, these can include breast redness, warmth, swelling, or an “orange peel” look on the breast skin. Inflammatory breast cancer usually does not form a lump and may not be found in a mammogram. Inflammatory breast cancers can be hormone receptor positive, HER2 positive, or triple negative.
    • In all cases, the cancer has not spread to distant organs such as bones, lungs, or liver.
       
  • Stage IIIC breast cancers may have a tumor of any size or no tumor at all, when cancer is found
    • in 10 or more axillary lymph nodes in any number of internal mammary lymph nodes near the breast bone
    • in a combination of axillary and internal mammary lymph nodes
    • in supraclavicular lymph nodes (lymph nodes near the collarbone)
    • to be inflammatory breast cancer. This means it has certain physical signs that appear and worsen quickly, these can include breast redness, warmth, swelling, or an “orange peel” look on the breast skin. Inflammatory breast cancer usually does not form a lump and may not be found in a mammogram. Inflammatory breast cancers will also be either hormone receptor-positive, HER2-positive, or triple negative.
    • to have not spread to distant organs such as bones, lungs, or liver.

Hormone receptor status, HER2 status, and cancer grade are also factors in determining whether a cancer is stage III.

Stage IV

Stage IV or metastatic breast cancer is invasive cancerinfo-icon that has spread beyond the breast to other parts of the body. Common locations of spread can include

  • Lymph nodes in distant parts of the body
  • The chest wall
  • The bones, liver, lungs, or brain

Stage IV breast cancerinfo-icon is often a recurrence, or the return of a previous breast cancer. If stage IV is the very first diagnosisinfo-icon of breast cancer, it’s often called de novoinfo-icon (“starting from the beginning”) metastaticinfo-icon breast cancer.

Advanced breast cancer vs. metastatic breast cancer

You might hear stage IV breast cancer referred to as advanced or metastatic. It’s important to know that “advanced” can mean stage IV breast cancer, but it can also refer to “locally advanced” breast cancer. Locally advanced breast cancer has spread to areas near the breast, including lymph nodes, skin, and/or the chest wall, but not to other locations of the body. Inflammatory breast cancer can be locally advanced or metastatic.

The TNM system

After you receive a breast cancer diagnosis, your doctor may ask for radiologyinfo-icon tests, more biopsies, a physical exam and more details from you about your symptoms. With all this information, your doctor will assign a stage to the breast cancer using the American Joint Committee on Cancer TNM system.

The TNM system is the most widely used systems to describe the stages of breast cancer. Most cancer care teams use the TNM system as a standard way to describe how far the cancer has spread. Doctors use the TNM stage of the cancer to make decisions about which treatments are best for you.

Each letter in the TNM system is assigned a number to show the size of the original tumor and how far the cancer has spread. Here, we’ll walk you through what it all means.

T

  • T stands for tumorinfo-icon. The T stageinfo-icon is determined by the size of the tumor and whether it has affected the skin over the breast or the muscle beneath the breast.
  • T includes these categories for breast cancer:
    • TX means the size of the tumor can’t be determined
    • T0 means there is no evidence of the primary tumorinfo-icon
    • Tis means the cancer is “in situinfo-icon” (DCISinfo-icon, LCIS, or Paget disease of the breast with no tumor massinfo-icon)
    • T1 tumors are 2 centimeters or less across
    • T2 tumors are larger than 2 centimeters but less than 5 centimeters across
    • T3 tumors are larger than 5 centimeters across
    • T4 cancers have spread into the chest wallinfo-icon or skin, or are inflammatory breast cancerinfo-icon

N

  • N stands for lymphinfo-icon nodes. The N stageinfo-icon is determined either by
    • the number of lymph nodes in the armpit, called axillary nodes, that have cancer
    • the number of nodes near the breast bone in the center of the chest, called internal mammaryinfo-icon nodes, that have cancer
    • the number of nodes in the base of the neck near the collarbone, called supraclavicular nodes, that have cancer
    • N includes these categories for breast cancer:
      • NX means that it can’t be determined whether the cancer is in nearby lymph nodes
      • N0 means cancer has not traveled to nearby lymph nodes
      • N1 means cancer is in one to three armpit lymph nodes, in lymph nodes near the breast bone, or in both
      • N2 means cancer is in four to nine armpit lymph nodes, in the lymph nodes near the breast bone, or in both
      • N3 means cancer is in 10 or more armpit lymph nodes, or in the lymph nodes near the collarbone, or in lymph nodes near the breast bone, or in some combination of these

M

  • M stands for metastasisinfo-icon. The M stageinfo-icon is determined by whether the cancer has traveled from your breast and nearby lymphinfo-icon nodes to another area in your body.
  • M includes these categories for breast cancer:
    • MX means it can’t be determined whether or not the cancer has metastasized
    • M0 means the cancer hasn’t metastasized
    • M1 means the cancer has metastasized to other organs including the bones, lungs, liver, or brain
Updated 
May 4, 2021
Reviewed By: