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Breast Cancer Stages

Key Points

  • After breast cancer has been diagnosed, tests are done to find out if cancer cells have spread within the breast or to other parts of the body.
  • There are three ways that cancer spreads in the body.
  • Cancer may spread from where it began to other parts of the body.
  • The following stages are used for breast cancer:
    • Stage 0 (carcinoma in situ)
    • Stage I
    • Stage II
    • Stage IIIA
    • Stage IIIB
    • Stage IIIC
    • Stage IV

After breast cancer has been diagnosed, tests are done to find out if cancer cells have spread within the breast or to other parts of the body.

The process used to find out whether the cancer has spread within the breast or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests and procedures may be used in the staging process:

There are three ways that cancer spreads in the body:

Cancer can spread through tissue, the lymph system, and the blood:

Cancer may spread from where it began to other parts of the body.

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bone, the cancer cells in the bone are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

Breast Cancer Stages

The following stages are used for breast cancer:

This section describes the stages of breast cancer. The breast cancer stage is based on the results of testing that is done on the tumor and lymph nodes removed during surgery and other tests.

Stage 0 (carcinoma in situ)

There are 3 types of breast carcinoma in situ:

Stage I

In stage I, cancer has formed. Stage I is divided into stages IA and IB.

Stage II

Stage II is divided into stages IIA and IIB.

Stage IIIA

Stage IIIB

In stage IIIB, the tumor may be any size and cancer has spread to the chest wall and/or to the skin of the breast and caused swelling or an ulcer. Also, cancer may have spread to:

Cancer that has spread to the skin of the breast may also be inflammatory breast cancer. See the section on Inflammatory Breast Cancer for more information.

Stage IIIC

In stage IIIC, no tumor is found in the breast or the tumor may be any size. Cancer may have spread to the skin of the breast and caused swelling or an ulcer and/or has spread to the chest wall. Also, cancer has spread to:

Cancer that has spread to the skin of the breast may also be inflammatory breast cancer.

For treatment, stage IIIC breast cancer is divided into operable and inoperable stage IIIC.

Stage IV

In stage IV, cancer has spread to other organs of the body, most often the bones, lungs, liver, or brain.


Reference: National Cancer Institute

Last updated: February 9, 2018