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Breast Cancer Treatment and Pregnancy

Stages of Breast Cancer

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 if 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.

Methods used to stage breast cancer can be changed to make them safer for the fetus.

Standard methods for giving imaging scans can be adjusted so that the fetus is exposed to less radiation. Tests to measure the level of hormones in the blood may also be used in the staging process.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for breast cancer:

Stage 0 (carcinoma in situ)

There are 2 types of breast carcinoma in situ:


Pea, peanut, walnut, and lime show tumor sizes.
Pea, peanut, walnut, and lime show tumor sizes.

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

In stage IIIA:

Stage IIIB

In stage IIIB, the tumor may be any size and cancer:

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

Stage IIIC

In stage IIIC, there may be no sign of cancer in the breast or the tumor may be any size and may have spread to the chest wall and/or the skin of the breast. Also, cancer:

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

Stage IIIC breast cancer is divided into operable and inoperable stage IIIC.

In operable stage IIIC, the cancer:

In inoperable stage IIIC breast cancer, the cancer has spread to the lymph nodes above the collarbone.

Stage IV

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