Defining the Stages of Breast Cancer

To plan a woman's treatment, the doctor needs to know the extent or stage of the disease.

• The stage is based on the size of the tumor and whether the cancer has spread from the breast.
• Determining the stage of the disease may involve x-rays and lab tests to learn whether the cancer has spread and, if so, to what parts of the body.
• When breast cancer spreads, cancer cells are often found in lymph nodes under the arm (axillary lymph nodes).

View the anatomy of the breast.

The extent of the cancer often is not known until after surgery to remove the tumor in the breast and the lymph nodes under the arm.

Doctors describe breast cancer by the following stages:

• Early stages of breast cancer: stages 0, I, II
• Later stage of breast cancer: stage III (and stage II if many lymph nodes are involved)
• Advanced stage of breast cancer: stage IV

Early Stages of Breast Cancer

In early-stage breast cancer, cancer cells are located only in the breast, or, at most, they have spread to a few lymph nodes in the armpit. (Lymph nodes are small collections of white blood cells from the immune system located throughout the body that act as filters.)

• The size of the cancer is less than two inches in diameter.
• Early-stage breast cancer is further classified into three different stages: 0, I, and II.
• For stage II cancers, if there are cancer cells in many lymph nodes in the armpit, many doctors would consider these cancers to be more locally advanced and not early-stage.

Doctors use the following staging system to precisely define where the cancer is located:

 

		Stage 0 Cancer cells are present in either the lining of the glands that make milk (lobules) or the tubes (ducts) that link these glands to the nipple. But cancer cells have not spread to the nearby fatty tissue.
		Stage I Cancer has spread from the lobules or ducts to nearby tissue in the breast. The size of the tumor is approximately one inch (two centimeters) or less in diameter. Cancer cells have not spread to surrounding lymph nodes. Lymph nodes are small clumps of immune cells that act as filters.
		Stage II Cancer has spread from the lobules or ducts to nearby tissue in the breast. The size of the tumor can range from approximately one to two inches (two to five centimeters). Sometimes cancer cells have also spread to the lymph nodes.

Later Stage of Breast Cancer (Locally Advanced)

 

		Stage III Tumors that are approximately two inches (five centimeters) or larger, or tumors of any size that have spread to: Lymph nodes under the arm (axillary) that are attached to each other or surrounding tissue, or Lymph nodes in the chest or above or below the collarbone Tumors that have spread to other tissues near the breast may also be considered stage III. Stage III disease may also be described as locally advanced cancer.

Advanced Stage of Breast Cancer (Metastatic)

 

		Stage IV Cancer that has spread from the breast and lymph nodes to other parts of the body, such as the bone, liver, lungs, or brain, is known as metastatic cancer.

Anatomy of the Breast

• A breast is made up of fatty tissue, ducts, lobules, blood vessels, and lymph vessels.
• The fatty tissue surrounds the lobules and ducts.
• There are lymph nodes throughout the body.