Once breast cancer is diagnosed, further tests are performed to determine if the cancer has spread. This process is known as breast cancer staging. The stage determines the appropriate treatment options.
Stage 0
Stage 0 describes non-invasive breast cancers. In this stage, there is no evidence of cancer cells or noncancerous abnormal cells beyond the site of origin. There are two types of stage 0, ductal carcinoma in situ and lobular carcinoma in situ.
Ductal carcinoma in situ (DCIS) is a noninvasive condition in which abnormal cells occur in the lining of a breast duct and have not spread to surrounding tissue.
DCIS may become invasive. Lobular carcinoma in situ (LCIS) is a condition in which abnormal cells are found in the lobules of the breast and seldom becomes invasive.
Stage 1
Stage 1 describes invasive breast cancers and is subdivided into stage 1A and stage 1B. A stage 1A tumor is 2 centimeters or smaller and has not spread outside of the breast.
Stage 1B describes a small cluster of cancer cells, which measure between 0.2 and 2 millimeters, that are found in the lymph nodes with no tumor in the breast. Stage 1B also describes a tumor, which is 2 centimeters or smaller and a small cluster of cancer cells, which measure between 0.2 and 2 millimeters, found in the lymph nodes.
Stage 2
Stage 2 is divided into stage 2A and stage 2B. Stage 2A describes cancer found in the lymph nodes under the arm but not in the breast; a tumor that is 2 centimeter or smaller and has spread to the axillary lymph nodes, which are located under the arm; or a tumor that is between 2 to 5 centimeters and has not spread to the axillary lymph nodes.
Stage 2B describes an invasive tumor that is either larger than 2 centimeters but less than 5 centimeters and has spread to the axillary lymph nodes; or an invasive tumor that is larger than 5 centimeters and has not spread to the axillary lymph nodes.
Stage 3
Stage 3 is divided into three subcategories. Stage 3A describes cancer that is found in the axillary lymph nodes, which are attached to each other or to other structures; cancer found in the lymph nodes near the breastbone with no tumor found in the breast; or a tumor of any size with metastasis to the axillary lymph nodes, which are attached to each other or to other structures.
Stage 3B describes a tumor of any size that has spread to the chest wall, and/or the skin of the breast and may have spread to the axillary lymph nodes, which are attached to each other or to other structures as well as to the lymph nodes near the breastbone.
Stage 3C describes invasive cancer with no sign of cancer in the breast; a tumor of any size that has spread to the chest wall and/or to the skin of the breast and to the lymph nodes above or below the collarbone, axillary lymph nodes or the lymph nodes near the breastbone. Stage 3C is subcategorized as operable and inoperable.
Operable stage 3C cancers are found in 10 or more axillary lymph nodes or in the lymph nodes below the collar bone or in the axillary lymph nodes and the lymph nodes near the breastbone.
Inoperable stage 3C describes cancer that has spread to the lymph nodes above the collarbone.
Stage 4
Stage 4 describes invasive cancer that has spread beyond the breast and surrounding lymph nodes to other organs of the body such as the lungs, distant lymph nodes, skin, bones, liver or brain. This stage is also referred to as advanced or metastatic breast cancer.
TNM staging system
Researchers working on clinical trials for breast cancer will use the TNM staging system, which provides more information on how the cancer appears and how it behaves. T stands for size of the tumor, N signifies lymph node involvement and M represents where the cancer has spread.
Sources
BreastCancer.org: Stages of Breast Cancer, Sept. 13, 2011
http://www.breastcancer.org/symptoms/diagnosis/staging.jsp#stage0
National Cancer Institute: Breast Cancer Treatments, Sept. 13, 2011
http://www.cancer.gov/cancertopics/pdq/treatment/breast/Patient/page2#Keypoint11
Reviewed September 16, 2011
by Michele Blacksberg RN
Edited by Malu Banuelos