user: What are the stages of Breast Cancer ?

assistant: 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        - The treatment of breast cancer depends partly on the stage of the disease.
                
                
                    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 results of some of the tests used to diagnose breast cancer are also used to stage the disease. (See the General Information section.)    The following tests and procedures also may be used in the staging process:         -   Sentinel lymph node biopsy : The removal of the sentinel lymph node during surgery. The sentinel lymph node is the first lymph node to receive lymphatic drainage from a tumor. It is the first lymph node the cancer is likely to spread to from the tumor. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes.     -   Chest x-ray : An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.    -   CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.     -   Bone scan : A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner.    -   PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
                
                
                    There are three ways that cancer spreads in the body.
                    Cancer can spread through tissue, the lymph system, and the blood:         - Tissue. The cancer spreads from where it began by growing into nearby areas.     - Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.     - Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
                
                
                    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.         - Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.    - Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.        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.
                
                
                    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 tests that are done on the tumor and lymph nodes removed during surgery and on other tests.     Stage 0 (carcinoma in situ)    There are 3 types of breast carcinoma in situ:            -  Ductal carcinoma in situ (DCIS) is a noninvasive condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, DCIS may become invasive cancer and spread to other tissues. At this time, there is no way to know which lesions could become invasive.     -  Lobular carcinoma in situ (LCIS) is a condition in which abnormal cells are found in the lobules of the breast. This condition seldom becomes invasive cancer. Information about LCIS is not included in this summary.     -  Paget disease of the nipple is a condition in which abnormal cells are found in the nipple only.               Stage I      In stage I, cancer has formed. Stage I is divided into stages IA and IB.            - In stage IA, the tumor is 2 centimeters or smaller. Cancer has not spread outside the breast.     - In stage IB, small clusters of breast cancer cells (larger than 0.2 millimeter but not larger than 2 millimeters) are found in the lymph nodes and either:                  - no tumor is found in the breast; or       - the tumor is 2 centimeters or smaller.                         Stage II     Stage II is divided into stages IIA and IIB.            - In stage IIA:                  - no tumor is found in the breast or the tumor is 2 centimeters or smaller. Cancer (larger than 2 millimeters) is found in 1 to 3 axillary lymph nodes or in the lymph nodes near the breastbone (found during a sentinel lymph node biopsy); or        - the tumor is larger than 2 centimeters but not larger than 5 centimeters. Cancer has not spread to the lymph nodes.                - In stage IIB, the tumor is:                  - larger than 2 centimeters but not larger than 5 centimeters. Small clusters of breast cancer cells (larger than 0.2 millimeter but not larger than 2 millimeters) are found in the lymph nodes; or        - larger than 2 centimeters but not larger than 5 centimeters. Cancer has spread to 1 to 3 axillary lymph nodes or to the lymph nodes near the breastbone (found during a sentinel lymph node biopsy); or        - larger than 5 centimeters. Cancer has not spread to the lymph nodes.                          Stage IIIA     In stage IIIA:            - no tumor is found in the breast or the tumor may be any size. Cancer is found in 4 to 9 axillary lymph nodes or in the lymph nodes near the breastbone (found during imaging tests or a physical exam); or      - the tumor is larger than 5 centimeters. Small clusters of breast cancer cells (larger than 0.2 millimeter but not larger than 2 millimeters) are found in the lymph nodes; or      - the tumor is larger than 5 centimeters. Cancer has spread to 1 to 3 axillary lymph nodes or to the lymph nodes near the breastbone (found during a sentinel lymph node biopsy).               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:             - up to 9 axillary lymph nodes; or     - the lymph nodes near the breastbone.           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:             - 10 or more axillary lymph nodes; or     -  lymph nodes above or below the collarbone; or     - axillary lymph nodes and lymph nodes near the breastbone.           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 IV     In stage IV, cancer has spread to other organs of the body, most often the bones, lungs, liver, or brain.
                
                
                    The treatment of breast cancer depends partly on the stage of the disease.
                    For ductal carcinoma in situ (DCIS) treatment options, see Ductal Carcinoma in Situ.   For treatment options for stage I, stage II, stage IIIA, and operable stage IIIC breast cancer, see Early, Localized, or Operable Breast Cancer.   For treatment options for stage IIIB, inoperable stage IIIC, and inflammatory breast cancer, see Locally Advanced or Inflammatory Breast Cancer.   For treatment options for cancer that has recurred near the area where it first formed, see Locoregional Recurrent Breast Cancer.   For treatment options for stage IV breast cancer or breast cancer that has recurred in other parts of the body, see Metastatic Breast Cancer.