In simple terms, staging refers to the extent of cancer in your body. In addition to a physical exam and biopsy, your doctor may suggest that you have imaging tests such as chest x-ray, bone scans, mammograms of each of your breasts, CT, MRI or PET scans. Blood tests can give a picture of your overall health and determine if the cancer has spread to some of your organs. Breast cancer staging is necessary to determine your course of treatment as well as your survival rate.
Stage 0 refers to the earliest form of breast cancer, such as ductal carcinoma in situ, sometimes called DCIS, a non-invasive cancer. In this type cancer, the cells remain inside a duct and have not gone into the nearby fatty breast tissue. Lobular carcinoma in situ, called LCIS, is sometimes classified as a stage 0 cancer, but there is disagreement as to whether it is a true breast cancer. In LCIS, abnormal cells grow within the glands that produce milk but do not penetrate their walls. The American Cancer Society reports that the five-year survival rate for stage 0 is 93 percent. The numbers for this and successive stages come from the National Cancer Data Base from individuals diagnosed with breast cancer in 2001 and 2002. Improvements in treatment may create a more favorable outlook for those diagnosed now, and there are many individual variations.
Still a very early breast cancer stage, stage I pertains to invasive breast cancer in which malignant cells break through to nearby normal tissue. In this stage the size of the tumor is 2 centimeters or less and there is no lymph node involvement. The American Cancer Society gives this five-year survival rate as 88 percent.
Stage II has two categories: IIA and IIB. Any of the following may be true of stage IIA: there is not a tumor in the breast, but malignant cells exist in the axillary lymph nodes under the arm; or the tumor is 2 centimeters or under and is found in the axillary lymph nodes; or the tumor is between 2 and 5 centimeters but is not found in the axillary lymph nodes.
In stage IIB invasive breast cancer the tumor size is between 2 and 5 centimeters and has also spread to the axillary nodes or is larger than 5 centimeters but has not spread to the lymph nodes under the arm. Five-year survival rates for IIA and IIB are 81 ad 74 percent, respectively.
Stage III has three components — A, B and C. Any of the following may occur with stage IIIA: no tumor has been located in the breast, but cells are found under the arm that are either clumped together or sticking to other structures or may have spread to the nodes close to the breastbone; or the tumor is up to 5 centimeters in size and has spread to lymph nodes under the arm that are sticking to other structures or clumped together; or the size is over 5 centimeters and has spread to axillary lymph nodes clumped together or sticking to other structures. Its survival rate is 67 percent.
In stage IIIB, the tumor could be any size, but has invaded the chest wall or skin of the breast plus may have spread to lymph nodes under the arm that are clumped together or sticking to other things, or cells may be located in the nodes near the breastbone. The five-year survival rate is 41 percent. Inflammatory breast cancer is viewed as at least IIIB.
Stage IIIC is indicative of malignancy in which there may be no cells found in the breast, but if there are, the tumor could be any size, may have spread to either the skin of the breast or the chest wall, and the cancer is found in the nodes above or below the collarbone, and may have invaded the lymph nodes either under the arm or near the breastbone. The five-year survival rate is 49 percent.
Stage IV is considered an advanced stage of breast cancer staging, because the cancer has metastasized to other organs. The most likely places for it to go to are the lungs, liver, bone or brain. The term "metastatic at presentation" is used to denote that the malignancy has spread beyond the breast and neighboring nodes, even at first diagnosis. The five-year survival rate is 15 percent. Bear in mind that many things determine survival rate, and even if you are diagnosed with stage IV cancer, you do not need to give up hope.
American Cancer Society: https://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-staging
American Cancer Society: https://www.cancer.org/Cancer/BreastCancer/DetailedGuide/breast-cancer-survival-by-stage