The American Cancer Society reports that cancer staging is a process during which doctors will attempt to determine if a cancer has spread and, if so, how far. Breast cancer stages range from stage 0 to stage IV. Each stage signifies something different, and recognition of what each stage indicates can make it easier for women to understand their disease.
Stage 0 The Memorial Sloan Kettering Cancer Center notes that when a woman is diagnosed with stage 0 breast cancer, that means abnormal cells are present but have not spread to nearby tissue. The National Breast Cancer Foundation, Inc. indicates stage 0 breast cancer is the earliest stage of the disease and is highly treatable when detected early. Indeed, the American Cancer Society reports a five-year survival rate of 99 percent among individuals diagnosed with stage 0 breast cancer.
Stage I Stage I is still considered early stage breast cancer. The MSKCC notes a stage I diagnosis indicates tumor cells have spread to normal surrounding breast tissue but are still contained in a small area. Stage I breast cancer may be characterized as stage IA, which indicates a tumor is about as large as a grape and cancer has not spread to the lymph nodes, or stage IB, which indicates the tumor may be slightly smaller but is accompanied by small clusters of cancer cells in the lymph nodes or there is no tumor and only the small clusters in the lymph nodes. The ACS also reports a 99 percent five-year survival rate for patients diagnosed with stage I breast cancer.
Stage II A stage II breast cancer diagnosis indicates the tumor is at least 20 millimeters (about the size of a stage IA tumor) and potentially as large as 50 millimeters. The tumor also can be larger than 50 millimeters if no lymph nodes are affected (stage IIB). The ACS notes the size of the tumor may indicate if the cancer is stage IIA or stage II B. The MSKCC notes that a stage IIA diagnosis could indicate there is no tumor or there is a tumor up to 20 millimeters and the cancer has spread to the lymph nodes under the arm. A tumor determined to be between 20 and 50 millimeters that has not spread to the lymph nodes also indicates a stage IIA diagnosis. A stage IIB diagnosis indicates the tumor in the breast is between 20 and 50 millimeters and has spread to between one and three nearby lymph nodes. According to Cancer Research UK, the five-year survival rate for stage II breast cancer is around 90 percent.
Stage III Stage III breast cancer is considered regional, which the ACS reports notes had a roughly 86 percent survival rate between 2013 and 2019. The MSKCC notes that a stage III diagnosis indicates the tumor is larger than 50 millimeters and has affected lymph nodes across a wider region than in less developed stages of the disease. Cancers that have reached stage III may be categorized as stage IIIA, stage IIIB or stage IIIC. The American College of Surgeons reports that stage IIIA indicates a tumor of any size that has spread to between four and nine lymph nodes or a tumor larger than five centimeters that has spread to between one and three lymph nodes. Stage IIIB indicates any size tumor and that the cancer has spready to the chest wall. A stage IIIC diagnosis indicates the tumor can be any size and has spread to 10 or more lymph nodes.
Stage IV Stage IV is the most advanced form of breast cancer. If the cancer has reached stage IV, that indicates the tumor can be any size and has spread beyond the breast to other parts of the body, potentially including organs and tissues. The ACS reports that survival rate for this stage, which is considered distant, is 31 percent. However, the breast cancer advocacy organization Susan G. Komen notes that only around 6 percent of breast cancer diagnoses in women diagnosed for the first time have reached stage IV at the time of diagnosis.
Staging makes it easier to understand a breast cancer diagnosis. More information about breast cancer staging is available at mskcc.org and cancer.org.
