After a diagnosis of breast cancer is made, the next step is staging the disease. Staging is a standardized way of describing the extent and spread of the cancer, and helps to guide treatment and prognosis. The tumor size, lymph node involvement, and whether or not the cancer has metastasized, or spread to distant organs, all help to determine whether breast cancer is in early or late stages.
Stage 0 (DCIS)
Stage 0 breast cancer is the earliest form of breast cancer, also referred to as "ductal carcinoma in situ," or DCIS, in this stage. The cancer cells are confined to a duct and have not spread into breast tissue; it is noninvasive in this stage. According to the American Cancer Society, sometimes lobular carcinoma in situ (LCIS) is also diagnosed as Stage 0 breast cancer, but most oncologists do not consider LCIS a true cancer. Paget's disease of the nipple is also classified as Stage 0 if there is no breast tumor.
Stage I
Stage I breast cancer can be divided into two sub-stages, Stage IA and IB. Stage IA consists of breast tumors that are 2cm or less and there are no cancerous lymph nodes. In Stage IB, the tumor is not only 2cm or less, but micrometastases are found in one to three lymph nodes under the arm. There is no cancer in any distant organs in Stage I breast cancer.
Stage II
Stage II breast cancer also has two sub-stages. In Stage IIA, there may be several situations: No tumor is found in the breast, but breast cancer has been found in underarm lymph nodes; the breast tumor is 2cm or less and cancer is in the underarm lymph nodes; or the tumor is between 2cm and 5cm but there is no cancer in the lymph nodes. Stage IIB consists of breast cancer that is either between 2 and 5cm and has also been found in the underarm lymph nodes, or a tumor that is more than 5cm without any cancer in the lymph nodes. In Stage II breast cancer, the cancer has not spread to any other organs.
