There is an international standard for breast cancer and all cancers called the TNM staging system. TNM refers to the malignancy of a tumor based on a list of factors involving the tumor (T), node (N), and metastases (M). When staging, the factors that are considered are how big the tumor is, and whether it has spread to surrounding tissues. Another factor is whether the cancer has spread to lymph nodes, or other body parts. In terms of surface area covered by the cancer, stage zero is the smallest and stage four is the largest. Even having the largest, most advanced stage of cancer does not necessarily mean the cancer is not curable. In all stages, your doctor will talk with you about your treatment options.