The American Society of Clinical Oncology explains that the end stage of cancer is diagnosed when the cancer has spread to other parts of the body. This stage is also called stage 4, advanced or metastatic cancer.
The stages of cancer are used to determine treatment or surgery for the cancer and are identified by the TNM system used by doctors. Each type of cancer has a different system, but they all follow TNM. According to the American Society of Clinical Oncology, the letter "T" with a number describes the size and location of a tumor. Higher value numbers indicate larger tumors. The letter "N" with a number indicates if the cancer has been found in the lymph nodes. Finally, the letter "M" describes if the cancer has spread to other parts of the body. If the cancer has spread to other parts of the body, the cancer has reached stage 4.
For a common cancer, such as breast cancer, a tumor can be any size and spread to other organs of the body during stage 4. The American Society of Clinical Oncology states that 5 to 6 percent of the time, the spreading cancer is found during the initial diagnosis of breast cancer. Breast cancer can spread to the bones, lungs, brain, liver, other lymph nodes or the chest wall. Breastcancer.org lists surgery, radiation, chemotherapy, hormonal therapy and targeted therapy as possible treatments for stage 4 breast cancer.