Cancer stage is determined during the initial diagnosis and used to determine the ensuing treatment plan, according to the American Society of Clinical Oncology. Stage 0 cancers are cancers that remain localized and have the best prognosis, while stage 4 cancers are advanced or metastatic cancers with the worst prognoses.
Stage 0 cancers are sometimes referred to as cancers “in situ,” which means that the cancer has not begun to spread beyond its place of origin, notes the American Society of Clinical Oncology. Cancer at this stage is usually quite curable, and sometimes the entire tumor can be removed by surgery alone, since it has not begun to invade the surrounding tissues.
Stage 1 cancer is typically a small tumor that has not spread into lymph nodes or nearby tissue, reports the American Society of Clinical Oncology. At this stage, cancer is sometimes referred to as early stage cancer and is usually highly treatable.
Stage 2 and 3 cancer may have grown into the nearby tissue more deeply or even spread to the lymph nodes, notes the American Society of Clinical Oncology. Tumors at this stage are larger than at other stages, but they have not spread to other areas of the body.
Stage 4 cancer is advanced cancer that has spread to other organs or elsewhere in the body, according to the American Society of Clinical Oncology. Some stage 4 cancers are treatable, but usually require surgery, radiation or chemotherapy or a combination of two or more of these.