- In stage I, the cancer has spread through the mucosa of the colon wall into middle layers of tissue.
- Treatment for stage I involves resection of the tumor. The tumor may be removed along with part of the colon (colectomy).
- In stage IIA, the cancer has spread beyond the middle layers to the outer tissues of the colon or rectum. In stage IIB, the cancer has penetrated through the colon or rectum wall into nearby tissue or organs.
- Treatment for stage II cancer involves surgical resection. Chemotherapy after surgery (adjuvant chemotherapy) plus radiation is considered standard treatment for stage II rectal cancer, but is under debate for stage II colon cancer.
- In stage III, lymph nodes are involved but not distant sites. Stage IIIA and IIIB cancer has spread to as many as three lymph nodes. Stage IIIC cancer involves four or more lymph nodes.
- Treatment for stage III colon cancer involves surgery and adjuvant chemotherapy with the FOLFOX regimen (5-FU, leucovorin, oxaliplatin). For patients with stage III rectal cancer, treatment includes chemotherapy and radiation, either before or following surgery.
- Stage IV is metastasized cancer. The cancer has spread to nearby lymph nodes and to other organs of the body such as the liver or lungs.
- Treatment for stage IV cancer may sometimes include surgery. When cancer has spread, surgery to remove or bypass obstructions in the intestine may be performed. In these circumstances, surgery is considered palliative in that it may improve symptoms but will not lead to cure. In some cases, surgery may also be performed to remove tumors in areas that the cancer has spread, such as the liver, ovaries, or lung.
- Chemotherapy is standard treatment for metastasized cancer. In advanced colorectal cancer, chemotherapy is either given directly into the arteries of the liver when it is involved or intravenously (through a vein) with 5-FU and leucovorin. The targeted therapy biologic drug bevacizumab may also be added. Other alternative chemotherapy choices are capecitabine, or irinotecan combined with cetuximab. Radiation therapy may be used in place of chemotherapy or in combination with it. Studies indicate that chemotherapy offers only a modest improvement in survival, but may help reduce symptoms.
Colorectal cancer is among the most curable of cancers when it is caught in its early stages. The term "5-year survival" means that patients have lived at least 5 years since diagnosis. The 5-year survival rate for colon cancer diagnosed and treated at stage I is 74%. The rates fall to 37 - 67% for stage II, 28 - 73% for stage II, and 6% for stage IV. However, there are other factors, including the appearance of cancer cells under the microscope, that can contribute to a patient's prognosis.
Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.