What are the stages of colorectal cancer?
What are the stages of colorectal cancer?
Colorectal cancer is described clinically by the stages at which it is discovered. The various stages of a colorectal cancer are determined by the depth of invasion through the wall of the intestine; the involvement of the lymph nodes (the drainage nodules); and the spread to other organs (metastases). Listed below is a description of the stages of colorectal cancer and the treatment for each stage. In most cases, treatment requires surgical removal (resection) of the affected part of the intestine. For some tumors, chemotherapy or — for rectal cancers — radiation are added to manage the disease.
Stage 0: For lesions that are stage 0 — also known as carcinoma in situ — the disease remains within the lining of the colon or rectum. Lesions are in the pre-cancerous stage and are not cancers. Therefore, removal of the lesion, either by polypectomy via colonoscopy or by surgery if the lesion is too large, may be all that is required for treatment.
Stage I: Stage I colorectal cancers have grown into the wall of the intestine but have not spread beyond its muscular coat or into close lymph nodes. The standard treatment of a stage I colon cancer is usually a colon resection alone, in which the affected part of the colon and its lymph nodes are removed. The type of surgery used to treat a rectal cancer is dependent upon its location, but includes a low anterior resection or an abdominoperineal resection.
Stage II: Stage II is divided into three smaller stages. In the first stage, IIA, the cancer has spread through the wall of the colon. In stage IIB, colorectal cancer has penetrated beyond the muscular layers of the large intestine. By stage IIC the cancer has even spread into adjacent tissue. However, in all stage II lesions, the cancer has not yet reached the lymph nodes. Usually the only treatment for this stage of colon cancer is a surgical resection (removal), although chemotherapy after surgery may be added. For a stage II rectal cancer, a surgical resection is sometimes preceded or followed by chemotherapy and/or radiation.
Stage III: A stage III colorectal cancer is considered an advanced stage of cancer as the disease has spread to the lymph nodes. Once again, there are three smaller stages of stage III colorectal cancer. Stage IIIA is characterized by cancer that has moved beyond the colon wall and spread to one to three lymph nodes or a very early lesion in the colon wall that has spread to four to six lymph nodes. In the second stage, IIIB, more lymph nodes are affected or there is a more advanced lesion in the colon wall with one to three lymph nodes affected. The cancer also impacts the organs in the abdomen in this stage. In stage IIIC, the cancer continues to spread to nearby lymph nodes and impacts more adjacent tissue of organs in the abdomen. For a colon cancer, surgery is usually done first, followed by chemotherapy. Chemotherapy and radiation may precede or follow surgery for a stage III rectal cancer.
Stage IV: For patients with stage IV colorectal cancer, the disease has spread (metastasized) to distant organs such as the liver, lungs or ovaries. This stage is also divided into three stages. Stage IVA is characterized by cancer that has spread to an organ and lymph nodes that are farther from the colon. In stage IVB the cancer has moved to more than one distant organ and more lymph nodes. Stage IVC cancer has impacted not only the distant organs and lymph nodes, but also the tissue of the abdomen. When the cancer has reached this stage, surgery is generally used for relieving or preventing complications as opposed to curing the patient of the disease. Occasionally the cancer's spread is restricted enough to where it can all be removed by surgery. In the case of minimal disease in the liver, the tumor may be treated with radiofrequency ablation (destruction with heat), cryotherapy (destruction by freezing), or intra-arterial chemotherapy. For stage IV cancer that cannot be surgically removed, chemotherapy, radiation therapy, or both may be used to relieve, delay, or prevent symptoms.