- After colon cancer has been diagnosed, tests are done to find out if cancer cells have spread within the colon or to other parts of the body.
- There are three ways that cancer spreads in the body.
- Cancer may spread from where it began to other parts of the body.
- The following stages are used for colon cancer:
Stage 0. For cancers that are stage 0—also known as carcinoma in situ—the disease remains within the lining of the colon or rectum. Therefore, removal of the cancer, either by polypectomy via colonoscopy or by surgery if the lesion is too large, may be all that is required for treatment.
Stage I colorectal cancers have grown into the wall of the intestine but have not spread beyond its muscular coat. 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, which are described in other patient information forms.
Stage II colorectal cancer has penetrated beyond the muscular layers of the large intestine (stage 2B) and even spread into adjacent tissue (stage 2C). However, it has not yet reached the lymph nodes. Usually the only treatment for this stage of colon cancer is a surgical resection, although chemotherapy after surgery may be added. For a stage 2 rectal cancer, a surgical resection is sometimes preceded or followed by chemotherapy and/or radiation.
Stage III, colorectal cancer is considered an advanced stage of cancer as the disease has spread to the lymph nodes. For a colon cancer, surgery is usually done first, followed by chemotherapy. Chemotherapy and radiation may precede or follow surgery for a stage 3 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. 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 4 cancer that cannot be surgically removed, chemotherapy, radiation therapy, or both may be used to relieve, delay, or prevent symptoms.