user: What are the treatments for Colorectal Cancer ?

assistant: Treatments are available for all patients who have colon cancer. The choice of treatment depends on the size, location, and stage of the cancer and on the patient's general health. Doctors may suggest several treatments or combinations of treatments. Surgery Is the Most Common First Step in a Treatment Regimen The three standard treatments for colon cancer are surgery, chemotherapy, and radiation. Surgery, however, is the most common first step in the treatment for all stages of colon cancer. Surgery is an operation to remove the cancer. A doctor may remove the cancer using several types of surgery. Local Excision If the cancer is found at a very early stage, the doctor may remove it without cutting through the abdominal wall. Instead, the doctor may put a tube up the rectum into the colon and cut the cancer out. This is called a local excision. If the cancer is found in a polyp, which is a small bulging piece of tissue, the operation is called a polypectomy. Colectomy If the cancer is larger, the surgeon will remove the cancer and a small amount of healthy tissue around it. This is called a colectomy. The surgeon may then sew the healthy parts of the colon together. Usually, the surgeon will also remove lymph nodes near the colon and examine them under a microscope to see whether they contain cancer. Colostomy If the doctor is not able to sew the two ends of the colon back together, an opening called a stoma is made on the abdomen for waste to pass out of the body before it reaches the rectum. This procedure is called a colostomy. Sometimes the colostomy is needed only until the lower colon has healed, and then it can be reversed. But if the doctor needs to remove the entire lower colon or rectum, the colostomy may be permanent. Adjuvant Chemotherapy Even if the doctor removes all of the cancer that can be seen at the time of the operation, many patients receive chemotherapy after surgery to kill any cancer cells that are left. Chemotherapy treatment after surgery -- to increase the chances of a cure -- is called adjuvant therapy. Researchers have found that patients who received adjuvant therapy usually survived longer and went for longer periods of time without a recurrence of colon cancer than patients treated with surgery alone. Patients age 70 and older benefited from adjuvant treatment as much as their younger counterparts. In fact, adjuvant therapy is equally as effective -- and no more toxic -- for patients 70 and older as it is for younger patients, provided the older patients have no other serious diseases. Adjuvant chemotherapy is standard treatment for patients whose cancer is operable and who are at high risk for a recurrence of the disease. Most cases of colon cancer occur in individuals age 65 and over. But studies have shown that older patients receive adjuvant chemotherapy less frequently than younger patients. Chemotherapy Chemotherapy is the use of anti-cancer drugs to kill cancer cells. Chemotherapy may be taken by mouth, or it may be put into the body by inserting a needle into a vein or muscle. One form of chemotherapy is called systemic treatment because the drugs enter the bloodstream, travel through the body, and can kill cancer cells throughout the body. The other form of chemotherapy is called targeted therapy because the drug affects only the factors that are causing the cancer and does not perturb the rest of the body. Radiation Therapy Radiation therapy is the use of x-rays or other types of radiation to kill cancer cells and shrink tumors. Most often, doctors use it for patients whose cancer is in the rectum. Doctors may use radiation before surgery to shrink a tumor in the rectum and make it easier to remove. Or, they may use it after surgery to destroy any cancer cells that remain in the treated area. The radiation may come from a machine or from implants placed directly into or near the tumor. Radiation that comes from a machine is called external radiation. Radiation that uses implants is known as internal radiation. Some patients have both kinds of therapy.