Possible approaches to treating colorectal cancer depend largely on the stage of the disease and the patient’s age and general state of health. There are three standard treatments: surgery, radiation therapy and chemotherapy.

Surgical removal of the cancer is the most common treatment for colorectal cancer. A surgeon may perform one of the following procedures:

• Local excision. Removal of early-stage cancer without cutting into the abdomen. This can involve polypectomy, removal of a polyp during a colonoscopy. Local excision also may be performed through the anus if the lesions are small and close to the anus.
  
  
• Colectomy (also called resection). Removal of a larger cancer and a small amount of healthy tissue around it. The surgeon then performs anastomosis, which involves sewing the healthy parts of colon or rectum together, sewing the remaining colon to the rectum or sewing the remaining rectum to the anus.
  
  In some cases, laparoscopic surgery may be performed to remove colon cancer. This procedure involves only a few small incisions in the in the abdomen instead of a larger one. The surgery is completed using a lighted tube and special instruments inside the body. The recovery time is usually faster for laparoscopic procedures than traditional surgery. Some studies have shown that laparoscopic surgery may produce better long-term results than traditional surgery.
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• Colectomy and colostomy. Creation of an opening (stoma) through the lower abdomen to allow waste to exit the body. Colostomy is completed if anastomosis is not possible. In some cases, colostomy is temporary and reversed after the lower colon heals. Colostomy may be permanent if the entire lower colon is removed.
  
  
• Radiofrequency ablation. Use of a probe that has cancer-killing electrodes. Local anesthesia is used if the probe can be inserted through the skin. General anesthesia is used in a hospital if the probe must be inserted through an incision in the abdomen.
  
  
• Cryotherapy (cryosurgery). Use of an instrument that freezes and destroys abnormal growths. Ablation and cryotherapy are not generally useful for the primary tumor.

Radiation therapy may be used to treat the disease, either before or after surgery. This treatment uses precise high energy x-rays to kill or shrink cancer cells.  It may be performed to reduce large tumors before surgery or to kill any cancer cells left after surgery. In advanced cases of colorectal cancer, radiation may be used to reduce pain, intestinal blockage or other symptoms. Side effects of radiation used on colorectal cancer are often temporary. They include sexual problems, diarrhea, nausea and fatigue. Types of radiation include:

• External beam radiation therapy. Radiation is emitted by a machine outside the body to destroy cancer cells in a targeted, focused area.
  
  
• Endocavitary radiation therapy. This is similar to external beam but has the advantage of being aimed through the anus to the rectum, thus avoiding the abdominal tissues.
  
  
• Brachytherapy (internal radiation therapy). Small radioactive pellets are placed into or next to the cancer. This may be used in people with rectal cancer who cannot tolerate surgery.

Chemotherapy is the use of powerful drugs to kill or control cancer cells. It may be used for the same reasons as radiation therapy, including reducing cancer before surgery or destroying cancer cells that remain after surgery. In addition, chemotherapy is used to treat the entire body when cancer has spread to tissues and organs. Chemotherapy may be combined with radiation therapy in treatment. It may also be used as adjuvant or prophylactic therapy when there is no evidence of cancer but there is a risk of recurrence.

Researchers are testing other approaches for colorectal cancer treatment in clinical trials not available to the general patient population. This includes biological therapy, which uses the patient’s immune system to fight cancer as well as certain methods that directly attack the cancer.  New drugs are also being used that target human growth factors. Growth factors are substances in the body that help tumors grow. Certain drugs are being tested in clinical trials that can spot these factors and neutralize them, thereby helping prevent cancer cells from growing and spreading. Another drug (bevacizumab) that interferes with the formation of blood vessels that nourish a tumor has also been approved to treat colorectal cancer.