There are three main treatment options for colorectal cancer:

• Surgery removes cancer cells
• Chemotherapy kills cancer cells
• Radiation therapy destroys cancerous tissue
  

The choice of treatment depends in part on the stage of the cancer.

Surgery
Surgery (colectomy) is the main treatment for colorectal cancer. Stage 0 colon cancer may be treated by removing the cancer cells, often during a colonoscopy. In stages I, II, and III cancer, the affected part of the colon is removed surgically. The surgeon may perform a resection, consisting of a partial colectomy (removing the cancer and a small amount of healthy tissue around it) and an anastomosis (sewing the parts of the colon back together). Nearby lymph nodes may also be removed and biopsied.

If a resection isn't possible, for instance, if the cancer is at the outlet of the rectum, a colostomy may be performed. In a colostomy, an opening is created in the abdomen so that the remaining bowel can empty waste into a special bag. The colostomy may be temporary in order to allow the colon or rectum time to heal after surgery, or it may be permanent.

Where cancer has spread only to the liver, surgery may be performed to remove the cancerous lesion from the liver. Chemotherapy may be used before or after this type of surgery.

Patients with very advanced cancer may have palliative surgery. The goal of palliative surgery isn't to cure the cancer but to relieve its symptoms, such as bleeding and pain.

Complications of colorectal cancer surgery include short-term pain and tenderness, constipation, and diarrhea.

Chemotherapy
Although the majority of patients have the entire cancerous tumor removed by surgery, 50-60% will have a recurrence of cancer without further treatment. Chemotherapy may be given after surgery to lessen the chance of recurrence. The drugs used in chemotherapy destroy cancer cells, either by killing the cells or by preventing them from dividing.

Whether patients with stage II colon cancer should receive chemotherapy after surgery is controversial, as some studies have shown only a very small benefit in doing so. Most patients with stage III colon cancer should receive chemotherapy after surgery.

Chemotherapy may also be used palliatively to relieve symptoms of cancer. At the time of diagnosis of colorectal cancer, about 20% of patients have stage IV (metastatic) cancer, which is not considered curable. However, patients can have improved quality of life and survive longer with chemotherapy, although the average survival is still only 20 months.

Chemotherapy may be administered in three different ways:

• Systemic chemotherapy: intravenous. Drugs are injected into a vein or muscle, enter the bloodstream, and reach cancer cells throughout the body.
• Systemic chemotherapy: oral. Drugs are taken orally. As with intravenous administration, the drugs enter the bloodstream and reach cancer cells throughout the body.
• Regional chemotherapy. The drug is placed directly into a specific area of the body, such as the liver.

Possible side effects of chemotherapy include nausea and vomiting, mouth sores, fatigue, hair loss, and diarrhea.

Radiation
Radiation therapy uses powerful forms of energy, such as X-rays, to kill any cancer cells that may remain after surgery, to shrink large tumors so that they can be more easily removed surgically, or to relieve symptoms.

Colon cancer is rarely treated with radiation therapy, because radiation is a local treatment and is typically aimed at a target zone. A defined target zone can be difficult to determine after surgical resection. However, radiation therapy may be used to treat colon cancer when the cancer is difficult to remove because it has attached to an internal organ or the lining of the abdomen. Radiation may then be used in an attempt to eradicate any cancer cells that remain after surgery. Metastatic colon cancer is seldom treated with radiation therapy.

There is more of a role for radiation therapy in rectal cancer. Radiation may be given as adjuvant therapy along with chemotherapy to prevent recurrence of the cancer in the pelvis. It can be given either before or after surgery. Some physicians use radiation before surgery to shrink the tumor and make its removal easier. Giving radiation before surgery may lower the risk that cancer will recur in the pelvis, and may result in fewer complications, such as the formation of scar tissue that can interfere with bowel movements.

Radiation therapy can be used to help control rectal cancer growth for people who aren't healthy enough for surgery. It may also be used palliatively to control symptoms in people with advanced cancer that is causing symptoms such as intestinal blockage, bleeding, or pain.

More on this topic

Colorectal Cancer Screening (VIDEO)
Colorectal Cancer
Colon Anatomy & Function
What Is Colorectal Cancer
Tumor Growth
Cancer Staging
Signs & Symptoms
Screening & Diagnosis
A Less Invasive Look
Treating Colorectal Cancer
Detecting Cancer Recurrence
Preventing Cancer

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