This page discusses the use of chemotherapy for the treatment of colorectal cancer. For a thorough review of chemotherapy for cancer treatment, please see the chemotherapy treatment monograph .

Chemotherapy uses drugs to kill cancer cells. In order to attack cancer cells that may have traveled to other parts of the body, the drugs work systemically—entering through the bloodstream and traveling throughout the body—to kill cancer cells. Chemotherapy may be given either alone or along with radiation therapy. When given alone it is given in a higher dose designed to kill off cancer cells. When given along with radiation therapy it is delivered at a lower dose, and is designed to make the cancer more sensitive to the radiation. Chemotherapy is usually given by vein, but some forms can be given by mouth as well. Your medical oncologist will tell you how many cycles or courses of chemotherapy are best for you.

There is some debate about how many cycles of chemotherapy are used in the treatment of colon and rectal cancer. Generally, when patients get chemotherapy alone for colon or rectal cancer (after surgery ), they receive between 6 to 12 cycles. When it is given along with radiation therapy , the patient may get two cycles alone, and then two more cycles with the radiation therapy, and then another two to eight cycles after the radiation therapy is done. Different schedules are used by different oncologists, and you should discuss your exact plan with your doctor

Chemotherapy Drugs Used for Colorectal Cancer

Most colorectal cancer regimens combine one or more chemotherapy drugs together to create a stronger attack on cancer cells. The most commonly used drugs include:

  • Leucovorin
  • Irinotecan

Recently, two new drugs have been approved for patients with advanced stage colon cancer:

  • Camptosar
  • Eloxatin

Side Effects and Possible Complications

Most chemotherapy does result in certain long- and/or short-term side effects, which are caused by the destruction of normal cells in addition to cancer cells. The side effects and amount of time required in the doctor’s office will depend on the type of chemotherapy you receive, as well as how many cycles you receive and how often.

The most common chemotherapy-associated side effects are:

  • Nausea and vomiting
  • Fatigue or tiredness
  • Decreased blood counts
  • Sores inside the mouth
  • Numbness in the hands and feet
  • Diarrhea, loose-stool
  • Increased urgency to have a bowel movement or urinate

When chemotherapy is given at a lower dose, as when it is given along with radiation, these side effects are less common. However, most people still feel fatigued.

Medications may help to prevent or reduce side effects of treatment, or to manage certain side effects once they occur. You can develop side effects from the treatment and/or from the cancer itself. Tell your doctor when you notice a new symptom, and ask him or her if any of these medications are appropriate for you.

For more information on chemotherapy including how to manage side effects, see the chemotherapy treatment monograph .