Chemotherapy for Colorectal Cancer

Chemotherapy (chemo) is often used to treat colorectal cancer. It's the use of drugs to kill cancer cells.

How is chemotherapy given?

You can get chemotherapy in different ways.

  • Systemic chemotherapy: Drugs are put right into your blood through a vein or you take them by mouth. The drugs enter your bloodstream and reach all areas of your body. This can help reduce the risk of colorectal cancer spreading to other parts of the body.
  • Regional chemotherapy: Drugs are put right into an artery that leads to the part of the body with the tumor. This focuses the chemo on the cancer cells in that area. It reduces side effects by limiting the amount of drug reaching the rest of your body. Hepatic artery infusion, or chemo given directly into the hepatic artery, is an example of regional chemotherapy sometimes used for cancer that has spread to the liver. 

Doctors give chemo in cycles, with each treatment followed by a rest period to give the body time to recover. Chemotherapy cycles generally last about 2 to 4 weeks. People usually get at least several cycles of treatment.

When is chemotherapy used for colorectal cancer?

Chemo may be used at different times during treatment for colorectal cancer:

  • Adjuvant chemo is given after surgery. The goal is to kill any cancer cells that might have been left behind at surgery because they were too small to see, as well as cancer cells that might have escaped from the main tumor and settled in other parts of the body but are too small to see on imaging tests. This helps lower the chance that the cancer will come back.
  • Neoadjuvant chemo is given (sometimes with radiation) before surgery to try to shrink the cancer and make it easier to remove. This is often done for rectal cancer.
  • For advanced cancers that have spread to other organs like the liver, chemo can be used to help shrink tumors and ease problems they're causing. While it's not likely to cure the cancer, this often helps people feel better and live longer.

Drugs used to treat colorectal cancer

Some drugs commonly used for colorectal cancer include:

  • 5-Fluorouracil (5-FU)
  • Capecitabine (Xeloda), which is in pill form. Once in the body, it is changed to 5-FU when it gets to the tumor site.
  • Irinotecan (Camptosar)
  • Oxaliplatin (Eloxatin)
  • Trifluridine and tipiracil (Lonsurf), a combination drug in pill form

In most cases, 2 or more of these drugs are combined, which makes them work better. Sometimes, chemo drugs are given along with a targeted therapy drug.

Side effects of chemo

Chemo drugs attack cells that are dividing quickly, which is why they work against cancer cells. But other cells in the body, such as those in the bone marrow (where new blood cells are made), the lining of the mouth and intestines, and the hair follicles, are also dividing quickly. These cells can be affected by chemo too, which can lead to side effects.

The side effects of chemo depend on the type and dose of drugs given and how long you take them. Common side effects of chemo can include:

  • Hair loss
  • Mouth sores
  • Loss of appetite
  • Nausea and vomiting
  • Diarrhea
  • Increased chance of infections (from having too few white blood cells)
  • Easy bruising or bleeding (from having too few blood platelets)
  • Fatigue (from having too few red blood cells)

Along with these, some side effects are specific to certain drugs. For example:

  • Hand-foot syndrome can develop during treatment with capecitabine or 5-FU (when given as an infusion). It can start out as redness in the hands and feet, and then progress to pain and sensitivity in the palms and soles. If it worsens, the skin may blister or peel, sometimes leading to painful sores. It’s important to tell your doctor right away about any early symptoms, such as redness or sensitivity, so that steps can be taken to keep things from getting worse.
  • Neuropathy (nerve damage) is a common side effect of oxaliplatin. Symptoms include numbness, tingling, and even pain in the hands and feet. It can also cause intense sensitivity to hot and cold in your throat, esophagus (the tube connecting the throat to the stomach), and the palms of your hands. This can cause pain when swallowing liquids or holding a cold glass. If you'll be getting oxaliplatin, talk with your doctor about side effects beforehand, and let him or her know right away if you develop numbness and tingling or other side effects.
  • Allergic or sensitivity reactions can happen in some people while getting the drug oxaliplatin. Symptoms can include skin rash; chest tightness and trouble breathing; back pain; or feeling dizzy, lightheaded, or weak. Be sure to tell your nurse right away if you notice any of these symptoms while you're getting chemo.
  • Diarrhea is a common side effect with many of these drugs, but can be particularly bad with irinotecan. It needs to be treated right away — at the first loose stool — to prevent severe dehydration. This often means taking a drug like loperamide (Imodium). If you're getting a chemo drug that will likely cause diarrhea, your doctor will give you instructions on what drugs to take and how often to take them to control this problem.

Most of these side effects tend to go away over time after treatment ends. Some, such as hand and foot numbness from oxaliplatin, may last for a long time. There are often ways to ease these side effects. For example, you can be given drugs to help prevent or reduce nausea and vomiting.

Be sure to discuss any questions about side effects with your cancer care team. Also report any side effects or changes you notice while getting chemo so that they can be treated right away. In some cases, the doses of the chemo drugs may need to be reduced or treatment may need to be delayed or stopped to help keep the problem from getting worse.

Older people seem to be able to tolerate some types of chemo for colorectal cancer fairly well. Age is no reason to withhold treatment in otherwise healthy people.

More information about chemotherapy

For more general information about how chemotherapy is used to treat cancer, see Chemotherapy.

To learn about some of the side effects listed here and how to manage them, see Managing Cancer-related Side Effects.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

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Last Medical Review: February 21, 2018 Last Revised: February 21, 2018

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