About colorectal cancer

Chemotherapy for Colorectal Cancer

two physicians administering chemotherapy to a patient
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What is chemotherapy?  

Chemotherapy is treatment with medications that kill cancer cells. Chemotherapy drugs stop or slow the growth of tumors by destroying cancer cells.  

On this page, the term chemotherapy (or chemo) is used to refer to conventional anti-cancer drugs only. These are sometimes called cytotoxic drugs. For information about cancer treatment with immunotherapy drugs and targeted therapy drugs, see Immunotherapy and Targeted Therapy.

What are my chemotherapy treatment options for colorectal cancer?  

Your oncology team will choose your chemotherapy medications and doses based on features of your cancer and your general health. Typically, if your colorectal cancer is stage I, you will not need chemotherapy. If your CRC is stage II, your team will look at characteristics of your cancer associated with a risk of recurrence to decide if chemotherapy is needed. These features include the cancer grade (how abnormal the cancer cells look under a microscope), whether your cancer has entered blood vessels or lymph vessels, whether your surgeon has been able to remove 12 lymph nodes to examine for cancer spread, and whether the margins around the removed tumor are clear of cancer. If you have advanced colorectal cancer (stage III or stage IV), it is very likely that you will have chemotherapy.  

What types of chemotherapy are used to treat colorectal cancer?  

The anti-cancer drugs used to treat CRC include:

  • 5-Fluorouracil (5-FU)
  • Capecitabine (Xeloda)
  • Irinotecan hydrochloride (Camptosar)
  • Folinic acid, also known as leucovorin, leucovorin calcium, or calcium folinate
  • Oxaliplatin (Eloxatin)
  • Trifluridine and tipiracil Hydrochloride (Lonsurf)

Often, chemotherapy drugs are used in combinations such as:

  • FOLFOX regimen: folinic acid/leucovorin + fluorouracil/5-FU + oxaliplatin  
  • FOLFIRI regimen: folinic acid/leucovorin + irinotecan  
  • FOLFOXIRI regimen: folinic acid/leucovorin + fluorouracil/5-FU + oxaliplatin + irinotecan
  • CAPOX regimen: capecitabine + oxaliplatin. Also known as CAPEOX regimen

Sometimes chemotherapy is given in combination with radiation therapy. This is called chemoradiation. Chemo drugs may also be used together with immunotherapy or targeted therapy drugs for colon cancer and rectal cancer. Targeted therapy and immunotherapy decisions are usually made based on the results of biomarker testing. Biomarker testing can also identify patients at higher risk of severe toxicity from certain chemotherapy drugs. Talk to your oncology team about biomarker testing and whether it could affect your treatment plan.

How are chemotherapy drugs given?

Most colorectal cancer chemotherapy drugs are given by injection, usually into a blood vessel. Some chemo drugs are given orally in a pill or liquid. Chemotherapy is given in an outpatient department of a hospital or cancer care center, a doctor's office or clinic, or at home. Rarely, a patient may need to stay overnight in the hospital for chemo treatment.

Chemotherapy that is given before the main colon cancer or rectal cancer treatment, such as surgery, is called neoadjuvant chemotherapy. When chemo drugs are given after the main cancer treatment of surgery, it is called adjuvant chemotherapy.

Chemotherapy is a systemic treatment, which means it travels through the bloodstream to reach cancer cells in all parts of the body. There are some cases where chemotherapy is given regionally, to target a specific area of the body and limiting the amount that circulates systemically. One example is hepatic arterial infusion, where chemo is directed to the liver through the hepatic (liver) artery. It is used in cases of liver metastasis. Another regional chemotherapy treatment is hyperthermic intraperitoneal chemotherapy (HIPEC). HIPEC involves infusing and circulating a heated chemotherapy drug solution in the abdominal cavity, either laparoscopically or during open surgery. The heat and the chemotherapy work together to destroy cancer cells on the peritoneum (the lining of the abdominal cavity) and on the surfaces of other organs. HIPEC is used in cases when colorectal cancer has spread to the peritoneum (peritoneal metastasis).  

What are the side effects of chemotherapy for colorectal cancer?  

The side effects of chemotherapy depend on which drug or drug combination you are taking, as well as what dose you are taking.  

Chemotherapy drugs affect cells that divide quickly, and cancer cells are rapidly dividing so they are affected. But some healthy cells also divide quickly, and when those are affected by chemotherapy drugs, side effects may occur.

The most common side effects of chemotherapy for colorectal cancer are hair loss, mouth sores, decreased appetite and weight loss, nausea and vomiting, diarrhea, and skin and nail changes.

Some drug side effects can also depend on your genes. If you have a genetic change (mutation) that affects the way your body metabolizes certain drugs, it can increase your risk of severe side effects. For example, mutations in the DPYD gene can affect the metabolism and side effects of 5-fluorouracil, and mutations in the UGT1A1 gene may affect irinotecan metabolism and side effects. Testing for these mutations before chemotherapy may prevent some cases of severe toxicity.  

Be sure to tell your healthcare team about any side effects you experience.

The goal is that chemotherapy side effects will go away after treatment is completed, and many do go away or at least get better. However, some may last beyond treatment, such as chemotherapy-induced neuropathy. Neuropathy is more common with use of oxaliplatin, and is characterized by pain, numbness, and tingling in the hands and feet.

For more information about chemotherapy, including a comprehensive look at side effects and tips for managing them, the National Cancer Institute has published a free book for cancer patients called Chemotherapy and You. It is available for download as a PDF or Kindle e-book and can be ordered in print for free.

Next article: Radiation for Colorectal Cancer
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