Chemotherapy for colorectal cancer

Chemotherapy uses anticancer (cytotoxic) drugs to destroy cancer cells. It is sometimes used to treat colorectal cancer. Your healthcare team will consider your personal needs to plan the drugs, doses and schedules of chemotherapy. You may also receive other treatments.

Chemotherapy is often combined with radiation therapy to treat rectal cancer. This is called chemoradiation. The 2 treatments are given during the same time period.

Chemotherapy is given for different reasons. You may have chemotherapy or chemoradiation to:

• destroy cancer cells in the body
• shrink a tumour before other treatments such as surgery (called neoadjuvant chemotherapy)
• destroy cancer cells left behind after surgery and reduce the risk that the cancer will come back (recur) (called adjuvant chemotherapy)
• relieve pain or control the symptoms of advanced colorectal cancer (called palliative chemotherapy)

Chemotherapy is usually a systemic therapy. This means that the drugs travel through the bloodstream to reach and destroy cancer cells all over the body, including those that may have broken away from the primary tumour in the colon or rectum. Chemotherapy may also be a regional therapy, which means that it is given to a specific area of the body.

The most common chemotherapy drugs used to treat colorectal cancer are:

• 5-fluorouracil (Adrucil, 5-FU)
• capecitabine (Xeloda)
• oxaliplatin (Eloxatin)
• irinotecan (Camptosar)
• raltitrexed (Tomudex)
• trifluridine and tipiracil (Lonsurf)

Leucovorin (folinic acid) is a common drug used in treating colorectal cancer. It is not a chemotherapy drug but it helps 5-fluorouracil work better.

The most common chemotherapy drug combinations used to treat colorectal cancer are:

• 5-fluorouracil with leucovorin
• FOLFOX – leucovorin, 5-fluorouracil and oxaliplatin
• CAPOX (also called XELOX) – capecitabine and oxaliplatin
• FOLFIRI – leucovorin, 5-fluorouracil and irinotecan
• FOLFOXIRI – leucovorin, 5-fluorouracil, oxaliplatin, irinotecan
• CAPIRI – capecitabine and irinotecan

If colorectal cancer does not respond to drugs used in earlier treatments or if it comes back, the following drugs may be used:

• raltitrexed
• trifluridine and tipiracil

If colorectal cancer doesn’t respond to these drugs or if it recurs, you may be offered targeted therapy. A targeted therapy drug may be given along with chemotherapy.

A combination of nivolumab (Opdivo) and ipilimumab (Yervoy) may be offered if colorectal cancer has specific genetic characteristics and you were given either 5-fluorouracil or capecitabine in combination with oxaliplatin or irinotecan. Nivolumab and ipilimumab are drugs used in immunotherapy.

For chemoradiation, the chemotherapy drugs that are usually given are 5-fluorouracil or capecitabine.

Hepatic arterial infusion may be used to treat liver metastases when cancer has only spread to the liver and it can’t be removed with surgery. It delivers chemotherapy directly to liver tumours through the main artery of the liver (called the hepatic artery). Floxuridine (FUDR) is the most common chemotherapy drug used for hepatic arterial infusion.

Side effects can happen with any type of treatment for colorectal cancer, but everyone’s experience is different. Some people have many side effects. Other people have only a few side effects.

Chemotherapy may cause side effects because it can damage healthy cells as it kills cancer cells. If you develop side effects, they can happen any time during, immediately after or a few days or weeks after chemotherapy. Sometimes late side effects develop months or years after chemotherapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.

Side effects of chemotherapy will depend mainly on the type of drug, the dose, how it’s given, the effects of other treatments and your overall health. Side effects of chemoradiation can be more severe than those of chemotherapy alone.

Some common side effects of chemotherapy drugs used for colorectal cancer are:

• low blood cell counts
• fatigue
• diarrhea
• constipation
• sore mouth and throat
• nausea and vomiting
• loss of appetite
• hair loss
• skin problems
• nervous system problems

Tell your healthcare team if you have these side effects or others you think might be from chemotherapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Details on specific drugs change regularly. Find out more about sources of drug information and where to get details on specific drugs.

Find out more about chemotherapy and side effects of chemotherapy. To make the decisions that are right for you, ask your healthcare team questions about chemotherapy.