Colorectal Cancer: Chemotherapy

What is chemotherapy?

Chemotherapy (chemo) uses strong medicines to treat cancer. The medicines are made to attack and kill cancer cells, which grow quickly. Some normal cells also grow quickly. Because of this, chemo can also harm those cells. This causes side effects.

When might chemotherapy be used for colorectal cancer? 

Not everyone with colorectal cancer needs chemotherapy. But it's part of treatment for many people. Whether you need chemo, the type of chemo you get, and how long you get it, depends on:

  • The kind of cancer you have (colon or rectal cancer)

  • The stage of the cancer (how much there is and if it has spread)

  • The goal of the treatment, such as to shrink a tumor before surgery or to ease symptoms caused by advanced cancer

  • Your age and overall health

  • Concerns you have about side effects

  • What treatments you have had in the past, if any

Your healthcare provider may suggest chemo in any of these cases:

  • After surgery. Chemo is sometimes used for colon cancer as an added treatment after surgery. This is called adjuvant treatment. The chemo is used to kill any cancer cells that may have been left behind or might spread to other parts of the body, but are too small to be seen on imaging tests. Adjuvant chemo can help lower the chance of cancer coming back (recurring).

  • As the main treatment. Chemo (often along with radiation) can be used as the main treatment for colon and rectal cancers. This is most common when the cancer can't be removed with surgery or has spread to many areas, or the person is too sick to have surgery.

  • Along with radiation therapy. Chemo is often given along with radiation when treating colon and rectal cancers. This is called chemoradiation. The chemo helps the radiation work better.

  • Before surgery. Neoadjuvant is the word used to describe treatments given before surgery. Neoadjuvant chemo can be used to help shrink a tumor so it's easier to remove. This is often done (along with radiation) for rectal cancer.

  • If cancer comes back after treatment. Chemo may be used if colon or rectal cancer comes back after initial treatment.

How is chemotherapy given for colorectal cancer?

Before treatment starts, you will meet with a medical oncologist. This is a healthcare provider who treats cancer with medicines. The healthcare provider will discuss your treatment choices with you and explain what you might expect. 

You may get chemo medicine in 1 of these ways: 

  • IV (intravenous). The medicine is put right into your blood through a vein. The medicine may drip in slowly over many hours or even days. Or it may be given more quickly over a few minutes. When chemo is given over days, people often go home with a small infusion pump. It's in a bag that looks like a waist pack. It's disconnected later. Chemo may also be given right into an artery leading to the tumor if the cancer has spread to another organ (like the liver). 

  • Oral. You swallow these medicines as pills. They're as strong as the chemo put into your blood, but can be taken at home.

Chemo is most often given as an outpatient treatment. That means that you get it at a hospital, clinic, or healthcare provider's office. You can go home the same day. In rare cases, you may need to stay in the hospital during treatment. This is called inpatient treatment. In either case, you'll be watched for any reactions during treatment.

Chemo is given in cycles over a period of time. This means you have treatment days followed by rest periods. Each period of treatment and rest is 1 cycle. You may need several cycles. Your healthcare provider will discuss your chemo schedule with you.

Healthcare provider caring for man having infusion treatment.

Types of chemotherapy medicine

The chemo medicines most often used for colorectal cancer include:

  • Fluorouracil (5-FU)

  • Capecitabine

  • Irinotecan

  • Oxaliplatin

  • Trifluridine and tipiracil

In most cases, 2 or 3 of these medicines are combined. They're often given along with other medicines called targeted therapies.

Chemotherapy side effects

Side effects of chemo depend on the type and amount of medicine you’re taking. They vary from person to person. Talk with your healthcare providers about what to expect. When your treatment has ended, most side effects often go away over time.

There are often ways to help control some of these side effects. Tell your healthcare providers about any side effects you have. They can help you manage them and keep them from getting worse.

Some common side effects from chemo for colorectal cancer include:

  • Diarrhea (common with many of these medicines)

  • Increased risk for infection

  • Nausea and vomiting

  • Mouth sores

  • Bleeding and bruising more easily

  • Extreme tiredness (fatigue)

 Some side effects are seen more often with certain chemo medicines. For instance:

  • Capecitabine and 5-FU can cause hand-foot syndrome. This causes redness, pain, and sometimes peeling, blisters, or open sores on the palms of the hands and soles of the feet.

  • Oxaliplatin can cause nerve damage. This can lead to pain, tingling, and numbness in the hands and feet (neuropathy). This nerve damage may be long-term. Oxaliplatin is also linked to intense, short-term sensitivity to cold. This can cause pain when swallowing or touching something cold. Because of its side effects, it is used in people with more advanced stages of colon cancer especially if it is in the lymph nodes.

Working with your healthcare team

It's important to know which chemo medicines you're taking. Write the names down and ask your healthcare team how they work and what side effects they might have.

Talk with your healthcare team about what signs to look for and when to call them. For instance, chemo can make you more likely to get infections. Make sure you know what number to call with questions. Ask if there is a different number for evenings, holidays, and weekends.

It may be helpful to keep a diary of your side effects. A written list will make it easier for you to remember your questions when you go to your appointments. It will also make it easier for you to work with your healthcare team to make a plan to manage your side effects.

Online Medical Reviewer: Jessica Gotwals RN BSN MPH
Online Medical Reviewer: Sabrina Felson MD
Online Medical Reviewer: Todd Gersten MD
Date Last Reviewed: 1/1/2023
© 2023 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.