Immunotherapy and colorectal cancer

Immunotherapy works with both your immune system and laboratory-made substances to find and attack cancer cells.

female doctor with female patient

What is immunotherapy?

Cancer immunotherapy, also known as immuno-oncology, is a form of cancer treatment that uses the body’s own immune system to help prevent, control, and eliminate cancer. Immunotherapy is also known as biologic therapy. It is usually used to treat patients with advanced colorectal cancer.

Over the last few decades, immunotherapy has become an important part of treating certain types of cancer. New ways of working with the immune system are being discovered at a fast pace, and new treatments are being tested and approved quickly as well.

Ask the Expert: Immunotherapy 101

How does immunotherapy work?

Immunotherapy can help treat cancer in three ways:

  • Stops cancer cells from forming
  • Prevents cancer from spreading to other areas of the body
  • Helps the immune system destroy cancer cells

Immunotherapy works with the natural defenses of your immune system so that it can find and attack cancer cells.

It also uses substances made in a lab that are similar to substances made by your immune system. These substances coordinate with your immune system, which in turn destroys cancer cells.

female researcher using microscope

Who can be treated with immunotherapy?

Currently, immunotherapy is FDA approved for patients:

  • with stage IV colorectal cancer whose tumors have a biomarker called microsatellite instability (MSI-H)


  • whose cancer has continued to spread while on other standard chemotherapy.

There are also many trials underway to find other strategies for using immunotherapy in those tumors that are not MSI-H. If you are interested in joining a clinical trial, talk to your doctor about what may be available for your specific colorectal cancer.

woman in pain on bed

Are there side effects from immunotherapy?

Every treatment has the potential to cause some side effects. Some people may be more sensitive than others to a particular drug. It also depends on your other treatments, medications, vitamins, and herbal supplements.

Although rare, some life-threatening side effects can occur. Immunotherapy side effects may need to be managed differently than those due to standard chemotherapy. Discuss potential side effects with your doctor before beginning any new therapy.

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