What Is Immunotherapy and How Does It Work Against Cancer?

How Immunotherapy Treatment Helps the Immune System Recognize Cancer Cells

pill in elderly person's hand
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Immunotherapy is a therapy used in treating cancer. Compared to other cancer treatment options, immunotherapy is still considered new and has been found to treat some cancers more effectively when combined with other types of cancer treatment (therefore it is often used in conjunction with chemotherapy or radiation treatment).

There are different types of immunotherapy which work better for some types of cancer than others.

Some immunotherapy treatments work to boost simply boost the body’s own immune system while others help the immune system learn how to attack specific cancer cells. Immunotherapy is also used to lessen the side effects of chemotherapy or radiation.

What Exactly Is Immunotherapy?

Immunotherapy stimulates a person's own immune system to help fight diseases (such as cancer). This can be accomplished by using a cancer vaccine, antibody therapy, or non-specific immunotherapies in the following ways:

  • By stimulating the body's own immune system to become stronger and better at recognizing cancer cells in order to attack them.
  • By adding components of the immune system (such as man-made immune system proteins) to the body when the body has a weak immune system or is lacking sufficient components.

Depending on the type of immunotherapy, your doctor or oncologist may also refer to your immunotherapy treatment as biologic therapy or biotherapy.

How the Immune System Is Affected

A healthy immune system is made up of organs, special cells, proteins and other substances that help protect you from infections and disease. By keeping track of all of the substances normally found in your body, your immune system knows if there are any foreign substances (such as germs, viruses or parasites, known as antigens) that enter your body.

The body's immune system reacts to these unknown substances and when an antigen is found, the response of the immune system is to kill the antigen and anything it may be attached to.

Unfortunately even a healthy immune system can have a hard time distinguishing between normal cells and cancerous cells. At times, cancer cells have an abnormal outer layer, similar to that of an antigen. By using immunotherapy, the immune system can be trained to be more effective in killing cancer cells.

In other instances, chemotherapy or radiation therapy is used to stop or slow down the growth of cancer cells, so that the cancer is prevented from spreading. The use of immunotherapy may then help to lessen the subsequent side effects of chemo or radiation.

The FDA has approved treatment of immunotherapy in the following cancers:

  • Melanoma
  • Leukemias, Lymphomas, and Myelomas
  • Kidney cancer
  • Prostate Cancer
  • Breast Cancer
  • Cervical Cancer
  • Ovarian Cancer
  • Colorectal Cancer
  • Lung Cancer

Immunotherapy can be given in a variety of ways—pill, IV, and injection.

How often you receive therapy depends on the type of cancer you have, and what stage it is in. Research in immunotherapy has been growing steadily in the last few decades and newer types of immunotherapy treatments are being studied. These new types of treatments may play a large part in how cancer is treated in the future.


American Cancer Society. What is cancer immunotherapy? Accessed 21 March 2016.

National Cancer Institute. Immunotherapy: Using the Immune System to Treat Cancer. Accessed 21 March 2016.

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