Skip to main content

How Does Immunotherapy Work?

Immunotherapy is a type of cancer treatment that uses the body’s natural defenses (the immune system) to identify, attack, and kill cancer cells.

The immune system’s purpose is to attack any cell that it sees as unhealthy or abnormal. Cancer cells can hide from these defenses or even stop an attack. New knowledge about the complex interactions between the immune system and cancer is leading to new treatments. Although there are promising results, immunotherapy does not work for every cancer type or every patient. There is still a lot that researchers don’t know.

Types of Immunotherapy

Most immunotherapies today are biologic therapies— made by living organisms. There are many types in development. They help fight cancer by:

  • Boosting the immune system. A "revved up" immune system can fight cancer better.
  • "Marking" cancer cells so that your immune system can find and destroy them. This keeps the cancer from being able to hide.
  • Helping the immune system find cancer cells and deliver treatment (like chemotherapy, radiation, or even T cells) directly to the cancer cells.

There is broad interest and excitement about the potential for immunotherapy to treat many kinds of cancer. As researchers learn more about how the immune system interacts with cancer, they will be able to apply that knowledge to more cancer types

Current Immunotherapies by Cancer Type

Eligibility & Side Effects

Dr. G: Immunotherapy Side Effects

Dr. G: Immunotherapy Side Effects


Who Is Eligible for Immunotherapy?

  • People with cancers that are advanced (metastatic, or stage 4).
  • People with cancers that have returned and spread after initial treatment or were diagnosed in an advanced stage.
  • Researchers are hosting new clinical trials for people with earlier-stage cancers who are at high risk for having their cancers return or spread.
  • Some people cannot recieve immunotherapy because of health problems (such as autoimmune disorders) that make it impossible to take these drugs safely.

Ask your health care team if immunotherapy could be helpful for you. Also ask about costs. These are expensive treatments and can be an issue for many patients. Fortunately, many centers have resources to help patients get insurance coverage or access financial programs that can help.

Possible Side Effects

We tend to think of immunotherapy as “natural”—as a stronger version of our body’s own defense system. However, immunotherapy can still have side effects. In many cases, they are minor and may be short-lived or easy to manage. Less often, they are severe and may even be life-threatening. Little is known about whether there are long-term side effects.

The side effects listed here are seen with checkpoint inhibitor immunotherapy drugs.

Common side effects:

  • Flu-like symptoms (fever, chills, headache, nausea, cough, loss of appetite)
  • Fatigue (some people get extreme fatigue)
  • Rashes, redness, or itching
  • Pain or soreness
  • Muscle or joint pain
  • Drops in blood pressure

Less common side effects:

  • Colitis or other gastrointestinal problems (stomach pain, diarrhea)
  • Thyroid problems
  • Lung problems (cough, shortness of breath)
  • Other serious autoimmune conditions (such as pituitary disorders or diabetes)

Most side effects can be treated early and managed well. Sometimes a side effect will occur several months later. Having one or more side effect does not always mean that you must stop taking drugs that are working for you.

If you are on immunotherapy, it is important to let your health care team know right away if you notice any change in how you feel.

Watch More Videos

Immunotherapy Webinars

Most people who receive immunotherapy today have cancers that are advanced. Their cancers have either recurred and spread after primary treatment, or were diagnosed with advanced stage cancers. At this time, most immunotherapy is still given in specialized cancer centers and mostly as part of a clinical trial. The Cancer Support Community recently hosted three webinars on the topic of immunotherapy:

Clinical Trials & Immunotherapy

What is New with Immunotherapy

Immunotherapy & Side Effects


Understanding Immunotherapy

Are you on an immunotherapy? It seems like a simple question, but there is actually a lot of confusion about what immunotherapy is and how it works.

New Video Explains Immunotherapy Treatment Options for Non-small Cell Lung Cancer (NSCLC)

What is cancer immunotherapy? How does immunotherapy work to control cancer? Should I consider participating in a cancer immunotherapy clinical trial?

What President Carter’s Announcement Teaches Us about Immunotherapy

This week, President Jimmy Carter announced he has been declared N.E.D (No Evidence of Disease) after undergoing treatment for metastatic melanoma, which was diagnosed in August of this year. President Carter credits this happy announcement to an immunotherapy treatment he received. Immunotherapy is a type of cancer treatment that uses the body’s own immune system to control cancer.  Here’s what we know about this exciting new treatment option and how it works.