The short answer
Immunotherapy is treatment that helps your own immune system act against cancer. Targeted therapy uses drugs that target specific proteins that control how cancer cells grow, divide, and spread. They work in different ways, and some drugs can even overlap. Which one is used, if any, depends on your cancer and often on testing.
Immunotherapy helps your immune system find and fight cancer cells.
Targeted therapy targets specific proteins that control how cancer cells grow, divide, and spread.
Targeted therapy usually needs testing of your tumor first to see if it has a target for a drug.
The two overlap: some monoclonal antibodies are used in both immunotherapy and targeted therapy.
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The full explanation.
The short version
Both immunotherapy and targeted therapy are newer kinds of cancer treatment, and it is easy to mix them up. The difference is in what they act on:
- Immunotherapy helps your own immune system fight cancer.
- Targeted therapy targets specific proteins that control how cancer cells grow, divide, and spread.
One works through your body's defenses. The other goes after features of the cancer cells themselves.
How immunotherapy works
Your immune system normally detects and destroys abnormal cells, and it can slow or prevent the growth of many cancers. But cancer cells find ways to avoid it — for example, by making proteins that turn off immune cells. Immunotherapy helps the immune system act against the cancer more strongly. Types include immune checkpoint inhibitors, T-cell transfer therapy, monoclonal antibodies, treatment vaccines, and immune system modulators.
How targeted therapy works
Targeted therapy is the foundation of what is called precision medicine. As researchers learn more about the DNA changes and proteins that drive cancer, they can design drugs that interfere with those proteins. Targeted therapy can, for example, stop the signals that tell cancer cells to divide, block the forming of new blood vessels a tumor needs, or deliver cell-killing substances straight to cancer cells. This is different from chemotherapy, which often kills all cells that grow and divide quickly.
Where the two overlap
The line between the two is not always sharp. Monoclonal antibodies — lab-made proteins that attach to specific targets on cancer cells — are used in both. Some are described as immunotherapy because they mark cancer cells so the immune system can find them. Others are described as targeted therapy because they directly stop cancer cells from growing or carry toxins to them. So a single drug can fall into both groups.
Testing first
For targeted therapy, your tumor usually needs to be tested to see if it has a target that a drug can act on. This is called biomarker testing. For some cancers, such as one form of chronic myelogenous leukemia, nearly everyone with the cancer has the target, so testing may not be needed. Immunotherapy is approved for many cancers, but only some people respond, and researchers are working on ways to predict who will.
Side effects
Both treatments can cause side effects. Immunotherapy side effects often happen when the revved-up immune system also acts against healthy cells and tissues. Targeted therapy side effects commonly include diarrhea and liver problems, and can include high blood pressure, fatigue, and skin changes. Most side effects of targeted therapy go away after treatment ends.
The bottom line
Neither treatment is simply "better." They do different jobs, they are sometimes combined with each other or with chemotherapy and radiation, and not every cancer has a target for them. Ask your care team what is being considered for you, whether testing is needed, and what to expect.
Words to know
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Common questions
▸What is the main difference between immunotherapy and targeted therapy?
Immunotherapy helps your immune system act against cancer. Targeted therapy targets specific proteins that control how cancer cells grow, divide, and spread. One works through your body's defenses; the other goes after features of the cancer cells themselves.
▸Do I need testing before targeted therapy?
Often, yes. For most cancers, your tumor is tested to see if it has a target that a drug can act on. This is called biomarker testing. For some cancers, nearly everyone has the target, so testing may not be needed. Your care team explains what applies to you.
▸Can a drug be both immunotherapy and targeted therapy?
Sometimes. Monoclonal antibodies are lab-made proteins that attach to specific targets on cancer cells. Some are described as immunotherapy because they help the immune system see the cancer, and some are described as targeted therapy. The categories can overlap.
▸Are the side effects the same?
No, they differ. Immunotherapy side effects often happen when the revved-up immune system also acts against healthy cells. Targeted therapy side effects commonly include diarrhea and liver problems, among others. Your care team reviews what is most likely for your treatment.
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