Targeted therapy medicines work in a few different ways. They may:

• Turn off the process in cancer cells that causes them to grow and spread
• Trigger cancer cells to die on their own
• Kill cancer cells directly

People with the same type of cancer may have different targets in their cancer cells. So, if your cancer does not have a specific target, the medicine will not work to stop it. Not all therapies work for all people with cancer. At the same time, different cancers may have the same target.

To see if a targeted therapy might work for you, your health care provider may:

• Take a tiny sample of your cancer
• Test the sample for the specific targets (molecules)
• If the right target is present in your cancer, then you may receive the treatment

Some targeted therapies are given as pills. Others are injected into a vein (intravenous, or IV).

Targeted therapies can treat most types of cancers.

Your health care provider will decide whether targeted therapies may be an option for your type of cancer. You may receive targeted therapy along with surgery, chemotherapy, hormonal therapy, or radiation therapy. You may receive these medicines as part of your regular treatment, or as part of a clinical trial.

Providers thought that targeted therapies might have fewer side effects than other cancer treatments. But that turned out to be untrue. Possible side effects from targeted therapies include:

• Diarrhea
• Liver problems
• Skin problems such as rash, dry skin, and nail changes
• Problems with blood clotting and wound healing
• High blood pressure

As with any treatment, you may or may not have side effects. They may be mild or severe. Fortunately, they usually go away after treatment ends. It is a good idea to talk with your provider about what to expect. Your provider may be able to help prevent or lessen some side effects.

Targeted therapies are promising new treatments, but they have limitations.

• Cancer cells can become resistant to these medicines.
• The target sometimes changes, so the treatment no longer works.
• The cancer may find a different way to grow and survive that does not depend on the target.
• Medicines can be difficult to develop for some targets.
• Targeted therapies are newer and cost more to make. So, they are more expensive than other cancer treatments.
• The side effects may not be tolerated by some people.

Molecularly targeted anticancer agents; MTAs; Chemotherapy-targeted; Vascular endothelial growth factor-targeted; VEGF-targeted; VEGFR-targeted; Tyrosine kinase inhibitor-targeted; TKI-targeted; Personalized medicine - cancer

Do KT, Kummar S. Therapeutic targeting of cancer cells: era of molecularly targeted agents. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 26.

National Cancer Institute website. Targeted cancer therapies. www.cancer.gov/about-cancer/treatment/types/targeted-therapies/targeted-therapies-fact-sheet. Updated May 31, 2022. Accessed March 19, 2024.

Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.