What is targeted therapy?
Targeted therapy is a form of cancer treatment that precisely targets cancer cells, destroying them or preventing them from growing and dividing. Targeted therapies can identify and attack abnormal cells based on proteins or DNA changes specific to the cancer cells while minimizing the impact on your healthy cells.
Targeted therapy for cancer is considered precision medicine or precision oncology, as it is a personalized approach tailored to findings in your cancer. It differs from traditional or standard chemotherapy, which kills both healthy cells and cancer cells. However, it is often combined with other treatments, including conventional chemotherapy, radiation therapy and surgery.
Types of targeted therapy
Many targeted therapies exist, and they can treat many kinds of cancer. However, targeted therapies often fall into two main categories: small-molecule drugs, which are tiny enough to enter a cancer cell, and large-molecule drugs, which work by attacking the proteins or enzymes on the cell’s surface.
Your doctor will determine which targeted therapy may be best for you after ordering lab tests and, possibly, a biopsy, which involves taking a sample of your tumor so it can be tested. The results of these tests help your team learn about your cancer and determine a personalized treatment plan for you.
What kinds of cancer does targeted therapy treat?
The Food and Drug Administration has approved targeted drug therapies to treat more than 30 different forms of cancer. Some drugs have been approved to treat more than one kind of cancer. Since targeted therapy is an individualized approach, your doctor will tailor your treatment to your specific type of cancer.
Common cancers treated with targeted therapy include:
How does targeted therapy work?
Targeted therapies can distinguish cancer cells from normal cells by detecting specific proteins, too much of a particular protein or changes in a cell’s DNA. The drugs then stop the cancer cells from functioning normally in various ways.
These include blocking the chemical signals that cause them to grow, changing their proteins, carrying toxins to make them die, or stopping them from making blood vessels or responding to hormones that cause them to grow. Targeted therapies can also trigger your immune system to attack the cancer cells.
When is targeted therapy used?
Your doctor may recommend targeted therapy based on the results of biomarker testing.
Each person’s cancer has unique biomarkers, which are genes, proteins or other substances that provide information about the cancer. Your cancer’s biomarkers can affect how you respond to treatment and whether targeted therapies are appropriate. Biomarker testing can help your doctor determine if your cancer has targets that can be effectively treated with a drug.
Cancer cells can become resistant to targeted therapy and find new ways to grow. Often, doctors combine targeted therapies with other treatments, such as radiation therapy, but some cancers can be treated using only targeted therapy.
What to expect
If you and your care team decide to move forward with targeted therapy, they will explain what to expect when it comes to treatment results, benefits and risks, and possible side effects.
How often you receive treatment will depend on your cancer type, the targeted therapy you receive and how your body responds to treatment. Targeted therapies are typically given in cycles—you might get treatment daily, weekly or monthly, with rest periods in between to allow your body to recover.
Since targeted therapies are relatively new, your team may recommend safety precautions to protect themselves, your family and your friends from exposure. Your care team will probably wear protective clothing during treatment. You can ask a friend or relative to accompany you to your appointment, but they might be asked to remain in a waiting room.
Possible side effects of targeted therapy
Like other types of cancer treatment, targeted therapies can cause side effects. These often depend on the type of drug used. They can also vary from one person to another. Some people have severe side effects, while others have mild or even no side effects.
Most side effects will go away soon after treatment ends. They could include:
- Allergic reactions (when receiving IV medications)
- Chronic or nonhealing wounds
- Coughing
- Diarrhea or constipation
- Fatigue
- Hair or skin color changes
- Heart damage
- High blood pressure
- Liver problems
- Mouth sores
- Nail changes
- Nausea or vomiting
- Numbness or tingling in hands and feet
- Problems with blood clotting
- Shortness of breath or difficulty breathing
- Skin problems, such as dry skin, rashes or sensitivity to light
- Swelling in your face, hands, feet or legs
Some drugs have also been linked to damage to organs, such as the thyroid gland or kidneys, and increased risk of other infections or a second cancer.
Most symptoms will improve as your healthy cells recover. However, targeted therapies are relatively new, so more research is needed into long-term side effects.