Targeted therapy goes after specific proteins or pathways that cancer cells need to grow and multiply. It is usually chosen based on tests of a tumor sample.

What is targeted therapy?

Cancer cells need certain proteins and pathways to grow and divide. Targeted therapy uses medicines that go after these proteins and stop the cancer from growing and spreading.

There are two main groups of medicine:

Small molecules: usually taken as pills or capsules. They get inside the cell.
Lab-made antibodies: usually given through a vein. They attach to a target on the cancer cell.

This treatment is part of “precision medicine,” which means choosing treatment based on the biological features of each patient’s tumor. Targeted therapy should not be thought of as free of side effects; sometimes the side effects are serious.

Who is it for?

Targeted therapy is only for cancers that have a suitable target. Before suggesting it, your doctor usually does a biomarker test on a sample of the tumor. Sometimes you already have a tissue sample, and sometimes a new biopsy is needed. The risk of a biopsy depends on the location and size of the tumor, and your doctor will explain it.

If the test shows there is a suitable target, targeted therapy may be suggested. It is sometimes given alone and sometimes together with chemotherapy, radiation therapy, or immunotherapy.

Every patient’s treatment plan is different; ask your doctor about your own situation.

How is targeted therapy given?

Pills or capsules: usually at home, at the times and in the way your doctor sets.
IV infusion: at a doctor’s office, a clinic, or a hospital outpatient unit.

The schedule may be daily, weekly, or monthly, and some medicines are taken in cycles with a rest period. Take the medicine exactly as directed. Do not raise or lower the dose yourself. If you miss a dose, do not decide on your own what to do; ask your doctor or pharmacist. Write down your dose times on paper or on your phone so you do not forget.

Some medicines interact with food, other medicines, or herbal products. Tell your doctor and pharmacist about all the medicines, supplements, and herbs you take.

During treatment, your doctor will see you regularly and do blood tests and imaging. For example, some medicines need liver function checked with blood tests or blood pressure monitored. These follow-ups are part of treatment, and you should not skip them. Over time, cancer cells can become resistant. If this happens, your doctor will change the plan. For this reason, targeted therapy is sometimes combined with other medicines.

What is each session or visit like?

If your medicine is a pill, your visits are for checkups and tests. Write down a list of the times you take your medicine and your side effects, and bring it with you.

If your medicine is given by IV, a blood test is done first, and then a nurse gives the medicine through a vein. How long it takes depends on the medicine. If you have itching, chills, trouble breathing, or dizziness during the infusion, tell the nurse right away.

Common side effects and how to care for yourself

Side effects depend on the medicine. The most common are:

Diarrhea and liver problems (followed with blood tests)
Rash and dry skin. Keep your skin moisturized, protect it from the sun, and do not use any cream or medicine on your own.
High blood pressure. If needed, check your blood pressure at home and share the results with your doctor.
Mouth sores and changes to nails and hair.
Fatigue. Rest, and save important tasks for the hours when you have more energy.
Problems with blood clotting and wound healing.
In very rare cases, a hole in the wall of the digestive tract.

Before you start, ask your doctor which side effects are more likely with your medicine and which symptoms you should report. Many side effects can be managed with medicine or a change in the schedule, and most go away after treatment ends. If you have to stop the medicine because of a skin rash or any other side effect, make that decision together with your doctor.

When to call right away

Call your care team or go to the emergency room if you:

Have severe belly pain, black or bloody vomit, or black stool
Have severe or long-lasting diarrhea and cannot keep fluids down
Have a fever of 38 degrees Celsius (100.4 degrees Fahrenheit) or higher
Have unusual bleeding
Have trouble breathing, chest pain, or swelling in one leg
Have a severe rash, blisters, or sores
Have yellow eyes or skin
Have a severe headache with high blood pressure, or sudden weakness

If you have severe trouble breathing, signs of a stroke, or chest pain, call 115 (Iran’s emergency number).