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Targeted therapy

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Targeted therapy includes a range of treatments that target the genes, proteins or tissues that make cancer cells different from normal cells, or that contribute to cancer cell growth. This means that targeted therapies work differently from standard chemotherapy. They usually have fewer side effects, or the side effects are not as severe.

Targeted therapy can include treatments that switch off the genes that tell cancer cells to grow, or switch on the genes that tell cancer cells to die. Other types of targeted therapies can deliver toxic substances directly to the cancer cells to destroy them.

Targeted therapy is usually used in combination with other treatments, such as radiation therapy, chemotherapy or surgery.

Because targeted therapy only works on certain genes, proteins or processes, your child (and your child’s cancer) need to be matched to a targeted treatment. This requires genetic or molecular testing, which is usually done with a blood test or a biopsy.

Types of targeted therapy

There are two main types of targeted therapy – monoclonal antibodies (also called immunotherapy) and small molecule therapy.

Monoclonal antibodies attach to a specific target on the outside of the cancer cell or tissue around the cancer. Monoclonal antibodies are usually given intravenously. The therapy may serve different purposes:

  • Once the antibody attaches to a cancer cell, it may act as a ‘flag’ to your child’s own immune system to destroy that cell.
  • The antibody can block growth receptors on the surface of the cancer cell, so that substances that make the cancer cell divide cannot reach the cancer cell.
  • The antibody may have radiation therapy attached to it. This is called radioimmunotherapy, and it allows low doses of radiation to be delivered right to the cancer cell without affecting healthy cells.
  • The antibody may have chemotherapy attached to it. When the antibody attaches to the cancer cell, the chemotherapy is delivered to the cancer cells and not to healthy cells.

Small molecule therapies are often taken orally. They are specially designed medicines that block processes that make cancer cells grow, survive or spread to other parts of the body. Small molecule therapies can include targeting specific growth factors.

Targeted therapies are helping to provide new ways to treat cancer in addition to traditional treatment options such as chemotherapy. However, targeted therapies have some limitations:

  • If your child does not have the target gene or protein, the therapy will not work.
  • If your child does have the target gene or protein, it does not guarantee that the treatment will work.
  • The cancer may become resistant to the treatment, which means that targeted therapy may work at first but then stop working.

Side effects of targeted therapy

Although targeted therapy aims to specifically target cancer cells and not healthy cells, it can still have side effects. People receiving targeted therapy often develop skin, hair, nail or eye problems. They may also develop high blood pressure, and problems with bleeding, blood clotting or wound healing.

Targeted therapies affect each person differently – your child may experience none, some or many of these problems.

Medicines and other treatments are available to help deal with many of these side effects. Your child’s doctor will discuss these with you.

Some of these side effects seem quite severe, and can be very distressing for you and your child. However, the benefits of targeted therapy usually outweigh the risks. Your child’s doctor will discuss the risks and benefits with you.

published: Sunday, 23 August, 2015