What is targeted therapy?

Targeted therapy is a drug treatment that targets specific features of cancer cells to stop the cancer growing and spreading. The drugs circulate through the body, but work in a more focused way than chemotherapy and often have fewer side effects. However, targeted therapy does not work for everyone affected by cancer.

How targeted therapy works

The body constantly makes new cells to help us grow, replace worn-out tissue and heal injuries. Healthy cells multiply and die in an orderly way. Cancer cells are different – they multiply faster and keep growing when they aren’t supposed to. This happens because of changes in the genes of the cancer cells.

These gene changes help the cancer cells grow and survive, but they also create features within or on the surface of the cancer cells that can be targeted. Each targeted therapy drug acts on a particular feature, which is known as the molecular target or, simply, the target. The drug will only be given if the cancer cells have the target.

Targeted therapy may kill the cancer cells or slow their growth, causing the signs and symptoms of cancer to reduce or disappear. The drugs often have to be taken long term, but many people continue their usual activities and enjoy a good quality of life.

Who can have targeted therapy?

For some types of cancer, your doctor will test a sample to see if the cells contain a particular target that is helping the cancer grow. People with the same cancer type may be offered different treatments based on their test results.

How cancer is treated

Because each cancer is unique, people may have different treatment plans, even if their cancer type is the same. The three main cancer treatments are:

• surgery
• chemotherapy
• radiation therapy (also called radiotherapy).

Other treatments used for some types of cancer in some people include:

• targeted therapy
• immunotherapy
• hormone therapy.

Chemotherapy, targeted therapy, immunotherapy and hormone therapy are all drug therapies. They are known as systemic treatment because the drugs circulate throughout the body.

Cancer treatments may be used on their own or in combination. For example, you may have surgery to remove a tumour, followed by targeted therapy to stop the cancer returning. Sometimes targeted therapy is combined with chemotherapy.

Doctors will recommend the best treatment for you based on the type and stage of cancer, its genetic make-up, your age and your general health. 

How is targeted therapy different to chemotherapy?

Chemotherapy drugs affect all cells that multiply quickly. This means the drugs can kill cancer cells and also damage other cells that multiply quickly, such as healthy cells in the mouth, stomach, bone marrow or hair. This is why chemotherapy side effects often include mouth ulcers, nausea, low numbers of blood cells (leading to infections or anaemia) and hair loss.

Targeted therapy drugs work in a different way. They focus on the cancer cells, while limiting damage to healthy cells. Many people experience fewer side effects with targeted therapy, but it can still cause various side effects. Sometimes these can be serious.

When is targeted therapy used?

Using targeted therapy to treat cancer has improved survival rates for several types of cancer, and many people respond well. However, targeted therapy is not an option for everyone with cancer.

In Australia, targeted therapy drugs are now available for a range of cancers, including blood cancers such as leukaemia and lymphoma; common cancers such as bowel, breast, lung and melanoma; and other cancers such as cervical, head and neck, kidney, liver, ovarian, pancreatic, sarcoma, stomach and thyroid. For most of these cancers, targeted therapy is available only when the cancer is advanced. For some types, it is also available for early-stage cancer.

New drugs are becoming available every year, so talk to your doctor about the latest options.

Targeted therapy may be used:

• before surgery to reduce the size of a cancer (neoadjuvant therapy)
• after surgery to destroy any remaining cancer cells (adjuvant therapy)
• to treat cancer after initial treatments if the cancer has come back or hasn’t responded to other treatments (second-line therapy or palliative treatment)
• as long-term treatment to try to prevent the cancer coming back or control its growth (maintenance treatment).

Many targeted therapy drugs are not safe to use during pregnancy or while breastfeeding. Ask your doctor for advice about contraception. If you become pregnant, let your medical team know immediately.