Targeted therapy for breast cancer
Targeted therapy uses drugs that work in a different way to chemotherapy drugs. While chemotherapy affects all rapidly dividing cells, targeted therapy attacks specific targets inside cancer cells.
The targeted therapy drugs that are currently available do not work for all types of breast cancer. They are useful only for breast cancers that are growing in response to the HER2 protein. These HER2 positive breast cancers make up about 15−20% of all breast cancers. For early or locally advanced breast cancer in both women and men, the main targeted therapy drug is trastuzumab (brand name Herceptin). Other drugs are available for advanced breast cancer.
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Trastuzumab is usually referred to by the brand name Herceptin. This targeted therapy works by attaching itself to HER2 positive breast cancer cells, destroying the cells or reducing their ability to divide and grow. Herceptin also encourages the body’s own immune cells to help destroy the cancer cells.
Herceptin is used together with chemotherapy. It has been shown to increase the effect of chemotherapy drugs on early breast cancer. Some people receive Herceptin as an injection, but others are given it via a drip into a vein (infusion). You will usually have a dose every three weeks, although some people may have weekly doses.
The first infusion will take up to 90 minutes. This is called the loading dose. The following infusions take 30–60 minutes each, and they will continue for up to 12 months. The first four doses are given while you are having chemotherapy treatment.
Your medical team will monitor you for side effects. Often these will be caused by the chemotherapy. This means that once chemotherapy finishes and you are continuing with Herceptin for another nine months, most side effects ease. For example, hair grows back, there is no nausea or vomiting, and you no longer need regular blood tests.
Although side effects from the Herceptin itself are uncommon, they can include fever, diarrhoea, headache and a rash. In some people, Herceptin can affect how the heart works, so you will have tests to check your heart function before and during treatment. Ask your doctor for more information about these tests.
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Prof Christobel Saunders, Professor of Surgical Oncology and Head, Division of Surgery, The University of Western Australia, and Consultant Surgeon, Royal Perth, Fiona Stanley and St John of God Subiaco Hospitals, WA; Dr Marie-Frances Burke, Radiation Oncologist, Medical Director, Genesis CancerCare Queensland, QLD; Kylie Campbell, Breast Care Nurse and Clinical Lead, Murraylands, McGrath Foundation, SA; Carmen Heathcote, 13 11 20 Consultant, Cancer Council Queensland, QLD; Annmaree Mitchell, Consumer; Sarah Pratt, Nurse Coordinator, Breast Service, Peter MacCallum Cancer Centre, VIC; Dr Wendy Vincent, Breast Physician, Chris O’Brien Lifehouse and Royal Hospital for Women, Randwick, NSW, and Clinical Director BreastScreen NSW, Royal Prince Alfred Hospital, NSW; A/Prof Nicholas Wilcken, Director of Medical Oncology, Westmead Hospital, and Co-ordinating Editor, Cochrane Breast Cancer Group, NSW. We also thank the health professionals, consumers and editorial teams who have worked on previous editions of this title. This booklet is funded through the generosity of the people of Australia.
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Targeted therapy is a type of drug treatment that attacks specific features of cancer cells, known as molecular targets, to stop the cancer growing and spreading. Other names for targeted therapy include biological therapies and molecular targeted therapy.