Targeted therapy for breast cancer

The therapeutic drugs target specific processes and structures that some breast cancer cells need to survive and grow. Normally, only the cancer cells exhibit these characteristics. Healthy cells are therefore usually unaffected by the treatment.

There are several types of targeted therapy drugs. The drug you receive, its dose and schedule depend on the type and stage of your breast cancer.  

The main types are:  

• Anti-hormone therapy, which reduces or inhibits the activity of hormones that stimulate tumour growth in oestrogen receptor (ER) or progesterone receptor (PR) positive breast cancer.  
• Monoclonal antibodies that attach to receptors on cancer cells. This helps the immune system to recognise the cancer cells and attack them in a targeted manner.
• Kinase inhibitors , which block the signals that stimulate cancer cell growth, for example in HER2-positive breast cancer or hormone receptor-positive breast cancer.
• Angiogenesis inhibitors, which prevent the tumour from developing blood vessels. This deprives them of oxygen and nutrients, causing them to die.  

In cases of metastatic breast cancer, targeted therapies can be combined with anti-hormone treatment. For example, for the treatment of metastatic breast cancer that is hormone receptor-positive and Her2-positive.  

Other types of targeted therapies include mTOR inhibitors, PARP inhibitors and antibody-drug conjugates.  

Targeted therapy only works on cancer cells with specific characteristics, so it is not necessary in every case. Your doctor will test your cancer cells for specific receptors or genetic changes to find out whether targeted therapy is suitable for you.

It may be suitable for:

• ER-positive or PR-positive breast carcinoma
• HER2-positive breast cancer
• HER2-low expressing breast cancer
• Triple-negative breast cancer
• BRCA1 or BRCA2 mutations

It can be used to treat these types of breast cancer in order to reduce the risk of recurrence or slow the growth of metastatic or advanced breast cancer. It can be given alone or in combination with chemotherapy or hormone therapy.

Your treatment team will carefully tailor the way you receive targeted therapy to suit you and your cancer, e.g. its type and stage. Your doctor will explain your individual treatment plan in more detail and help you understand what to expect.  

How the treatment is administered

Targeted therapy may be administered as:  

• Oral tablets
• Infusion into a vein
• Injection under the skin  

You are usually given treatment in the clinic and can go home on the same day.  

Your first session may take several hours, as your oncology nurse will need to monitor you for up to an hour after treatment to make sure you tolerate it well. If there are no problems, your next sessions will be quicker.  

Duration of treatment

The length of treatment depends on your individual needs. In some cases, targeted therapy is administered every three weeks for a period of several months to a year. For others, treatment may be lifelong, e.g. in the case of palliative care.  

The length of your treatment depends on the type of medicine you are taking, how well the cancer responds to it, and your overall health.  

Your doctor will regularly monitor your condition and discuss the treatment plan with you.  

Effects of treatment

Every person reacts differently to targeted therapy. Side effects vary depending on the type of medication and whether you are receiving other treatments. Your doctor will help you understand what to expect from your treatment plan and how to manage any side effects.

Common side effects include:  

• Flu-like symptoms, e.g. chills, fever, headaches
• Skin reactions, e.g. dry, itchy skin and rashes
• Feeling unwell and nauseous
• Diarrhoea  

Sometimes monoclonal antibodies can affect the heart. This may occur during or, less commonly, after treatment has been completed. Your doctor will check the health of your heart before and during treatment to keep an eye on it.  

If you notice any changes in your heart or your general health, please inform your oncology nurse so that we can help you.