Some breast cancers are stimulated by the hormone oestrogen. This means that oestrogen in the body ‘helps’ the cancer to grow. This type of breast cancer is called oestrogen receptor positive (ER+). Tests may also be done for progesterone (another hormone) receptors. The benefits of hormone therapy are less clear for people whose breast cancer is only progesterone receptor positive (PR+ and ER-). Very few breast cancers fall into this category. However, if this is the case for you your specialist will discuss whether hormone therapy is appropriate.
Hormone therapy, also called endocrine therapy, is a treatment that blocks the effect of oestrogen on breast cancer cells. It may be offered:
- to reduce the risk of breast cancer coming back after surgery
- to reduce the size of your cancer before surgery to remove it
- to treat breast cancer that has already come back or spread
Hormone therapy is usually started after surgery (known as adjuvant treatment), to reduce the risk of the breast cancer coming back. It may also reduce the risk of a cancer developing. If you’re having radiotherapy after surgery but not chemotherapy, hormone therapy may be started during or after the radiotherapy. If you’re having chemotherapy after surgery, hormone therapy will usually start after chemotherapy has finished. If your tumour is HER-2 receptor positive and you are then having trastuzumab (Herceptin), hormone therapy may be given at the same time. Your surgeon/oncologist will discuss which of the following endocrine treatment you are going to receive. They may change it in the future if they give you side effects.
The most commonly used hormone therapy drugs used to treat breast cancer are:
- aromatase inhibitors (anastrozole, exemestane and letrozole)
- goserelin (Zoladex)
- fulvestrant (Faslodex)
Hormone treatments are prescribed for 5-10 years depending on your individual circumstances. If you are having problems tolerating the side effects please contact us as there may be an alternative.