Hormonal therapies (also called endocrine therapies) are drugs used to treat women with breast cancer who have hormone receptors on their breast cancer cells. Hormone receptors are proteins on the surface of a cell that allow the cell to bind to hormones. When breast cancer cells have hormone receptors on them, this means the growth of the cancer cells is affected by female hormones. Breast cancer cells that have hormone receptors on them are said to be ‘hormone receptor positive’. About two-thirds of women with breast cancer have hormone receptors on their breast cancer cells. Your pathology report shows whether your breast cancer cells are hormone receptor positive. You can ask your doctor for a copy of your pathology report. There are two types of hormone receptor – oestrogen receptors and progesterone receptors. Hormonal therapies may be suitable for women with either type of receptor on their breast cancer cells.
Hormonal therapies may be used in addition to surgery, radiotherapy and chemotherapy, or on their own.
Note: Hormonal therapies used to treat breast cancer are not the same as hormone replacement therapy used to manage symptoms of menopause.
Menopause and oestrogen production
All women produce the hormone oestrogen; however, it is produced differently before and after menopause.
- Before menopause (pre-menopause), the ovaries are the main source of oestrogen.
- Around the time of menopause (peri-menopause), the ovaries stop producing female hormones, including oestrogen. This typically happens when women are in their late forties and early fifties. Women may experience a number of physical symptoms during menopause, including menstrual irregularities, hot flushes and sleep disturbances.
- After menopause (post-menopause), monthly menstrual periods have stopped. The body still produces small amounts of oestrogen by converting hormones called androgens into oestrogen. Androgens are produced by the adrenal glands, which are above the kidneys. They are converted into oestrogen by a hormone called aromatase which is produced mainly by fatty tissue.
How do hormonal therapies work?
Hormonal therapies stop breast cancer cells with hormone receptors from growing by blocking either the production of female hormones or the ability of hormones to get into cancer cells.
Why take hormonal therapies?
Clinical trials have shown that hormonal therapies lower the risk of breast cancer coming back (in the breasts and in other parts of the body). The hormonal therapy tamoxifen and surgical removal of the ovaries have both been shown to lower the risk of dying from breast cancer. However, for newer drugs, such as the new (selective) aromatase inhibitors, there are not yet enough long-term results from clinical trials to measure the effect of treatment on the risk of dying.
When should I start taking hormonal therapies?
Hormonal therapies are usually taken once your other treatments for breast cancer, such as surgery, radiotherapy and chemotherapy, have finished.
Who should I talk to about hormonal therapies?
Your treating doctor or specialist will consider the most appropriate treatment options for you and will discuss whether hormonal therapies are recommended in your case. If you have any questions, you should refer these to your oncologist, breast care nurse or general practitioner.
It is important that you talk to your treating doctor or specialist about which hormonal therapies may be suitable for you, the possible side effects of treatment and ways of managing these side effects if they develop.
If you change general practitioners once you have started taking hormonal therapies, it is important to let him/her know what you are taking.
