Hormone therapy is a treatment that uses medicines to block or lower the amount of hormones in the body to slow down or stop the growth of cancer.
What hormones are
Hormones are natural substances made by glands in our bodies. They are carried around our body in our bloodstream and act as messengers between one part of our body and another.
Hormones are responsible for many functions in our body, including the growth and activity of certain cells and organs. The endocrine system is the network of glands that make hormones.
How hormone therapy works
Some cancers use hormones to grow or develop. This means the cancer is hormone sensitive or hormone dependent.
Hormone therapy for cancer uses medicines to block or lower the amount of hormones in the body to stop or slow down the growth of cancer.
Hormone therapy stops hormones being made or prevents hormones from making cancer cells grow and divide. It does not work for all cancers.
Cancers that can be hormone sensitive include:
- breast cancer
- prostate cancer
- ovarian cancer
- womb cancer (also called uterine or endometrial cancer)
Types of hormone therapy
The type of hormone therapy you have depends on a number of factors, including your type of cancer. Below is some information about different types of hormone therapy.
The female hormones oestrogen and progesterone affect some breast cancers. Doctors describe these cancers as oestrogen receptor positive (ER+) or progesterone receptor positive (PR+) or both. Hormone treatment for breast cancer works by stopping these hormones getting to the breast cancer cells.
You may have more than one type of hormone therapy to treat breast cancer. For early breast cancer, it aims to stop the cancer coming back.
Tamoxifen works by blocking the oestrogen receptors. It stops oestrogen from telling the cancer cells to grow.
Tamoxifen is one of most common hormone therapies for breast cancer. Women who are still having periods (are premenopausal) and women who have had their menopause (are postmenopausal) can take tamoxifen.
Hormone therapy (tamoxifen or raloxifene) might be offered to people at high risk of breast cancer. This is called chemoprevention. This is not suitable for everyone.
Speak to your doctor if you think you are at high risk of breast cancer.
You might have an aromatase inhibitor if you have been through the menopause.
After menopause, your ovaries stop producing oestrogen. But your body still makes a small amount by changing other hormones (called androgens) into oestrogen. Aromatase is the enzyme that makes this change happen. Aromatase inhibitors block aromatase so that it can’t change androgens into oestrogen.
Luteinising hormone (LH) blockers
A gland in the brain called the pituitary gland produces luteinising hormone (LH) which controls the amount of hormones made by the ovaries.
LH blockers are drugs that stop the production of luteinising hormone. They do this by blocking the signal from the pituitary gland to the ovaries. So the ovaries stop making oestrogen or progesterone.
You will only have this treatment if you haven’t had your menopause yet. After menopause, your ovaries don’t produce hormones, so this type of drug won’t help.
One LH blocker used for breast cancer is goserelin (Zoladex).
Prostate cancer depends on testosterone to grow. Hormone therapy blocks or lowers the amount of testosterone in the body.
This can lower the risk of an early prostate cancer coming back when you have it with other treatments. Or, it can shrink an advanced prostate cancer or slow its growth.
Luteinising hormone (LH) blockers
A gland in the brain called the pituitary gland produces luteinising hormone (LH). This controls the amount of testosterone made by the testicles.
LH blockers are drugs that stop the production of luteinising hormone. They do this by blocking the signal from the pituitary gland to the testicles. So the testicles stop making testosterone.
LH blockers for prostate cancer include goserelin (Zoladex), leuprorelin (Prostap) and triptorelin (Decapetyl).
Prostate cancer cells have areas called receptors. Testosterone attaches to these receptors and that can encourage the cells to divide so that the cancer grows.
Anti androgen drugs work by attaching themselves to these receptors. This stops testosterone from reaching the prostate cancer cells.
There are different types of anti androgens including bicalutamide (Casodex), cyproterone acetate (Cyprostat) and flutamide (Drogenil).
Gonadotrophin releasing hormone (GnRH) blocker
Gonadotrophin releasing hormone (GnRH) blockers stop messages from a part of the brain called the hypothalamus that tell the pituitary gland to produce luteinising hormone.
Luteinising hormone tells the testicles to produce testosterone. So blocking GnRH stops the testicles producing testosterone. The drug degarelix (Firmagon) is a GnRH blocker.
Other hormone therapies
There are other newer hormonal treatments for prostate cancer. These therapies include:
The female hormones oestrogen and progesterone affect the growth and activity of the cells that line the womb. Doctors use progesterone treatment to help shrink larger womb cancers or to treat womb cancers that have come back.
There are different types of progesterone that doctors can give including medroxyprogesterone acetate (Provera) and megestrol (Megace).