What hormone therapy is

Hormones are natural substances made by glands in our bodies. The network of glands that make hormones is called the endocrine system. Hormones are carried in our bloodstream and act as messengers between one part of our body and another. They have lots of effects and one of these is controlling the growth and activity of certain cells and organs.

Some cancers use these hormones to grow. Hormone therapy for cancer is the use of medicines to block the effects of hormones. Not all cancers respond to hormone therapy. Doctors use hormone therapy for people with cancers that are hormone sensitive or hormone dependent. Cancers that can be hormone sensitive include breast cancer, prostate cancer, ovarian cancer, womb cancer (also called uterine or endometrial cancer) and kidney cancer.

Cancers that are hormone sensitive or hormone dependent need hormones to grow or develop. Hormone therapies can slow down or stop the growth of cancer by either

• Stopping hormones being made or
• Preventing hormones from making cancer cells grow and divide

There are a number of different types of hormone therapy. Which one you have depends on a number of factors, including your type of cancer. There is information below about 

• Breast cancer hormone therapy
• Prostate cancer hormone therapy 
• Womb cancer hormone therapy
• Ovarian cancer hormone therapy
• Kidney cancer hormone therapy

The female hormones oestrogen and progesterone affect some breast cancers. Doctors describe these cancers as oestrogen receptor positive or progesterone receptor positive, or both. Hormone treatment for breast cancer works by stopping these hormones getting to the breast cancer cells. There are different types of hormone therapies that doctors use to treat breast cancer, such as

• Tamoxifen
• Aromatase inhibitors
• Luteinising hormone (LH) blockers

You may have more than one type of hormone therapy to treat breast cancer. For early breast cancer, to try to stop the cancer coming back, you may have tamoxifen for 2 or 3 years, then switch to an aromatase inhibitor, depending on whether you have been through the menopause.We know from research that sometimes this can work better than having tamoxifen alone. There is research being done to find out how long someone needs to take tamoxifen, to get the most benefit. There is more information about this in the section about hormone therapy for breast cancer.

Tamoxifen

Tamoxifen is one of the most common hormone therapies used for breast cancer. Both pre and postmenopausal women can take tamoxifen. It works by stopping the hormone oestrogen from reaching cancer cells. Some breast cancer cells have areas called receptors. When oestrogen locks onto the receptors, it can encourage the breast cancer cells to divide so that the cancer grows. Tamoxifen blocks these receptors.

Aromatase inhibitors

You may 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. We need an enzyme called aromatase to make this change happen. Aromatase inhibitors block this enzyme so it can’t change androgens into oestrogen.

There are a few different types of aromatase inhibitor. There is more information about aromatase inibitors, including anastrozole (Arimidex), exemestane (Aromasin) and letrozole (Femara), in our cancer drugs section.

Luteinising hormone (LH) blockers

A gland in the brain, called the pituitary gland, controls the amount of sex hormones made by the ovaries. In women LH blockers are drugs that stop the ovaries making oestrogen or progesterone. They do this by blocking the signal from the pituitary gland to the ovaries.

You will only have this treatment if you haven’t yet had your menopause. 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 the male hormone testosterone for its growth. Hormone therapy aims to reduce or stop the body making testosterone and slow down or stop the growth of the cancer. There are different types of hormone therapy, including luteinising hormone (LH) blockers, anti androgens and gonadotrophin releasing hormone (GnRH) blockers.

Luteinising hormone (LH) blockers

A gland in the brain called the pituitary gland produces luteinising hormone (LH) that controls the amount of testosterone made by the testicles. LH blockers are drugs that stop the production of luteinising hormone. So the testicles stop making testosterone. 

LH blockers for prostate cancer include goserelin (Zoladex), leuprorelin (Prostap) and triptorelin (Decapetyl).

Anti androgens

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 so that they stop testosterone reaching prostate cancer cells. There are a few different types including bicalutamide (Casodex), cyproterone acetate (Cyprostat) and flutamide (Drogenil). You can find out more about these drugs in our cancer drugs section.

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. There is currently only one GnRH blocker and it is called degarelix (Firmagon). It is not yet widely used in the UK. You can find detailed information about degarelix in the cancer drugs section.

The female hormones oestrogen and progesterone affect the growth and activity of the cells that line the womb. Doctors give the hormone progesterone to help shrink larger womb cancers. Or to treat womb cancers that have come back. There are different types of progesterone treatment, including medroxyprogesterone acetate (Provera) and megestrol (Megace).

Some ovarian cancers have oestrogen receptors and it is thought that tamoxifen might be useful for these cancers. But it is not yet known whether hormone therapy is suitable for ovarian cancer. Doctors are doing research with tamoxifen and letrozole. There is more information about ovarian cancer research in our ovarian cancer section.

Sometimes when kidney cancer comes back, hormone therapy tablets called medroxyprogesterone (Provera) can control it for a while. Medroxyprogesterone is a man made version of the hormone progesterone. It is not used very often now. It generally has less effect on kidney cancer than biological therapies.