Common questions about hormone therapy

What are hormones?

Hormones are substances that are produced naturally in the body and affect how the body works. They act as messengers carrying information and instructions from one group of cells to another. Hormones control many of the body’s functions, including how people grow, develop and reproduce.

Examples include: 

• the sex hormones oestrogen and progesterone, which control ovulation and menstruation; they are mainly produced in the ovaries but small amounts are made in body fat and the adrenal glands 
• the sex hormone testosterone, which causes the development of the male reproductive organs and other sexual characteristics, such as a deep voice and facial hair; testosterone is mainly produced in the testicles 
• hormones made by the thyroid, including thyroxine, which control the body’s metabolism. 

When is hormone therapy given?

Hormone therapy is used only for hormone-dependent cancers, such as some types of breast, uterine and prostate cancers.

Hormone therapy is often used with other cancer treatments: 

• before surgery or radiation therapy to shrink a tumour 
• after treatment to reduce the risk of the cancer returning 
• to slow the growth of cancer that has spread throughout the body and help manage symptoms. 

How do you have hormone therapy?

Hormone therapy may be given as tablets you swallow, injections or through a device placed in the uterus. For some cancers, you may have surgery to remove a part of the body to stop the production of hormones, e.g. your ovaries may be removed to stop the production of oestrogen (oophorectomy). 

How long do you have hormone therapy?

Hormone therapy can be used for a short time or long term. How long you have hormone therapy depends on the aim of the treatment, how the cancer responds and any side effects you have. In many cases, hormone therapy tablets or injections need to be taken daily or monthly for many years. Your treatment team can give you more details. 

Can I have hormone therapy if I take other hormones?

Menopause hormone therapy

Hormone therapy may interact with hormones used to treat the symptoms of menopause. If you were diagnosed with a hormone-dependent cancer, you will usually be advised not to take menopause hormone therapy (MHT, previously called hormone replacement therapy or HRT). If you were already on MHT when the cancer was diagnosed, you may need to stop using it because oestrogen may cause the cancer to grow.  

LGBTQI+ people

Hormone therapy for cancer can interact with hormones used by some trans and non-binary people as part of gender affirmation. It may also interact with hormones prescribed for people with an intersex variation. You may not be able to continue with these hormones during your cancer treatment. This can affect how you feel about your body and sense of self. Talk to your doctor about the options and what they mean for you. For more on this, see our general information for LGBTQIA+ people and cancer.