Prostate cancer and hormonal therapies

Prostate cancer is often treated with hormonal therapies. These may be given on their own or with radiotherapy.

Prostate cancer needs the male sex hormone, testosterone, to grow. Testosterone is produced by the testicles. Hormonal therapies for prostate cancer lower the level of testosterone in the body, or they prevent it from attaching to the cancer cells. This can help slow down or stop the growth of the prostate cancer cells.

Hormonal therapies include:

  • GnRH analogues – these drugs ‘switch off’ the production of testosterone.
  • GnRH blockers – these also stop the testicles from producing testosterone.
  • Anti-androgens – these drugs block the testosterone from getting to the prostate cancer cells.
  • Abiraterone acetate – this reduces the amount of testosterone being made.
  • Oestrogen treatment – this reduces testosterone levels.
  • Surgery – this removes the part of the testicles that produces testosterone.

These treatments can cause side effects including sexual effects, hot flushes, tiredness and mood changes. Your doctor will tell you more about what to expect and what can help manage them.

Prostate cancer and hormonal symptoms

Prostate cancer is often treated with hormonal therapies that may be used on their own or combined with radiotherapy. These treatments can cause side effects, which vary depending on the type of hormonal treatment you're having. The side effects can range from being mild to severe.


Testosterone is a male sex hormone. Hormones are substances that occur naturally in the body. They control the growth and activity of cells.

Testosterone plays an important role in:

  • sex drive (libido)
  • getting an erection
  • facial and body hair
  • muscle development.

Testosterone is mainly made by the testicles. The adrenal glands, which are on top of the kidneys, also make a small amount of testosterone. The pituitary gland in the brain controls the amount of testosterone the body makes. It does this by making luteinising hormone (LH), which stimulates the testicles to make testosterone.

Prostate cancer needs testosterone to grow. Hormonal therapies for prostate cancer work by lowering the level of testosterone in the body, or by stopping testosterone reaching the cancer cells. This can help slow down or stop the growth of the prostate cancer cells.

Hormonal therapy treatments

There are different types of hormonal therapy.

GnRH analogues 

GnRH (gonadotrophin-releasing hormone) analogues, or pituitary down-regulators, are drugs that reduce the levels of luteinising hormone made by the pituitary gland. This stops the testicles from making testosterone. 

These drugs are given as a pellet or liquid injected under the skin. The injections may be given monthly or every three months or six months. 

When GnRH analogues are first given, they can cause a temporary increase in testosterone before levels drop. This may cause a short-term increase in prostate cancer symptoms, such as difficulty peeing or bone pain. This is called tumour flare. Anti-androgens may be prescribed to reduce tumour flare. 

Commonly used GnRH analogues:

GnRH blockers

GnRH blockers or GnRH antagonists stop the pituitary gland from making luteinising hormone and other related hormones. This stops the testicles from making testosterone. The only GnRH blocker currently available is degarelix (Firmagon®). It is given as an injection under the skin once a month. GnRH blockers don’t cause the temporary increase in testosterone levels that GnRH analogues can.


These drugs work by stopping testosterone from reaching prostate cancer cells. They're usually given as tablets. Anti-androgens may be given at the beginning of treatment with GnRH analogue hormonal therapy to prevent symptoms of tumour flare.

Commonly used anti-androgens are:

Abiraterone acetate (Zytiga®)

This drug reduces the levels of testosterone in the body. It works by interfering with a protein the body needs to be able to make testosterone in the testicles and adrenal glands. Abiraterone is taken once a day as a tablet. It is usually used in combination with GnRH analogue treatment or with surgery to remove the testicles. 


Oestrogen is a female sex hormone. Both men and women make oestrogen but men make much smaller amounts of oestrogen than women. Treatment with oestrogen can reduce testosterone levels. It is sometimes used in men who have prostate cancer that is no longer responding to other hormonal therapy drugs. The oestrogen most commonly used to treat prostate cancer is a drug called diethylstilbestrol. It is taken as a tablet once a day. 

Surgery (orchidectomy)

An orchidectomy, also called an orchiectomy, is an operation to remove the testicles. Sometimes only the part of the testicles that produces testosterone is removed (subcapsular orchidectomy). It's a simple operation that can be done as a day patient. After the operation, levels of testosterone are permanently reduced. This causes many of the same side effects that treatment with GnRH analogues and GnRH blockers cause. 

Side effects of hormonal therapy

Reducing the level of testosterone can cause a number of side effects. Some are linked with taking hormonal therapy for longer periods of six months or more, and are very unlikely to affect men on hormonal therapy for a shorter time.

Possible side effects include:

  • sexual effects
  • hot flushes
  • difficulty sleeping (insomnia)
  • tiredness (fatigue)
  • mood changes
  • breast swelling or tenderness

Men treated with hormonal therapy for six months or more may also have:

  • weight gain and loss of muscle strength
  • bone thinning
  • risk of heart disease and diabetes

We have more information on all these symptoms.

Back to Managing hormonal symptoms