Prostate cancer is driven by hormones. So by reducing hormones, it is possible to slow the growth of the cancer. This is known as hormone therapy, also known as androgen deprivation therapy (ADT), and is the standard first treatment when prostate cancer has spread (metastatic prostate cancer).
Testosterone is a male sex hormone (or androgen), which is produced by the testicles. It is vital in reproductive and sexual function. Hormone therapy reduces testosterone levels, and can often keep the cancer under control for several years by shrinking it, delaying its growth and reducing symptoms. How well hormone therapy controls the cancer is different from one man to another. It depends on how aggressive the cancer is, and how far the cancer has spread when you start hormone therapy.
Your doctor will speak with you about the different types of hormone therapy available and what is best for you, depending on your specific needs and situation. There are three main types of hormone therapy for advanced prostate cancer.
Injections to stop the production of testosterone
Injections block the messages from the brain to make testosterone, or block its action in the tissues. The drug (luteinizing hormone releasing hormone (LHRH) agonist*) can be injected under the skin or into the muscle monthly or every 3, 4 or 6 months.
Tablets to block the effects of testosterone (anti-androgens)
Anti-androgen drugs stop testosterone from getting to the prostate cancer cells so they are not able to grow. They are taken as tablets and may be used in combination with injections (see above) or orchidectomy (see below) to completely stop the action of testosterone in the body because they are not as effective on their own.
This form of hormone therapy involves the surgical removal of the testicles. Even though it involves surgery, its main effect is as a form of hormone therapy. Unlike other types of hormone therapy, orchidectomy cannot be reversed. It is important for you to talk with members of your healthcare team to make sure this is the most appropriate option for you.
Listed below are some questions you may want to ask members of your healthcare team about the different types of hormone therapy:
- Why is this type of hormone therapy being recommended to me?
- Why are the other types not being recommended to me?
- What are the advantages and disadvantages of this type of hormone therapy over the other types?
Hormone therapy can cause side effects such as loss of libido, erectile difficulties, hot flushes, fatigue, weight gain, loss of muscle mass and strength, thinning of the bones, risk of heart disease, and increased risk of developing or exacerbating existing diabetes.
You can read more about side effects from hormone therapy in one of the booklets in this series: Side Effects.
In some situations, after you have been on hormone therapy for a while your doctor may suggest different ways of using hormone therapy such as intermittent androgen deprivation (sometimes called intermittent hormone therapy) and combined androgen blockade (sometimes called maximal androgen blockade).
Intermittent androgen deprivation – This involves stopping treatment when test results (e.g. PSA) show that you are responding well to the hormone therapy. Treatment starts again when it is needed. Only using the therapy when it is needed will reduce the impact of side effects on your quality of life. However, this approach may not be as effective compared to if hormone therapy had been administered continuously, or quite as good in terms of overall survival, however this depends on the individual.
Combined androgen blockade (CAB) – This is when different types of hormone therapy are used together. The most common way of giving CAB is usually an injection (LHRH agonist) and anti-androgen together. It is not commonly used as a first treatment for metastatic prostate cancer because it increases the risk of side effects.
*LHRH is produced in the brain to stimulate the pituitary to make luteinizing hormone (LH). This causes cells in the testicles to make testosterone, the male hormone. LHRH agonists are drugs that affect the production of LH.