Home  Prostate cancer Treatment Hormonal therapy
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Hormonal therapy treats prostate cancer by decreasing the supply or blocking the action of male hormones (androgens) such as testosterone that encourage prostate cancer growth. Hormonal therapy can slow the growth of the cancer and reduce the size of the tumour(s).
The following are the main types of hormonal therapy which may be used in prostate cancer:
Orchidectomy or surgical castration, is the surgical removal of the testes, which are the organs that produce 95% of the body’s testosterone. Since the testes are the major source of testosterone in the body, this procedure is classified as hormonal therapy rather than surgical treatment. The aim is to deprive the prostate cancer cells of testosterone, thereby causing the cancer to shrink and/or to prevent further growth of the tumour. The testicles are removed through a small incision in the scrotum.
Figure 1: Orchidectomy
Most men who undergo surgical castration will experience a loss of sexual desire and impotence. In addition, hot flushes frequently occur. Surgery is permanent and the effects cannot be reversed.
Medical castration, is achieved by using luteinizing hormone-releasing hormone agonists (LHRHa’s) (e.g. goserelin - ‘Zoladex’, leuprolide). They work by ‘switching off’ the production of male hormones from the testicles by reducing the levels of a hormone called luteinizing hormone. This hormone, is produced by the pituitary gland (a pea-sized gland located at the base of the brain which regulates and controls the release of hormones which directly or indirectly affect most basic bodily functions).
Figure 2: Medical-castration
LHRHa’s work just as well as orchidectomy in advanced disease
but do not involve surgery. They are also used in combination with
radiotherapy as adjuvant therapy for earlier disease.
They are given by injection either under the skin (subcutaneous) or into the muscle (intra-muscular). The injections are generally given every month or every 3 months.
Most men who undergo medical castration will experience a loss of sexual desire and impotence. In addition, hot flushes frequently occur. However, medical castration is potentially reversible. If treatment is stopped, testosterone is produced once again.
Non-steroidal anti-androgens (e.g. bicalutamide – ‘Casodex’, flutamide), which block the action and therefore prevent testosterone from working. They do this by attaching themselves to proteins (receptors) in the cancer cells. They are taken orally, as tablets.
They are used in combination therapy (with an LHRHa) in advanced
disease. Such therapy is known as Complete Androgen Blockade
(CAB),Total Androgen Blockade (TAB), or Maximal Androgen Blockade (MAB).
Bicalutamide is also used as monotherapy in locally advanced
disease where it has been shown to be as effective as medical or
surgical castration. It is also used in combination with prostatectomy or radiotherapy as adjuvant therapy for locally advanced disease.
Compared to castration, non-steroidal anti-androgens are less likely to reduce sexual desire or to cause impotence and hot flushes. However, some men will notice tenderness and/or enlargement of their breasts.Treatment is usually reversible and the effect of testosterone returns when treatment is stopped
Other hormonal agents which may be used to treat prostate cancer include female sex hormones (oestrogens) e.g. stilboestrol and steroidal anti-androgens e.g. cyproterone acetate.
Monotherapy – only one hormonal agent is given e.g. monotherapy with an LHRHa or anti-androgen.
In advanced disease, where the cancer has spread outside the
prostate and the pelvic area and therefore affects the bones,
monotherapy with an LHRHa e.g. goserelin is commonly used.
Although it will not cure advanced disease it will usually shrink the
tumour and slow it’s progress. Such treatment is useful in relieving the pain and other symptoms associated with advanced disease.
In locally advanced disease where the cancer has spread outside the
prostate but is still contained within the pelvic area (it has not spread to the bones), either monotherapy with an LHRHa or a non-steroidal
anti-androgen i.e. bicalutamide may be used.
Monotherapy may also be considered for patients with earlier stage
disease when the patient is unsuitable for, or unwilling to undergo,
radiotherapy or surgery.
Monotherapy with an LHRHa or a non-steroidal anti-androgen may
also be used in addition to surgery (radical prostatectomy) or
radiotherapy as:
Neoadjuvant Therapy – given before surgery or radiotherapy to
reduce the size of the tumour prior to these procedures.
Adjuvant Therapy – given after surgery or radiotherapy to kill any tumour cells, which may remain after these procedures. Goserelin has been shown to be very effective in this situation
Combination therapy – Two different types of hormonal agents e.g. an LHRHa plus a non-steroidal anti-androgen, are used together to increase the effect on the tumour.
Combination therapy not only prevents the action of testosterone
produced by the testes but also the small, but important amount which is produced by other glands i.e. the adrenal glands. Such therapy is sometimes called Complete or Maximal Androgen Blockade (CAB or MAB).
In advanced disease a combination of an LHRHa (e.g. goserelin) plus and non-steroidal anti-androgen (e.g. bicalutamide) can be used.
Clinical trials identify that men treated with such combination therapy may live longer than those treated with an LHRHa alone.
Combination therapy may sometimes be used prior to surgery or
radiotherapy (neoadjuvant) to reduce the size of the tumour.
Combination therapy may also be used for a short time (7-10 days) to minimise the effects of tumour flare. This can occur in a small
number of patients with advanced disease, when an LHRHa is given.
Tumour flare is a brief worsening of symptoms such as pain caused by a temporary increase in testosterone levels when an LHRHa is first started.
If you require hormonal treatment, your doctor will discuss the various treatment options with you. |
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