How Hormones Affect Prostate Cancer
Hormones are substances that occur naturally in the body. They control the growth and activity of normal cells.
Cancer of the prostate is dependent on the male hormone, testosterone, for its growth. Testosterone is produced by the testicles. By reducing the amount of testosterone in the body it is possible to slow down or stop the growth of the cancer cells. It can shrink down the tumour and symptoms will
often disappear completely.
The levels of testosterone in the body can be lowered by removing the part of the testicles that produce testosterone (subcapsular orchidectomy) or by using drugs. The drugs can be given as tablets or injections, or a combination of both.
Treatment of Early Prostate Cancer
Studies have shown that for some men with early prostate cancer, a short course of hormonal therapy (4-7 months) before and during radiotherapy improves the results of the radiotherapy treatment.
The drugs may be continued for 2-3 years after radiotherapy if cancer is advanced and there is a high risk that it has spread to other parts of the body – this is known as adjuvant therapy.
In cancers which have broken through the capsule of the prostate gland a treatment with hormonal therapy may be advised to reduce the risk of the cancer spreading. This treatment may also be continued indefinitely.
Treatment of Metastatic Prostate Cancer
Hormonal therapy is the standard treatment for prostate cancer which has spread or developed secondaries or metastases. Often there is very good shrinkage of the cancer and the disappearance of symptoms such as:
- Poor urinary flow
- Bone pain
- Tiredness
The duration of effectiveness varies but can last many years. Your doctor will monitor treatment response by:
- Assessing your symptoms
- Performing physical examinations
- Measuring your PSA (Prostate-Specific Antigen) level – this is usually a reliable indicator of treatment success.
Other Hormonal Treatments
Oestrogen treatment may be used to control the growth of the cancer for some men. The main drug used is a man-made oestrogen called diethylstilboestrol (DES). It can cause swelling of the breasts, and can increase the risk of developing blood clots. Steroids may also sometimes be used.
Injections
Some drugs `switch off’ the production of male hormones from the testicles by reducing the levels of a hormone (luteinising hormone) produced by the pituitary gland. They are called pituitary down-regulators or gonadotrophin hormone releasing hormone analogues (GHRH analogues), and are given by injection under the skin. The injections are given either monthly or every three months.
Commonly used GHRH analogues are goserilin (Zoladex), leuprorelin (Prostap), triptorelin (decapeptyl).
There is a newer class of injections, GHRH antagonists. An example being degarelix. These also reduce testosterone levels, but without the initial “flare” caused by the GHRH analogues. They work more quickly and do not require the concomitant taking of an anti-androgen. As they are relatively new, they are more expensive.
Tablets
Other hormonal therapy drugs work by attaching themselves to proteins (receptors) on the surface of the cancer cells. This blocks the testosterone from entering the cancer cells. They are called anti-androgens and are often given as tablets.
Commonly used anti-androgens are flutamide (Drogenil), cyproterone acetate (Cyprostat) and bicalutamide (Casodex).
Anti-androgens are also given with the first injection of pituitary down-regulator. This prevents `tumour flare’ which is an increase in symptoms connected with the first dose of treatment.
Subcapsular Orchidectomy (Removal of Testicles)
Subcapsular orchidectomy is a simple operation. A small cut is made in the scrotum (the sac which holds the testicles), and the testicles (which produce testosterone) are removed. The scrotum will be smaller than before. The operation can be done as a day patient under local anaesthetic.
If a general anaesthetic is used you may need to stay in hospital for two to three days. Sometimes both testicles are completely removed.
Many men find the idea of this operation very distressing and feel that it makes them less of a man. However some men do not find this a problem. Orchidectomy can be effective in controlling the cancer and reducing symptoms in up to 80% of men who have it.
After the immediate effects (some pain, and often swelling and bruising of the scrotum) the side effects of hot flushes and sexual impotence are similar to those of drug treatment. Subcapsular orchidectomy avoids the use of drugs and possible side effects such as breast enlargement and tenderness. It is often the option chosen by elderly men with no desire to have an active sex life.
If your doctor feels that hormonal therapy is an option for you they will discuss the benefits and unwanted effects of both drug treatment and surgery. These are outlined in the table below.
| Treatment | Benefits | Unwanted effects |
|---|---|---|
|
Subcapsular orchidectomy (removal of |
- Fairly simple operation |
- Change in body image |
| Injections |
- No operation involved |
- The side effects are the same as for orchidectomy, but the side effects can be reversible. |
| Tablets |
- No operation involved |
- Need to remember to take tablets |
More Information
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