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.

Recent studies have shown that for some men with early prostate cancer, a short course of hormonal therapy (2-6 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.

Hormonal therapy is also sometimes given before prostatectomy to shrink the cancer, although this can make the surgery more difficult and harder to stage the cancer.

In cancers which have broken through the capsule of the prostate gland a three year course of treatment with hormonal therapy may be advised to reduce the risk of the cancer spreading. This treatment may also be continued indefinitely.

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 or tiredness. The length of time for which hormone treatment works is variable but can be for many years. Your doctor will monitor your response to treatment by assessing any symptoms and examining you. They will also measure your PSA level - this is usually a very good guide to the effectiveness of the treatment.

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).

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.

Side effects
Unfortunately most hormonal therapies usually cause the inability to have an erection (sexual impotence) and loss of sexual desire. With orchidectomy this is permanent and with drugs or tablets it normally continues for as long as the treatment is given. If the treatment is stopped the problem may disappear. Some types of anti-androgens are less likely to cause impotence than others.

In about half the men who have drug hormonal therapies the side-effect which causes the most problem is hot flushes and sweating. Flushes do stop if the treatment is stopped, and in the meantime there are some medications that can help.

Hormonal treatment can also cause you to put on weight, and to feel constantly tired, both physically and mentally. The tiredness gets better if the drug treatment is stopped.

Some drugs (most commonly flutamide and bicalutamide) may also cause breast swelling and tenderness. This can often be avoided by giving a low dose of radiation to the breast tissue before starting treatment.

Different drugs have different side effects, so it is important to discuss the possible effects with your doctor before you start treatment. Being warned about possible side effects can make them easier to cope with at the time.

To reduce the risk of side effects, it may be possible to give the hormonal therapy for a few months and then stop for a time, before restarting it sometime later. This is known as intermittent therapy. At present it is not known whether this is as effective as continuous treatment, and it is only being given as part of research studies.

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.

Hormonal therapy
Treatment	Benefits	Unwanted effects
Subcapsular orchidectomy (removal of testicles which produces testosterone)	- Fairly simple operation - Helps up to 80% of men who have it - No tablets or injections needed	- Change in body image - May also need drug therapy at a later date - Side effects include hot flushes, loss of ability to get or maintain an erection, and loss of sex drive - these effects are not reversible
Injections	- No operation involved - Simple injection every 4 weeks or 3 months - Drugs can be stopped or changed if side effects are too great - Side effects may be temporary	- The side effects are the same as for orchidectomy, but the side effects can be reversible. (CancerBACUP has factsheets on individual drugs which give further details)
Tablets	- No operation involved - Drugs can be stopped or changed if side effects are too great - Side effects may be temporary	- Need to remember to take tablets - May cause a range of side effects these can include breast swelling and tenderness, hot flushes, inability to have erections and loss of sex drive. Side effects vary for each hormone drug. (CancerBACUP has factsheets on individual drugs which give details of their particular side effects)

More information on the prostate can be obtained from The Prostate Cancer Charity www.prostate-cancer.org.uk