Hormone therapy for prostate cancer

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How hormones work These tumours are stimulated by the bodies own hormones (the male hormone testosterone). Stopping the bodies hormones reaching the tumour cause the cancer cells to stop growing and in some cases shrivel up and die (self destruct - apoptosis).  Hormone therapies work in three main ways. 

• The first way is to block the production of the bodies own hormones. One straightforward way of doing this is to surgically remove the testis (orchidectomy). Some drug therapies chemically do the same thing by blocking the signal from the brain to the  testis - these include goserelin (Zoladex), Leuproelin (Prostap) collectively called LHRH blockers. 
• The second way hormone therapies work is to fool the signal pathway between the brain (pituitary) and the testes by increasing the blood levels of another hormone produced in the body so in turn the brain thinks they are producing too many hormones including testosterone and as a consequence switches off the driving signal by itself - this results in reducing the blood level of testosterone. Drugs which act in this way include stilboestrol and cyproterone acetate.
• The third way to stop the bodies hormones stimulating cancer cells to grow is to block the cells ability to read the signal from the hormones in the blood stream. Cancer cells have receptors in the same way as a TV needs an aerial. If the aerial is damaged the TV can't show a clear picture. In the same way if the receptor on the cell is blocked is can't be influences by the bodies hormones, despite often normal levels in the blood stream.  In prostate cancer the receptors are called androgen receptors, Although they are not easy measured they can be blocked by casodex or flutamide.

How are hormones used Hormones are used in 4 settings; [1] Hormone cytoreduction, [2] Adjuvant after radiotherapy or surgery[3] Primary hormone therapy  [4] Hormone  therapy for metastatic disease. 

[1] Hormone cytoreduction Hormones are usually used for a period of 3-6 month pre-radiotherapy in this setting and ha three advantages:- 

• It reduces the volume of bulky prostate cancer and the radiation target volume by 50% and 40% respectively  thus allowing smaller radiotherapy field and less side effects. 

• Reducing the volume then allows dose escalation and higher likelihood of local control.

• Preparing the gland with hormones sensitizes the cells to radiotherapy increasing the likelihood or cure. 

[2] Adjuvant therapy For patient with disease which has a moderate or high risk of relapsing after primary treatments a number of studies have shown that between 1-3 years hormones my reduce this risk.  

[3] Primary hormone therapy. The average response duration from hormone therapy is 2 years. Extrapolating this into early prostate cancer means that the treatment decision can be delayed on average by 2 years with this treatment. If a man has a life expectancy less than this, hormone therapy alone may be appropriate. In the majority of men this option is not appropriate:-

[4] Hormone therapy for disease which has spread outside the gland (bones, lymph nodes etc). This is a palliative treatment option. 

What hormones are used:

[1] Orchidectomy (removing the hormone producing part of the testes)

[2] LHRH agonists eg. Zoladex

[3] Steroidal antiandrogens eg. cyperoterone acetate

[4] Non-Steroidal anti-androgens eg. casodex, Flutamide

[5] Oestrogens eg. stilboestrol

Further general information Your doctors and specialist nurses are in an ideal position to give you relevant information on your disease and treatment as they know your individual circumstances. Cancerbackup has a help line (0808 800 1234) and a prize winning video available in English, Italian, Urdu, Bengali, Gujarati & Hindi explaining Radiotherapy & Chemotherapy. Cancernet.co.uk has over 500 pages describing cancer, its management, practical tips and tool which patients, their carers and their doctors have found helpful during the cancer journey.