Recent advances in the treatment of prostate cancer

The recent announcement by researchers at the Royal Marsden Hospital, London, that a new drug, abiraterone, has been developed, with potential benefit to patients suffering from advanced cancer of the prostate, was indeed welcome news particularly as the lead researcher, Dr Johann de Bono, is Maltese.

However certain aspects of this new development need clarification. As often happens when a new drug is announced in the media there is an immediate demand for it by patients who have a vested interest, particularly if suffering from cancer, and therefore there is a need to inform people about any innovative drug. This drug is not a chemotherapeutic agent in the sense that it does not act directly on the cancer cells of the prostate, but rather manipulates and blocks the hormones on which the cancer is dependent. In this respect it is not an innovative procedure as hormone manipulation has been available and successfully used for many years. However, it does have a distinctive mode of action.

It was in 1941 that Charles Huggins published a seminal paper in which he argued that cancer of the prostate, which kills thousands of men worldwide, was dependent for its growth and propagation on the male hormone testosterone, which is mainly produced in the male testicles (although some five per cent is formed in the adrenal glands found in both sexes). Dr Huggins argued that if this hormonal supply is cut off this may possibly stop the growth and progression of the tumour and perhaps even cause its shrinkage and regression. He was proved right and was honoured by the award of the Nobel Prize in Medicine (1966). The main problem with this intervention was that in order to block testosterone formation Dr Huggins advocated removal of the patient's testicles. This operation, known as orchidectomy, was, and still is, a successful procedure but for obvious reasons not popular with men.

A major breakthrough occurred in the mid-1980s when injectable and oral drugs were developed which either reduced the production of testosterone or blocked its action on the prostate gland thus obviating the need to remove the testicles. As happened recently with abiraterone, these drugs were then hailed as "miraculous" and indeed to a certain extent proved to be so as patients with painful cancer foci in their bones became pain free with an extended and much improved quality of life.

As a committed member of the European Organisation For Research and Treatment of Cancer (EORTC) the Department of Urology (with the collaboration of the Department of Oncology) at St Luke's Hospital took part in extensive research on these drugs which has resulted in greater understanding in their use and limitations and have benefited hundreds of Maltese patients. Many of these European clinical trials are still ongoing. It is therefore very satisfying that another Maltese is pursuing this type of research in London.

So what about this new drug abiraterone? The recent media hype was rather premature as Dr de Bono himself admitted in a BBC interview. While there is no doubt that this is a very promising development there are many questions which need to be answered. For example, is this drug better than the hormone manipulators already available? Will it significantly reduce the morbidity and mortality of cancer of the prostate? What are its short and long term side effects?

When will it become available for clinical use and at what cost? For these questions to be answered Phase 3 trials must be concluded on at least 1,200 patients over a period of five or more years. To date the drug has been tested for a few months on some 250 patients. Much more work is required before one can assess the full potential of this drug. It appears to be very promising particularly in advanced cases of prostate cancer which have become resistant to conventional hormone and chemotherapy and thus gives a new hope to prostate cancer sufferers. One awaits further reports from Dr de Bono's research team.

One welcome effect of the extensive media coverage of this drug is the fact that attention has been drawn yet again to cancer of the prostate in males which unfortunately still kills thousands world-wide. If diagnosed early it can be cured. Every man above the age of 50 should have at least a yearly check-up for this condition which can nowadays be diagnosed by clinical examination and a specific blood test. Even in this sphere of early diagnosis there is ongoing research to improve our diagnostic tools. Unfortunately, many men are still too complacent.

Prof. Cutajar is an honorary member of the European Organisation For Research and Treatment of Cancer (Genito-Urinary).