Genes show way to better prostate treatment
By Henry Llewen


Research has revealed how small variations in two genes largely determine how likely men are to develop prostate cancer, how rapidly the cancer will develop if it occurs and how likely those affected are to suffer a relapse after treatment.

These discoveries will save many lives and much suffering by enabling treatments and preventive measures to be better tailored to the individual's needs.

The discoveries have been made by scientists at Europe's first Male Cancer Research Centre, art of the United Kingdom's Institute to Cancer Research [ICRI in Surrey, southern England, and which is closely linked to the worldfamous Royal Marsden Hospital in London. The ICR was officially opened in November 2000.

Prostate cancer is expected to overtake both breast and lung cancer to become the most commonly diagnosed cancer in the UK by 20l8. The numbers of cases of testicular cancer diagnosed there have risen by 70 percent in the last 20 years, for reasons that are still unknown. Similar patterns of increase in cancers that affect only men can be seen in other countries.

If caught early the cure rate for testicular cancer is 96 per cent. But men tend to be more reluctant than women to discuss health problems, especially those which cause embarrassment such as problems affecting the prostate or testicles.

As well as the need for more research there is a need to change men's attitudes to such health problems so that they will seek medical advice about their symptoms earlier.

One of the genes which has been investigated at the ICR determines the structure of the receptor for a, male sex hormone, an androgen. This hormone stimulates the growth of prostate cancers, blocking the supply of androgen to the tumour is one highly effective way of treating prostate cancer.

Variations in the gene for this androgen receptor - which is known as the HAR gene - in turn cause small variation known polymorphisms in the structure of the receptor. These variations can greatly speed or slow the rate at which prostate cancer develops.

This is because a hormone can only stimulate cells normal or malignant, through receptors on the cell surfaces into which the molecules of hormones fit like keys into locks. If the lock is not quite the right Shape, then the key will not fit and the Stimulus to growth provided by the hormone will consequently be less effective.

This is why different variations in the HAR gene, causing differences in the structure of the androgen receptor, help to determine how fast prostate cancer will develop. They also help to determine how likely a patient is to suffer a relapse after treatment.

Another gene which research at the ICR has shown to affect prostate cancer is the gene for an enzyme which helps to defend the human body against damage by carcinogens - cancer-causing chemicals.

This gene is known as GST. Research has revealed that men who carry a from of GST known as GSTP1 are healthy twice as likely as normal to develop prostate cancer at an early age. This discovery would help to identify men at special risk and who could benefit from careful monitoring and preventive measures.

Besides the genetic discoveries already described, researchers at the ICR have already made a number of other important advances in the treatment of and research into the causes of prostate cancer.

Conformal radiotherapy is a new treatment developed at the institute, in which the beam of radiation used to kill cancer tissue is shaped to fit the irregular outline of the tumour. This reduces side-effects on healthy tissue and enables higher doses of radiation to be given.

The researchers at the institute will investigate and develop new hormone therapies for prostate cancer and look for factors in the environment and in diet that may contribute to its incidence.

They will also carry out one of the largest studies of the Occurrence of prostate cancer in families, designed to reveal more genes which may help to cause the condition, and to give clues as to who they have their effects. Dr Peter Rigby, chief executive of the Institute for Cancer Research, said "For too long, prostate cancer has been branded a disease of old men. We must wake up to the fact that men in their 60s or 70s may have another 20 or more years to live, if they can be properly treated."

The institute also has an impressive record in research on testicular cancer, having developed the platinum-based drug which was directly responsible for today's very high cure rate.

The first gene which predisposes to testicular cancer to be discovered was also found at the institute. Now, research will seek out more genes involved in the disease, as well as developing less -radical treatments which will reduce Sideeffects such as sterility. - LPS