Those resistant to hormonal therapy could benefit from new treatment

More research is needed before confident claims can be made, writes Dr Muiris Houston

THE MAIN risk factor for prostate cancer is advanced age, with 80 per cent of cases occurring in men over the age of 65. In many instances, the cancer is non-aggressive, so that the lifetime risk of dying from prostate cancer is 3 per cent.

The prostate gland lies just under the bladder and surrounds the urethra; it secretes fluid that nourishes sperm and provides most of the volume of semen.

Among the tests for prostate cancer is prostate specific antigen (PSA). An elevated blood PSA level may also be caused by simple enlargement of the gland, infection or inflammation. So it is necessary to take a biopsy of the gland to see if cancer cells are present before a diagnosis can be made. The likely course of the cancer is then estimated by calculating the volume of the tumour, its aggressiveness and how far it has spread.

The main treatments for the disease are surgery, a localised form of radiotherapy called brachytherapy, and treatment to reduce the amount of testosterone, the hormone that prostate cancer feeds off. Called androgen deprivation therapy, the male hormone is blocked by means of castration or by using drugs.

Depriving the body of androgens (testosterone) may slow the spread of prostate cancer. But some men are either resistant to hormonal therapy or its effects wear off over time.

It is this subset of patients that may benefit from the new drug, abiraterone acetate.

However, the trial reported on yesterday was on a very small number of patients; it was unrandomised, which means both the doctors and the patients knew who was being treated and there was no comparison with a group of men given a placebo drug. And while two-thirds of the 21 men treated had a significant lowering of PSA, this may not translate into better survival when more robust research is carried out.

The least we need to see before we can claim a real breakthrough with this drug is a major improvement in cancer symptoms for a minimum of four to six months following randomised clinical trials.

© 2008 The Irish Times

This article appears in the print edition of the Irish Times