There are fears that widespread introduction of the Prostate Specific Antigen (PSA) test could lead to many unnecessary operations.

Speaking at the European Cancer Conference in Lisbon on Thursday, a leading prostate specialist from the Netherlands, Professor Fritz Schroder, said it was "unethical" to apply the test without first making sure men understood the implications of a positive, or negative, result.

The PSA test looks for chemical markers in the blood - high levels suggest that the man may have a prostate cancer.

However, two-thirds of men with elevated PSA levels don't actually have the disease, as it could mean they have a simple infection or inflammation of the prostate.

Powerful, early diagnostic tests cannot be withheld from well-informed men. The accent here, however, has to be on well-informed

Professor Fritz Schroder

In addition, some men who have completely normal PSA readings do turn out to have cancer - so it is certainly not a failsafe.

In the US, widespread PSA testing has vastly increased the number of prostate cancers detected, but very many of these are slow-growing tumours in elderly men, and unlikely to pose a direct threat to life.

Nevertheless, many men went ahead with potentially risky surgery to remove the prostate, or radiotherapy treatment, both of which carry a significant risk of leaving the patient impotent, incontinent, or both.

Vulnerable nerves

This is because the prostate gland, lying just under the bladder, is close to a number of tissues important in continence and sexual function - it is difficult for surgeons or radiologists to avoid damaging these at the same time.

One study following prostate removal surgery patients in the US found that 60% were impotent 18 months after surgery, 8% had complete urinary incontinence, and 40% had occasional genitourinary problems of one sort or the other.

Professor Schroder told the conference: "Powerful, early diagnostic tests cannot be withheld from well-informed men.

"The accent here, however, has to be on well-informed."

In many parts of the world, doctors will often advise patients who are found to have a prostate cancer to wait and see how aggressive the tumour is before opting for prostate removal or radiotherapy.

This "watchful waiting" involves check-ups every few months to see if the tumour has increased in size.