Researcher claims disease overtreated

Many men in New Zealand are suffering side effects after radiotherapy and surgery for prostate cancer which would never have killed them, and a screening programme would increase this, University of Otago public health researcher Dr Brian Cox says.

He was commenting on the recent announcement by chairman of the Health Committee Dr Paul Hutchison that the committee will conduct an inquiry into optimal screening (or early detection) and treatment of prostate cancer.

Dr Cox is concerned there is already considerable over treatment of men for this disease with very little evidence of any reduction in deaths from it.

The issue of prostate screening has been controversial, with some proponents of it suggesting that the disease has received less attention than women's diseases such as breast and cervical cancer both of which have screening programmes.

This argument does not wash with Dr Cox, who says there is still no evidence that a screening programme would be beneficial.

"Were not withholding something from them which does work."

It did not make sense to do something which would increase peoples risk "if you are offering something which has a considerable hazard, you have really added to their problems".

The difficulty was that the commonly used prostate specific antigen test (PSA) led to over-diagnosis of cancers and over treatment.

About 30% of men over 50 had a small tumour on their prostate which, when studied under a microscope was indistinguishable from cancer.

A vast majority of these tumours did not appear to become a clinical disease or even cause symptoms.

Research into randomised trials using PSA for screening showed that the over-diagnosis of cancers could be as high as 50%.

Men were undergoing radical prostatectomy or radiotherapy which could result in chronic incontinence (urinary or faecal), impotence, or in some instances, death, he said.

Dr Cox estimates that about 2000 cases of prostate cancer are detected by PSA testing a year in New Zealand and about half of them would never become clinically relevant.

Results of a recent European randomised trial showed 1480 men would need to be screened and 48 additional cases of prostate cancer treated for each death prevented over a 10-year period.

About half of those additional cases would be receiving treatment for something which would not have become clinical prostate cancer in their lifetime, and about four of them would have chronic incontinence or impotence.

Dr Cox said he was looking forward to seeing the terms of reference for the inquiry and hoped that the committee wanted to seriously consider all the information and not push through a political agenda.

Dr Hutchison said he was aware the situation was controversial and some clinicians were frustrated about the current guidelines, particularly as they considered there was benefit in testing those considered at higher risk.

Recent research findings were another reason for his decision to look at the situation again.

He was anxious to get as much factual information as he could.

Prostate cancer in NZ

583 deaths from prostate cancer in 2004.

2693 new registrations in 2004.

Death rate 1995-2002, 18-20 per 100,000; dropped slightly to 16.6 by 2004.

Two-thirds of deaths in men 75 or older.

PSA test

Prostate specific antigen test measures the level of this in the blood.

Levels can be raised by urinary or prostate infection, enlarged prostate, prostate cancer or other reasons including recent ejaculation.

There is no absolute PSA level that detects a cancer.

Screening

Using PSA or digital rectal examination for men without symptoms -

Ruled out by National Health Committee in 2004.

Potential for benefit did not outweigh harm.

There was no suitable test.

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