Although the UK prostate cancer charities have been publicising the need for early detention and treatment of this disease during Prostate Cancer Awareness month, the manner of screening for this disease and, in particular, the use of Prostate Specific Antigen (PSA) has come under increasing criticism with the allegation that it can lead to over-diagnosis.
When running for president of the United States, Mayor Giuliani claimed that he was lucky to be treated for prostate cancer in the US because his chance of surviving was 82% whereas in England under the NHS it was 44%. The mortality rate is, in fact, about the same in both countries but, because of the wider use of PSA screening in the US, men become aware earlier that they may have a cancer.
As a result of this earlier knowledge, the survival rate - the time between diagnosis and death - is longer but this has nothing to do with better treatment. In many cases, a positive result will not lead to a life-threatening disease but that diagnosis may result in unnecessary treatment and damage the man’s quality of life.
The balance is to detect the disease early to minimise deaths but to avoid unnecessary treatment due to over diagnosis. The British Medical Journal recently commented that:
- The most effective way to reduce the recorded incidence of prostate cancer (the statistical proportion of those with cancer) is, ironically, to reduce PSA testing or to raise the threshold that defines abnormalities.
- Prostate cancer screened by PSA blood results leads to, at best, a small reduction in prostate cancer deaths but also to considerable diagnostic and treatment-related harm.
- Most men with prostate cancer detected by PSA screening will have tumours that will not cause health problems but almost all of them will undergo early treatment that is not necessary and mostly harmful.
- A positive PSA result will often lead to a biopsy to check the diagnosis which, in most cases, will be unnecessary but, in itself, carries a risk of harm.
Tim Wright, senior associate in the Penningtons Manches’ clinical negligence team, says: “The current clinical thinking is to avoid early intervention following a positive result which can cause serious collateral harm. The important step to take on early diagnosis is regular observation as this can help most men with early stage prostate cancer, whether detected by PSA screening or otherwise.
“Not only can over-diagnosis lead to unnecessary intervention and concern for those involved but is a waste of resources in an already over-stretched health service.”