March 2014 is Prostate Cancer Awareness month and much is being done by charities across the UK to publicise the need for early detection and treatment of the disease. However, 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 this can lead to over diagnosis.
When running for President of the United States, former Mayor of New York City, Rudy Giuliani, no doubt attacking President Obama’s attempt to make medical care in America work for all, made the claim 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, due to the wider use of PSA screening, men in the US often become aware earlier that they may have a cancer. Simply because of this earlier knowledge, the survival rate (the time between diagnosis and death) is longer but this has nothing to do with better treatment. Although in many cases a positive result will not lead to life threatening disease, it can lead to unnecessary treatment and damage to the man’s quality of life.
The balance is to detect the disease early enough to minimise deaths whilst avoiding unnecessary treatment due to over diagnosis. The British Medical Journal recently commented as follows:
- 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 most 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 will undergo early treatment that is not necessary and mostly harmful.
- Notably 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.
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. Regular observation 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.