Prostate screening using PSA 'would overdiagnose one in three cancers'
By Lilian Anekwe
The introduction of PSA testing could lead to as many as one in three prostate cancers being overdiagnosed, new research suggests.
A UK study shows that screening for prostate cancer using PSA testing – which is currently under consideration by the National Screening Committee – would lead to a substantial number of tumours being detected at an earlier stage.
But researchers warned that up to a third of prostate cancers would be overdiagnosed, and that there would be a lengthy delay of more than ten years between tumours being detected, and men displaying any symptoms.
A study of 43,842 men aged 50 to 69 given PSA tests detected 1,544 prostate cancers. 10% of patients aged 50 to 59 were overdiagnosed, which increased to 31% in the 60 to 69 age group.
The average length of time during which tumours did not produce symptoms having been detected by PSA testing was 11.3 years in the 50 to 59 group and 12.6 years in the 60-69 group.
However, after adjusting for overdiagnosis, two-yearly PSA testing might still result in a reduction in advanced stage prostate cancer of up to 54 per cent. The study is published in the April issue of the British Journal of Cancer.
Dr Nora Pashayan, a researcher in public health at the University of Cambridge and lead researcher, said: ‘Our results indicate a benefit of screening to reduce the risk of advanced stage prostate cancer. However, this is limited by overdiagnosis.
‘Any screening strategy should take account of the potential benefits and harms of screening. A valuable target for future research would be to estimate the benefit of screening at different ages'
Professor Peter Johnson, chief clinician at Cancer Research UK, said: "We need to continue to search out markers that will tell us if a prostate cancer is aggressive or not so that we know which ones to treat and which ones are best to monitor.
‘While a recent study shows that PSA tests can detect very early prostate cancer and may reduce deaths from the disease by up to 20 per cent, even in large trials it has been difficult to prove the real impact of PSA screening.
‘The important thing is that any men that think they might be experiencing symptoms such as difficulty urinating should contact their GP as soon as possible to rule out cancer.'