Largest trial ever to investigate prostate cancer screening

Inviting men with no symptoms to a one off PSA test for prostate cancer does not save lives, according to results from the largest ever trial conducted by Cancer Research UK-funded scientists based at the University of Bristol.

The findings are published in the Journal of the American Medical Association (JAMA).

Researchers at the Universities of Bristol and Oxford found that testing asymptomatic men with PSA detects some disease that would be unlikely to cause any harm but also misses some aggressive and lethal prostate cancers. The University of Bristol reports this highlights the flaws of a single PSA test as a way to screen for prostate cancer, and shows the need to find more accurate ways to diagnose cancers that need to be treated.

Professor Richard Martin, lead author and Cancer Research UK scientist in the Bristol Medical School: PHS at the University of Bristol, said “Our large study has shed light on a highly debated issue. We found that offering a single PSA test to men with no symptoms of prostate cancer does not save lives after an average follow-up of ten years. The results highlight the multitude of issues the PSA test raises – causing unnecessary anxiety and treatment by diagnosing prostate cancer in men who would never have been affected by it and failing to detect dangerous prostate cancers. Cancer Research UK is funding work that will allow us to follow the men for at least a further five years to see whether there is any longer-term benefit on reducing prostate cancer deaths.”

Dr Emma Turner, a Cancer Research UK scientist at the University of Bristol and co-author of the study, said “Prostate cancer is the second most common cause of cancer death in men in the UK. We now need to find better ways of diagnosing aggressive prostate cancers that need to be treated early.”

The CAP Trial, which spanned almost six hundred GP practices in the UK and included more than four hundred thousand men aged between fifty and sixty nine, is the largest trial ever to investigate prostate cancer screening. The trial compared 189,386 men who were invited to have a one off PSA test with 219,439 men who were not invited for screening.

After an average of ten years follow up, there were 8,054 (4.3%) prostate cancers in the screened group and 7,853 (3.6%) cases in the control group. Crucially, both groups had the same percentage of men dying from prostate cancer (0.29%).

There is no national screening programme for prostate cancer in the UK, but men over fifty can ask their GP for a PSA test.

More than eleven thousand men die of prostate cancer each year in the UK. While some prostate cancers are aggressive and lethal, others are clinically insignificant and will never lead to any harm or death if left undetected. Ideally, aggressive prostate cancers need to be identified and treated as early as possible. But finding a cancer that would never have caused men harm during their lifetime can have a serious impact on quality of life, including the worry of a cancer diagnosis, the possibility of infection following a biopsy and impotence and incontinence following treatment.

Dr Richard Roope, Cancer Research UK’s GP expert, said “The PSA test is a blunt tool missing the subtleties of the disease and causing men harm. This trial illustrates that we need to develop more accurate tools if we want to save men’s lives. Cancer Research UK’s hunt for finding early stages of aggressive prostate cancer is not over. For example, we’re funding research into faulty genes which make some men more likely to develop prostate cancer and studying how these genes could help doctors to identify patients who are more at risk.”

Cancer Research UK don’t recommend that GPs routinely offer the PSA test to men without symptoms. If men are worried about prostate cancer they should have a full discussion with their GP.

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