The breakthrough PSA blood test for prostate cancer can miss aggressive bouts of the disease and overdiagnose cases, a major study has found.
It also found that the Prostate-Specific Antigen Test was only having a small impact of reducing deaths.
“The key takeaway is that the small reduction in prostate cancer deaths by using the test to screen healthy men does not outweigh the potential harms,” Prof Richard Martin, lead author and Cancer Research UK scientist at the University of Bristol, said.
The CAP trial, published in the Journal of the American Medical Association, involved more than 400,000 men aged 50-69, and just under half of them received a single invitation PSA test as part of the trial.
It was the largest study investigating a single invitation PSA blood test to screen for prostate cancer.
Last week, a different study forecast prostate cancer cases to double between 2020 and 2040, as populations age and life expectancy increases worldwide.
In the CAP trial, researchers measured the effectiveness of the PSA test for hundreds of thousands of men over 15 years.
“This results in some men going on to have invasive treatment that they don’t need, many years earlier than without screening, and the test is also failing to spot some cancers that do need to be treated,” Prof Martin said.
“We need to find better ways to spot aggressive prostate cancers, so we can treat them early.”
After following patients over 15 years the study found only a small difference in the number of men who died from prostate cancer.
Almost seven men out of every 1,000 in the group invited for screening had died from prostate cancer, compared with nearly eight men out of every 1,000 in the group who had not been invited for screening.
The results also showed that about one in six cancers found by the single PSA screening were overdiagnosed.
Problems with overdiagnosis
Overdiagnosis of prostate cancer is a main worry in using PSA tests for early detection, the Cancer Research UK charity said.
Overdiagnosis can result in the unnecessary treatment of cancers that would not have caused any harm and can have a negative psychological impact. The treatment of prostate cancer may also cause physical side effects.
Prostate cancer is the second-biggest cancer killer of men in the UK, causing 12,000 deaths a year.
Naser Turabi, director of evidence and implementation at Cancer Research UK, said: “The evidence shows that using a single invitation for a PSA test for a prostate cancer screening programme is likely to do more harm than good for men.
“We are funding research to help us find ways of diagnosing the disease early to reduce mortality, and we have trials taking place to find the best treatment for men with prostate cancer.”
Early prostate cancer usually has no symptoms, making early detection a challenge.
Cancer Research UK is funding more trials and research into prostate cancer.
It is looking to speed up diagnosis for men with aggressive disease with new blood, urine or genetic tests so they can start treatment sooner.
