Experts have warned that prostate cancer screening is likely to do more harm than good after a 15-year trial showed one in six cases flagged were inaccurate.
The largest study to date investigating the PSA (Prostate specific antigen) blood test, used as a screening tool in some European countries, has found that the test has a small effect in reducing deaths but also leads to alarming levels of overdiagnosis.
In some cases, it missed early detection of some aggressive cancers.
Researchers from the universities of Bristol, Oxford and Cambridge invited more than 400,000 men aged 50 to 69 to be screened, with just over half of them having a PSA test.
After 15 years of follow-up, about seven in every 1,000 men in the group invited for screening had died of prostate cancer, while about eight in every 1,000 men who were not tested had died of prostate cancer.
The results of the trial show that an estimated one in six cancers found with a single PSA scan are overdiagnosed, leading to unnecessary treatment of tumors that will not cause any harm to the person’s life.
Treatment of prostate cancer can cause physical side effects, such as the possibility of infection after biopsy, erectile dysfunction, and bladder and bowel problems.
Lead author and Cancer Research UK scientist Professor Richard Martin, from the University of Bristol, said: “The key conclusion is that the small reduction in prostate cancer deaths by using the test to screen healthy men does not outweigh the potential harms.
‘Some men get treatment they don’t need’
“This leads some men to seek invasive treatment they don’t need years before they are screened, and the test also fails to detect some cancers that need to be treated.
“We need to find better ways to detect aggressive prostate cancers so we can treat them early.”
Prostate cancer is the second biggest cancer killer among men in the UK, causing 12,000 deaths a year.
It is the most common cancer for which there is no screening program in the UK, although it often has no symptoms until it spreads and becomes untreatable.
The UK National Screening Committee (NSC), which reviews the evidence on screening programmes, does not currently recommend prostate cancer screening as it is unclear whether the benefits outweigh the harms.
Cancer Research UK Practitioner and Chief Physician for the Lancashire and South Cumbria Cancer Alliance Dr. Neil Smith said: “Given prostate cancer causes 12,000 deaths in the UK every year, we completely understand why men want to know whether they have the disease when they have no symptoms.
“However, this research highlights that PSA testing for early detection may do more harm than good – it is not accurate enough and could lead to some men being subjected to tests and treatments they do not need.
“You know your body best; Therefore, if you notice any unusual changes, contact your doctor. “It probably won’t be cancer, but if it is, catching it early means treatment is more likely to be successful.”
Early prostate cancer often has no symptoms, so early diagnosis is difficult.
Last year Prostate Cancer UK launched the £42 million Transform trial, which will examine hundreds of thousands of men to see whether MRI scans can do a better job of detecting disease early.
Other research, such as the Stampede study, aims to find the best treatment to further improve survival and quality of life in men with advanced prostate cancer.
Director of Prostate Cancer Research UK, Dr. Matthew Hobbs said: “A previous trial showed that screening with PSA blood tests reduced deaths from prostate cancer, but also missed important cancers and harmed men given treatment or a biopsy that they did not need.”
“The results of the UK CaP study are extremely important because they support these findings.
“The number of men screened in both studies who died of prostate cancer makes clear that the imperative now is to develop, test and prove new ways to diagnose prostate cancer that detect aggressive cancers missed by PSA tests and even reduce potential harm.” further.”
In a separate study, researchers found that reducing the length of MRI scans for prostate cancer by one-third would make scans cheaper and more accessible without hampering accuracy.
Clinicians recommend MRI scanning, which is performed in three stages, to patients suspected of having prostate cancer.
The final step involves injecting the patient with contrast dye, which helps improve the images from the scan.
Researchers from University College London (UCL) and University College London Hospitals NHS Foundation Trust said removing this step would reduce costs and make MRIs available to more men.
But they warned that it was “vital” that scans were of “optimal diagnostic quality” if this approach was adopted.