Screening for prostate cancer with a blood test can save men’s lives, but the “absolute benefit is small” and many men could face unnecessary treatment and medical complications, according to the most comprehensive study yet.

In a review that analysed six trials involving nearly 800,000 men, screening with the prostate-specific antigen (PSA) test reduced prostate cancer deaths by two for every 1,000 men screened, meaning 500 men must be screened to prevent one death from the disease.

The benefit became apparent as patients were monitored for longer periods, in particular during the European randomized study of screening for prostate cancer (ERSPC), which followed men for 23 years after screening.

“Prostate cancer screening does reduce prostate cancer mortality, although the caveat is that it takes a very extended period of time to realise that benefit,” said Prof Philipp Dahm, a urologist at the University of Minnesota and senior author of the Cochrane review. “This finding is a milestone and I think it will make a difference for a lot of policymakers.”

The UK and many other countries have no formal prostate cancer screening programmes, largely because the PSA test is unreliable. As well as picking up life-threatening tumours, it detects a lot of benign cancers that may never cause problems. This can result in men having radiotherapy, surgery or hormone therapy, putting them at risk of complications such as incontinence and impotence.

The studies in the review did not systematically assess the impact of screening on men’s quality of life, but the ProtecT trial found that between 8% and 47% of men reported problems with urinary or sexual function after radiotherapy or surgery for prostate cancer.

Dr Juan Franco at Heinrich Heine University in Düsseldorf, the first author of the review, said the results were “not a blanket endorsement of universal screening” and stressed the “very real risks” of overdiagnosis and unnecessary treatment. “It’s important to have, ultimately, discussion with patients, and what we call shared decision making,” he said.

Prostate cancer is one of the most common cancers in men. More than 64,000 cases are diagnosed annually in the UK, with one in eight men developing the disease in their lifetime, rising to a quarter of Black men.

Last year, the UK National Screening Committee advised against prostate cancer screening for most men, but recommended a targeted programme for those with BRCA1 and BRCA2 mutations that are linked to more aggressive cancers. Ministers are reviewing the advice.

Dahm said screening made more sense when men were expected to live for at least another 10 to 15 years. “If you have a lot of competing medical comorbidities that are much more likely to limit your life expectancy, you just don’t have to worry about prostate cancer for the most part, because most prostate cancer is slow growing,” he said.

The review also examined recent advances in screening that aim to be more precise and reduce unnecessary biopsies by testing for more prostate-related proteins in the blood and using MRI scans to image the gland. While those look promising, the researchers said it was too early to know if they could save more lives or cause less harm.

David James at Prostate Cancer Research said the review showed how screening reduced deaths from the disease. “It’s also important to recognise how much prostate cancer diagnosis and treatment have evolved since many of these trials began,” he said. “MRI-led diagnostic pathways, more targeted biopsies, active surveillance and newer biomarker tests are all changing the balance between the benefits and harms of screening.”

But Dr Ian Walker at Cancer Research UK said the review highlighted why there was not a widespread UK screening programme. “Whilst this review does highlight that the test could save one to two lives from prostate cancer for every 1,000 men screened, it also shows that around 30 more men could be diagnosed with the disease, many of whom would never have been harmed by their disease and could go on to have unnecessary treatment with long‑term impacts like the loss of bladder control and erectile dysfunction.”

Dr Matthew Hobbs at Prostate Cancer UK said the study showed that PSA screening could save men’s lives “but not nearly enough”.

He said: “More research is needed to plug critical evidence gaps and to find the safest and most effective way to screen men for prostate cancer, ensuring the benefits outweigh the harms.

“In the meantime, we must ensure that all men at risk of prostate cancer can make informed choice about whether or not to have a PSA blood test, so each man can decide what is best for him. This research shows again that this is not a simple decision, and we must be honest with men about the benefits but also about the potential harms.”