Screening for prostate cancer likely to reduce deaths but risks remain – review
Screening men for prostate cancer using a blood test is likely to reduce deaths from the disease, a new review has found, although experts stressed there are still risks around overdiagnosis and overtreatment.
The findings of the analysis, which included almost 800,000 patients, may “support a conversation” around screening using the prostate specific antigen (PSA) test, researchers said, although they described the test as “imperfect”.
Cancer Research UK also said the test is “not effective enough”.
Prostate cancer is the most common cancer in the UK, with more than 64,000 men diagnosed every year, although screening for the disease remains controversial.
Some experts argue the PSA test – which measures the levels of a protein produced by the prostate – is unreliable and can lead to overdiagnosis.
In some cases, men with a high PSA level may not have cancer while those with a normal level may have the disease.
The test can also lead to the discovery of harmless tumours, resulting in unnecessary treatment with the risk of side-effects such as incontinence and erectile dysfunction.
Now, in a major new Cochrane review, experts have analysed the results of six trials involving 789,086 patients, five of which shaped the findings.
The men involved spanned from 45 to 80, but were primarily aged between 50 and 70.
The analysis found that, without screening, 16 men per 1,000 would die from prostate cancer.
Screening reduced this by two deaths, to 14 per 1,000 men.
The latest findings are a shift from a previous Cochrane review in 2013, which found that screening did not significantly reduce deaths.
The trials included in the latest research did not look at impacts on quality of life, such as complications from biopsies, sexual dysfunction and urinary problems.
However, first author Dr Juan Franco, of Heinrich Heine University Dusseldorf, highlights other studies which estimate the overdiagnosis rate to be between 20% to 50% for prostate cancer.
He described the PSA as “an imperfect test” and stressed there are “many kinds” of prostate cancer.
“There are very aggressive kinds that can cause death, but there’s also very benign forms that take the whole life to grow and perhaps never cause any problems for men,” Dr Franco said.
“That is what we call overdiagnosis and that is another side effect related to the screening.”
He added that the test can “detect a lot of benign cancers in men that ultimately would have never had caused any problems and those men who received the diagnosis may receive treatment”.
“That could be radiation, surgery, hormone therapy and they may suffer the side effects of those treatments,” he said.
However, senior author Dr Philipp Dahm, of the University of Minnesota, said the findings “support a conversation about PSA screening”.
“With new data now available, we can now say with moderate certainty that PSA screening reduces prostate cancer deaths in men with a sufficient life expectancy,” he said.
“This suggests that for the right patient – someone who is well-informed, has a good life expectancy and understands the full implications of screening – there is now a reasonable evidence base to support a conversation about PSA screening.
“This represents an important change in the evidence for future guideline developers and policy-makers to consider.”
Dr Dahm added: “I see a lot of patients that come to me with an elevated PSA, or see a lot of patients in whom prostate cancer has been diagnosed, and then I’m in charge in advising them of treatment.
“I don’t want to take away from what guideline developers will say, but with these results I think more guideline developers may recommend prostate cancer screening for men that have certain characteristics, the most important one being that they have a long life expectancy.”
Dr Franco said: “We want to be clear that this is not a blanket endorsement of universal screening.
“The decision should always be made between a patient and their doctor, with a full understanding of both the potential benefits and the very real risks of overdiagnosis and unnecessary treatment.”
There is currently no screening programme for prostate cancer in the UK, although men over 50 can request a PSA test from their GP.
In November, the UK National Screening Committee (UKNSC) said it would not recommend screening using the PSA test because it “is likely to cause more harm than good”.
It only recommended that men with BRCA1 and BRCA2 genetic mutations – which puts them at far higher risk of prostate cancer – should be screened every two years, between the ages of 45 and 61.
Reacting to the findings of the Cochrane review, Dr Ian Walker, executive director of policy at Cancer Research UK, said: “This is the most comprehensive study of prostate cancer screening to date and highlights why there isn’t currently a widespread screening programme in the UK.
“Unfortunately, the test currently used to detect prostate cancer is not effective enough.
“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.
“The study shows the complex challenge of balancing benefits against unintended harms when informing recommendations around screening.”
The study comes after the first men were tested as part of a landmark study into prostate cancer screening.
The Transform trial, funded by Prostate Cancer UK and the National Institute for Health and Care Research, will compare multiple methods, such as genetic tests or 10-minute MRI scans, to find the safest and most cost-effective way to screen men for the disease.
Published: by Radio NewsHub