Prostate cancer screening modestly reduces deaths, study finds

Prostate cancer is the second most common cancer in men globally. Early detection through screening has long been debated, as experts are divided on whether the benefits outweigh the risks of overdiagnosis and overtreatment.A new Cochrane review has found that screening for prostate cancer with a blood test can likely reduce the risk of dying from the disease. This is a significant shift from the previous review, which did not find sufficient evidence that screening reduced prostate cancer deaths. The findings are published in the Cochrane Database of Systematic Reviews.In the review, the researchers analysed six trials involving 800,000 participants across Europe and North America. They found that screening with the PSA (prostate-specific antigen) blood test reduces prostate cancer deaths by approximately 2 for every 1,000 men screened. This means one prostate cancer death can be prevented if 500 men are screened. These mortality data come from a major trial that followed 162,241 men for 23 years.“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. 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 Philipp Dahm, senior author from the University of Minnesota, said in a release.The studies in the review, however, did not assess the impacts on quality of life, such as complications from biopsies, sexual dysfunction and urinary problems.While the PSA blood test for prostate cancer screening can make a meaningful difference, the risk of overdiagnosis is not eliminated. The screening detected about 30% more prostate cancers overall, at an early stage. Roughly 36 extra cancers were diagnosed per thousand men screened, for every 1–2 deaths prevented. These tests can detect low-grade cancers that may never have caused symptoms or harm during a man's lifetime. This means such identification can cause anxiety and lead to unnecessarily aggressive treatment.“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,” first author Dr Juan Franco from Heinrich Heine University Düsseldorf said.The previous version of this review found that screening did not significantly reduce prostate cancer deaths. It was based on a meta-analysis of five randomised controlled trials. This uncertainty led to delays in, or the avoidance of, the introduction of national screening programmes in several countries.The authors of this review emphasised that the modest benefits now observed are not due to a change in the underlying evidence, but because the trials have now followed participants for long enough to detect a mortality benefit that was previously too early to observe.“The landscape has changed considerably since our 2013 review. Not only do we have stronger long-term evidence on mortality, but the tools available to reduce the harms of screening, such as MRI and active surveillance, have also advanced significantly,” Dr Franco added.This review also looked at new screening approaches, such as combining PSA tests, kallikrein blood tests and MRI scans, to improve accuracy. This approach also reduces unnecessary biopsies. MRI and active surveillance approaches help to detect low-risk cancers that do not need aggressive treatment. For patients and doctors considering prostate cancer screening, the evidence now supports an informed discussion. However, this should remain individualised, weighing both the modest mortality benefits and the very real risks of overdiagnosis and unnecessary treatment.