Stockholm3, a multivariable blood-based prostate cancer screening test, detected more than twice as many clinically significant prostate cancers as age-based prostate-specific antigen (PSA) screening in a population-based study of 12,670 men published in Annals of Internal Medicine.
Researchers analyzed data from the STHLM3-MRI screening trial involving men aged 50 to 74 years in the Stockholm region of Sweden. The study compared the performance of Stockholm3 – a test that combines PSA measurements with genetic, protein, and clinical risk factors – with conventional PSA screening for identifying clinically significant prostate cancer, defined as grade group 2 or higher.
During 2 years of follow-up, 443 men were diagnosed with clinically significant prostate cancer. Stockholm3 identified 400 out of 443 men with cancer (90 percent), while PSA ≥3 ng/ml identified 327 (74 percent) and PSA ≥4 ng/ml identified 231 (52 percent). The false-positive rates were similar for Stockholm3 and PSA ≥3 ng/ml (11 percent vs 10 percent) while PSA ≥4 ng/ml had a false-positive rate of 5 percent.
The higher detection rate came with a trade-off. Stockholm3 referred more men for additional diagnostic assessment and had lower specificity than age-based PSA thresholds in the population analysis reported by the study investigators. However, decision-curve analyses indicated a higher overall clinical benefit across a range of biopsy decision thresholds.
The study was a secondary analysis of the baseline screening round of the prospective STHLM3-MRI randomized trial. Men with abnormal screening results underwent either systematic biopsy or magnetic resonance imaging with targeted and systematic biopsies, depending on random assignment.
The publication comes as the UK continues to evaluate prostate cancer screening strategies. The UK National Screening Committee recently recommended targeted screening for certain men at elevated genetic risk but stopped short of endorsing population-wide screening.
David James, Director of Patient Projects and Influencing at Prostate Cancer Research, said, "This study underlines how more sophisticated, risk-based tests could improve detection of clinically significant prostate cancer while reducing unnecessary procedures. As new evidence like this emerges, it must be reflected in how prostate cancer screening is assessed. This is one of the first real opportunities for the UK National Screening Committee to act on its commitment to a more updatable approach to modelling by incorporating these data and updating its outputs and recommendation accordingly."
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