New Blood Test Detects 90% of Aggressive Prostate Cancer Cases, Outperforming Standard PSA Screening
A blood test called Stockholm3 detected 90% of aggressive prostate cancer cases in a clinical trial spanning more than 12,000 men, surpassing the traditional prostate-specific antigen test, which caught 74%, according to a study published in the Annals of Internal Medicine. Researchers at the Karolinska Institutet in Sweden said the results suggest a potential shift in how prostate cancer screening is conducted, with Stockholm3 identifying significantly more dangerous cases without raising the rate of unnecessary follow-up procedures.
A blood test called Stockholm3 detected 90% of aggressive prostate cancer cases in a clinical trial spanning more than 12,000 men, surpassing the traditional prostate-specific antigen test, which caught 74%, according to a study published in the Annals of Internal Medicine. Researchers at the Karolinska Institutet in Sweden said the results suggest a potential shift in how prostate cancer screening is conducted, with Stockholm3 identifying significantly more dangerous cases without raising the rate of unnecessary follow-up procedures.
What the Trial Found
The study followed men aged 50 to 74 — mostly Swedish or European — for two years, with all participants receiving both the PSA and Stockholm3 tests. Of the 443 men diagnosed with aggressive prostate cancer during the follow-up period, Stockholm3 missed significantly fewer serious cases than PSA did. Critically, the number of men incorrectly flagged as high-risk was similar across both tests, meaning Stockholm3's gains in sensitivity did not come at the cost of more false positives.
Thorgerdur Palsdottir, a researcher at Karolinska Institutet's Department of Medical Epidemiology and Biostatistics, said one of the core challenges in prostate cancer care is distinguishing which cases are "truly dangerous." Stockholm3, she said, identifies significantly more aggressive cancers than PSA without increasing unnecessary follow-ups, adding that a more precise test could enable earlier detection while reducing unnecessary examinations and procedures.
The Case Against the PSA Standard
PSA has been the benchmark for prostate cancer screening since the 1990s despite well-documented limitations, according to Hari Vigneswaran, MD, chief medical officer of A3P Biomedical, the maker of Stockholm3, who served as a study co-author. Vigneswaran said the PSA test leads to invasive and costly follow-up testing, contributes to over-diagnosis of non-aggressive cancers, and misses a substantial share of aggressive disease. Data from the National Cancer Institute's SEER database show metastatic prostate cancer has risen over the past decade, which Vigneswaran said indicates that early detection of aggressive, curable disease has not improved under current screening methods. When aggressive prostate cancer is caught while still confined to the prostate, the five-year survival rate is close to 100%, he noted.
Regulatory Status and Next Steps
Stockholm3 remains an investigational device and is not currently available for sale in the United States. A3P Biomedical plans to seek FDA approval for routine screening use and said it will generate supporting evidence, including U.S.-specific data, to advance that regulatory pathway. A biopsy remains the gold standard for confirming a prostate cancer diagnosis; Stockholm3 estimates risk but does not replace that step. The company and Karolinska researchers said the test could reduce the need for unnecessary MRIs and biopsies if it clears regulatory review.