New Blood Test Detects 90% of Aggressive Prostate Cancers

A new blood test called Stockholm3 has demonstrated the ability to detect 90% of aggressive prostate cancer cases, significantly outperforming the traditional PSA test, which catches only 74%, according to a large-scale study published in the Annals of Internal Medicine. Researchers at Sweden’s Karolinska Institutet say the breakthrough could fundamentally change how prostate cancer screening is conducted.

The Study

The findings come from a secondary analysis of the STHLM3-MRI randomized trial, one of the largest prostate cancer screening studies ever conducted. Between 2018 and 2020, 12,670 men aged 50 to 74 from Stockholm County, Sweden, were tested with both the standard PSA test and the Stockholm3 blood test, then followed for two years via national cancer registries. During that period, 443 men were diagnosed with clinically significant (aggressive) prostate cancer.

As Karolinska Institutet reported, Stockholm3 detected 90% of these aggressive cases, compared to 74% for PSA — a substantial improvement. The test also had a false-negative rate of just 10%, versus 26% for PSA, meaning it missed far fewer dangerous cancers. Importantly, the false-positive rate remained similar between the two tests: 11% for Stockholm3 versus 10% for PSA, indicating the new test does not lead to more unnecessary follow-up procedures.

Per 1,000 men screened, Stockholm3 detected 31.6 clinically significant prostate cancer cases versus 25.8 for PSA, while missing only 3.4 cases compared to 9.2 missed by PSA.

Why This Matters

Prostate cancer is one of the most common cancers among men worldwide. When aggressive prostate cancer is caught while still confined to the prostate, the five-year survival rate approaches 100%. Yet data from the National Cancer Institute’s SEER database shows that metastatic prostate cancer has risen over the past decade, suggesting that current screening methods are failing to catch dangerous cases early enough.

The PSA test has been the standard since the 1990s, but it has well-documented limitations. As study co-author Dr. Hari Vigneswaran, chief medical officer of A3P Biomedical, told Fox News Digital, PSA “leads to invasive and costly follow-up testing, contributes to over-diagnosis of non-aggressive cancers and, most importantly, it misses a substantial share of aggressive disease.”

How Stockholm3 Works

Developed by researchers at Karolinska Institutet, Stockholm3 is a multicomponent blood-based biomarker test that combines PSA with additional plasma protein biomarkers, a polygenic risk score, and clinical variables such as age into a single algorithm. The test estimates a man’s risk of aggressive prostate cancer, providing a more comprehensive risk assessment than PSA alone.

Previous STHLM3-MRI results showed that combining Stockholm3 with MRI-targeted biopsy decreased overdetection of non-aggressive cancers by 69% while maintaining detection of clinically significant cancers, and reduced the number of MRIs needed by one-third.

Expert Reaction

Lead researcher Thorgerdur Palsdottir, PhD, of the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet, emphasized the test’s precision: “The major challenge in prostate cancer screening is not just to find more cancer cases, but to identify the cancers that are truly dangerous. Our results show that Stockholm3 identifies significantly more aggressive cancer cases than PSA, without increasing the number of unnecessary follow-ups.”

She added: “These results point toward a potential change in how prostate cancer screening can be conducted. A more precise blood test could enable earlier detection of aggressive disease while reducing the number of unnecessary follow-up examinations and procedures.”

Limitations and Next Steps

Despite the promising results, Stockholm3 is not yet available in the United States. It is currently classified as an investigational device, and A3P Biomedical plans to seek FDA approval for routine screening, which will require generating U.S.-specific clinical data. The test currently costs between $550 and $750 in European markets, significantly more than the inexpensive PSA test.

Study authors also noted that the follow-up period was limited to two years, and longer-term data on mortality and cost-effectiveness are needed. As they wrote in the Annals of Internal Medicine, “If confirmed, integrating Stockholm3 into screening pathways may improve the efficiency and clinical utility of prostate cancer screening programs.”

A biopsy remains the gold standard for confirming a prostate cancer diagnosis. However, if Stockholm3 gains regulatory approval, it could transform screening protocols worldwide — offering men a more accurate, less invasive first step toward catching the most dangerous forms of the disease while they are still curable.

This article is based on research published in the Annals of Internal Medicine and reported by MedPage Today and HealthDay.