A Swedish study suggests a new blood test called Stockholm3 spots dangerous prostate cancers more reliably than the long-used PSA check, potentially catching more curable cases early while trimming unnecessary follow-ups and procedures; the test found 90% of aggressive cases versus 74% for PSA in a trial of more than 12,000 men, but Stockholm3 is still investigational and not yet available in the U.S.
The researchers enrolled men aged 50 to 74, mostly from Sweden and other parts of Europe, and tracked them for two years to compare how the two tests performed in the real world. During that period, 443 participants were diagnosed with aggressive prostate cancer, giving the team a clear set of outcomes to evaluate. The trial was driven by a desire to separate the cancers that truly need treatment from those that do not. That distinction is the core challenge the investigators targeted.
Stockholm3 flagged a larger share of the aggressive tumors: it picked up 90% of the cases classified as dangerous, while PSA detected 74%. Beyond raw sensitivity, Stockholm3 missed “significantly fewer” serious cancer cases, and the rate of men incorrectly labeled high-risk was similar for both tests. In short, Stockholm3 appeared to improve detection of the cancers that matter without boosting false alarms.
One of the study authors highlighted the difficulty doctors face in deciding which tumors require intervention and which can be safely watched. She wrote that one of the major challenges in prostate cancer is being able to identify the cases that are “truly dangerous.” She also said, “Our results show that Stockholm3 identifies significantly more aggressive cancer cases than PSA, without increasing the number of unnecessary follow-ups.”
Another co-author who is involved with the company that developed the test noted that PSA has been the standard screening tool since the 1990s despite known issues. He warned that the older approach “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.” The implication is clear: a better screening test could tighten the net around cancers that need treatment and loosen it around those that do not.
Finding aggressive tumors when they are still confined to the prostate is crucial because survival rates are far higher at that stage. When aggressive prostate cancer is found while still confined in the prostate, the five-year survival rate is close to 100%, which highlights the importance of early detection. At the same time, registry numbers show that metastatic prostate cancer has been increasing over the last decade, a trend that suggests current screening strategies are missing some dangerous cases.
Experts stress that the goal of screening should be narrowly focused. “The goal of screening is to find the cancers that need treatment while they are still curable, without raising the number of men who screen positive but don’t have aggressive disease,” he said. Stockholm3 could help meet that aim by reducing unnecessary MRIs and biopsies while honing in on the tumors that actually require care.
There are caveats. Stockholm3 is an investigational device and is not yet for sale in the United States, so patients and clinicians in the U.S. cannot rely on it today. The test provides an estimate of a man’s risk for aggressive prostate cancer, but a biopsy remains the definitive method to confirm a diagnosis. The company says it will seek FDA approval and will collect additional data, including studies in U.S. populations, to support broader use.
