Blood Test Detects More High-Risk Prostate Cancers Than PSA

Prostate cancer is one of the most common malignancies in men, and screening often struggles to distinguish indolent tumors from clinically significant disease. Prostate-specific antigen (PSA) testing can miss aggressive cancers while triggering unnecessary workups. More accurate blood-based risk assessment could improve triage and reduce avoidable procedures. A new study shows that the Stockholm3 blood test detected more high-risk prostate cancers than PSA in a large, population-based cohort.

Karolinska Institutet evaluated the Stockholm3 blood test against prostate-specific antigen (PSA) testing. The blood-based Stockholm3 test identified significantly more aggressive prostate cancers than traditional PSA without subjecting more men to unnecessary testing. The findings were published in Annals of Internal Medicine on June 23, 2026.

In a population-based study of 12,670 men aged 50–74 years, Stockholm3 detected 90% of aggressive cancer cases compared with 74% for PSA. The work draws on the STHLM3–MRI study framework. All participants underwent both tests and were followed for two years through national cancer registries to ascertain cancers missed at initial screening.

During follow-up, 443 men were diagnosed with clinically significant, or aggressive, prostate cancer. Stockholm3 missed significantly fewer serious cases than PSA, while the proportion of men incorrectly classified as high risk was similar between tests. The researchers note that longer-term follow-up is needed to determine effects on mortality and long-term outcomes.

“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,” said Thorgerdur Palsdottir, a researcher at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.

"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," said Palsdottir.

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