New Blood Test Outperforms PSA at Catching Dangerous Prostate Cancers

Prostate cancer screening has long relied on the PSA blood test, which is imperfect — it misses cancers and triggers unnecessary biopsies. A new analysis suggests a more sophisticated blood-based test could meaningfully improve early detection of the cancers that actually matter.

The Stockholm3 test combines standard PSA with additional plasma protein biomarkers, a polygenic risk score reflecting genetic cancer risk, and clinical variables like age and family history. Researchers from the Karolinska Institutet conducted a secondary analysis of the STHLM3-MRI randomized trial, examining over 12,600 Swedish men screened between 2018 and 2020 with two-year follow-up.

The findings, published in the Annals of Internal Medicine, were striking. Stockholm3 detected 90% of clinically significant prostate cancers — defined as grade group 2 or higher — compared to 74% for PSA alone. Crucially, this improvement came without increasing false positives meaningfully: the false-positive rate was 11% for Stockholm3 versus 10% for PSA. Per 1,000 men screened, Stockholm3 identified 31.6 significant cancers versus 25.8 for PSA, while producing similar numbers of unnecessary diagnostic workups.

This matters because the harms of prostate cancer overdiagnosis are well-documented — unnecessary biopsies carry infection risk, anxiety, and can lead to overtreatment of slow-growing cancers that would never cause harm. Stockholm3 addresses both sides of this problem: catching more dangerous cancers while avoiding more false alarms.

The test is already used clinically in parts of Europe and has been validated in prior STHLM3-MRI trial phases. However, this was a secondary analysis rather than a primary trial endpoint, and generalizability to non-European populations requires further study. Men and clinicians interested in optimizing prostate cancer screening should discuss whether multicomponent testing is available and appropriate given individual risk profiles.