A new blood test may make it easier to detect the most dangerous forms of prostate cancer early on. In a study from Karolinska Institutet, the Stockholm3 blood test detected more clinically significant cancer cases than the PSA test, without subjecting more men to unnecessary testing. The study was published in the Annals of Internal Medicine.
In a large population-based study involving 12,670 men aged 50-74, researchers at Karolinska Institutet show that the blood-based Stockholm3 test identifies significantly more aggressive prostate cancers than traditional PSA testing. Stockholm3 detected 90 percent of aggressive cancer cases, compared to 74 percent for PSA.
Need for better methods
Prostate cancer is one of the most common forms of cancer among men globally. PSA testing has long been used for early detection, but is controversial because it can both miss aggressive tumors and lead to unnecessary further investigations and biopsies.
The new results suggest that Stockholm3 may offer a more accurate alternative.
"The major challenge in prostate cancer screening is not just to find more cancer cases, but to identify the cancers that are truly dangerous," says Thorgerdur Palsdottir , a researcher at the Department of Medical Epidemiology and Biostatistics , Karolinska Institutet.
"Our results show that Stockholm3 identifies significantly more aggressive cancer cases than PSA, without increasing the number of unnecessary follow-ups."
The study is based on the population-based STHLM3-MRI study. All participants were tested with both PSA and Stockholm3 and followed for two years via national cancer registries, which made it possible to also identify cancer cases that were missed during the initial screening.
Missed fewer serious cases
During the follow-up, 443 men were diagnosed with clinically significant, i.e., aggressive, prostate cancer. Stockholm3 missed significantly fewer serious cancer cases than PSA, while the proportion of men incorrectly classified as high-risk was similar between the tests.
"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," says Thorgerdur Palsdottir.
The researchers emphasize that longer-term follow-up is needed to fully assess the effects on mortality and long-term outcomes.
The study was conducted in collaboration with researchers and clinicians in Sweden, Europe, and the United States. The research was funded by the Swedish Research Council, Region Stockholm, the Prostate Cancer Association, and the Cancer Foundation. The researchers state that the funders played no role in the study design or interpretation of the results and that there are no conflicts of interest.
Publication
"Stockholm3-Magnetic Resonance Imaging Population-Based Prostate Cancer Screening Study: Two-Year Follow-Up" , Thorgerdur Palsdottir, Chiara Micoli, Martin Eklund, Henrik Grönberg, Fredrik Jäderling, Derya Tilki, Daniel Lin, Matthew Cooperberg, Scott Eggener, Kevin C. Oeffinger, Tobias Nordström, Hari Vigneswaran, Annals of Internal Medicine, online 22 June 2026, doi: 10.7326/ANNALS-25-04753.
