Adding a blood-based biomarker test to prostate screening with MRI can improve cancer detection, according to research published June 22 in the Annals of Internal Medicine.
Stockholm3, a test that combines data from multiple areas, showed greater clinical net benefit than PSA for detecting clinically significant prostate cancer in a patient population that underwent MRI screening.
“These findings support the use of Stockholm3 in the context of a risk-adapted screening approach, enabling more precise identification of men at higher risk for clinically significant disease while reducing unnecessary biopsies,” wrote a team led by Thorgerdur Palsdottir, PhD, from the Karolinska Institute in Stockholm, Sweden.
Stockholm3 is a blood test that combines data from PSA, plasma protein biomarkers, polygenic risk, and clinical factors to create a risk score for prostate cancer.
In its application in the STHLM3-MRI trial, Stockholm3 estimated the risk of detecting clinically significant prostate cancer. The trial uses PSA, Stockholm3, and MRI data for prostate cancer screening. During primary analysis, the trial showed that MRI followed by biopsy is noninferior to systematic biopsy for detecting clinically significant prostate cancer. The blood test initially measures PSA, and for a PSA level of 1.5 ng/mL or greater, the other components of Stockholm3 are performed.
The researchers previously found that this approach finds cancers missed by conventional PSA thresholds while reducing unnecessary biopsies in men with high testing values at screening. For their current study, Palsdottir and colleagues compared PSA and Stockholm3 in the baseline round of the population-based STHLM3-MRI trial and identified clinically significant cancers diagnosed within two years of the screening blood test.
The study included 12,670 men, of whom 443 were diagnosed with clinically significant prostate cancer. Men with abnormal screening tests were randomly assigned in a 2:3 ratio to either systematic biopsy or MRI with systematic and targeted biopsies for PI-RADS 3 or greater lesions.
Decision curve analysis showed higher net benefit for Stockholm3 versus PSA across a range of decision thresholds for biopsy. This meant fewer unnecessary biopsies and fewer missed clinically significant cancers for Stockholm3.
Stockholm3 also had a lower false-negative rate and higher sensitivity than PSA.
Comparison between Stockholm3, PSA testing for prostate cancer detection | ||
Measure | PSA | Stockholm3 |
False-negative rate | 26% | 10% |
False-positive rate | 10% | 11% |
Sensitivity | 74% | 90% |
Specificity | 90% | 89% |
The study authors called for future studies to focus on longer-term follow-up of survival and cause-specific mortality, as well as evaluate the long-term effect and cost-effectiveness of this screening approach.
“If confirmed, integrating Stockholm3 into screening pathways may improve the efficiency and clinical utility of prostate cancer screening programs,” they wrote.
Read the full study here.
