How a New Prostate Cancer Test Beats PSA in Screening

Prostate cancer screening remains a controversial topic in modern medicine. Traditional prostate-specific antigen (PSA) testing often leads to overdiagnosis and unnecessary biopsies. Therefore, researchers evaluated the Stockholm3 screening test as a highly promising alternative. This advanced tool combines plasma protein biomarkers, polygenic risk, clinical factors, and PSA to calculate a comprehensive score. Additionally, a secondary analysis of the STHLM3-MRI trial recently compared this approach against traditional PSA screening.

Clinical Evaluation of the Stockholm3 Screening Test

Researchers analyzed data from 12,670 men aged 50 to 74 years in Sweden between 2018 and 2020. Specifically, participants underwent both PSA testing and the Stockholm3 test at baseline. The team defined abnormal results as a PSA of 3 ng/mL or greater, or a Stockholm3 score of 11 or greater. Consequently, men with abnormal results underwent a random assignment to either systematic biopsy or magnetic resonance imaging (MRI). If the MRI showed a lesion, the team performed systematic and targeted biopsies. Finally, researchers tracked prostate cancer diagnoses for two years using the Swedish National Cancer Register to identify missed cases.

Superior Sensitivity and Higher Net Benefit

During the two-year follow-up, doctors diagnosed 443 men with clinically significant prostate cancer. Overall, decision curve analysis showed a significantly higher net benefit for the Stockholm3 pathway compared to standard PSA testing. This advantage translates directly to fewer unnecessary biopsies and fewer missed cases of aggressive cancer. For example, the Stockholm3 test demonstrated a sensitivity of 90%, whereas the PSA test achieved only 74% sensitivity. Correspondingly, the two methods maintained similar specificity at 89% and 90%, respectively. Furthermore, the Stockholm3 test missed significantly fewer cancers than standard PSA testing.

Reducing False-Negative Results in Screening

The study highlighted a major reduction in false-negative outcomes with the multicomponent test. Specifically, the Stockholm3 test produced a false-negative rate of only 10%, compared to 26% for the standard PSA test. However, the false-positive rates remained very comparable between the two cohorts. Moreover, Stockholm3 showed an 11% false-positive rate, while PSA showed a 10% rate. Therefore, the multicomponent test detects more aggressive cancers without substantially increasing the number of false alarms. These results support a risk-adapted screening approach to enhance patient outcomes.

Study Limitations and Clinical Implications

The researchers noted several key limitations in their secondary analysis. First, only 25% of the invited men chose to participate in the screening program. Consequently, this self-selection may introduce participation bias. Second, the study follow-up lasted only two years, which limits long-term mortality data. Finally, the predominantly European cohort may restrict the generalizability of these findings to diverse populations like India. Nevertheless, the study shows that this risk-prediction model could significantly refine prostate screening strategies.

Frequently Asked Questions

Q1: What is the main difference between the Stockholm3 screening test and standard PSA testing?

The Stockholm3 screening test is a multivariable risk-prediction model. Specifically, it combines PSA with plasma protein biomarkers, clinical factors, and genetic risk scores. In contrast, standard PSA testing relies solely on a single blood protein level.

Q2: How does the sensitivity of the Stockholm3 screening test compare to traditional PSA?

The Stockholm3 screening test demonstrated a sensitivity of 90% in detecting clinically significant prostate cancer. Conversely, the standard PSA test achieved a sensitivity of only 74% in the same cohort.

Q3: Does the Stockholm3 test increase the number of false-positive results?

No, because the Stockholm3 test maintains a highly comparable specificity to PSA testing. Specifically, the trial reported false-positive rates of 11% for Stockholm3 and 10% for PSA. Therefore, it detects more aggressive cancers without increasing unnecessary biopsies.

References

1. Palsdottir T et al. Stockholm3-Magnetic Resonance Imaging Population-Based Prostate Cancer Screening Study: Two-Year Follow-up. Ann Intern Med. 2026 Jun 23. doi: 10.7326/ANNALS-25-04753. PMID: 42330502.
2. Nordström T, et al. Prostate cancer screening using a combination of risk-prediction, MRI, and targeted prostate biopsies (STHLM3-MRI): a prospective, population-based, randomised, open-label, non-inferiority trial. Lancet Oncol. 2021 Sep;22(9):1240-1249. doi: 10.1016/S1470-2045(21)00348-X.