Active Surveillance for Prostate Cancer

The CHAS3 trial studies whether the Stockholm3 blood test can reliably detect if prostate cancer becomes more aggressive in men who are being carefully monitored instead of treated right away (active surveillance). The goal is to see if this test can help doctors safely follow patients with fewer invasive procedures, such as repeated biopsies.

Active surveillance is a common approach for men with low-risk or favorable intermediate-risk prostate cancer, aimed at avoiding or delaying treatment while closely monitoring the disease. Multiparametric MRI (mpMRI) is widely used to guide diagnosis and follow-up, but it can miss clinically significant prostate cancer and may be limited by access, cost, and variability in interpretation. Micro-ultrasound is a high-resolution ultrasound technique that may improve real-time detection of suspicious prostate lesions using a standardized scoring system (PRI-MUS). The purpose of this study is to evaluate the diagnostic performance of micro-ultrasound for detecting clinically significant prostate cancer in men with negative or stable mpMRI findings, either at initial diagnosis or during active surveillance follow-up. Participants will undergo micro-ultrasound assessment of the prostate. Areas considered suspicious on micro-ultrasound may be targeted for biopsy, followed by systematic prostate sampling. Biopsy results will be used as the reference standard to determine whether clinically significant prostate cancer is present. The study will assess measures such as sensitivity, specificity, and predictive values of micro-ultrasound, as well as procedure-related complications.