Micro-ultrasound for Confirmatory Reclassification Biopsy in Active Surveillance of Low-Risk Prostate Cancer

Active surveillance (AS) is the preferred management strategy for low-risk prostate cancer (PCa), though it poses challenges in monitoring patients. This study evaluates the impact and diagnostic accuracy of micro-ultrasound (mUS) in AS patients undergoing surveillance biopsies. Between October 2017 and August 2023, 215 patients with ISUP 1 PCa were prospectively enrolled and underwent mUS-guided surveillance biopsies using the ExactVu microUS system. The PRIMUS protocol was applied to detect suspicious lesions (PRIMUS score ≥3). Targeted biopsies were performed on identified mUS lesions and any MRI lesions, complemented by systematic biopsies. Results showed that 146 patients (67.9%) had suspicious lesions identified via mUS, with 1, 2, and 3 lesions noted in 109 (74.6%), 29 (19.8%), and 8 (5.4%) patients, respectively. The lesions were classified as PRI-MUS 3, 4, and 5 in 29 (19.8%), 97 (66.4%), and 20 (13.7%) patients. Among 167 patients with MRI, 140 (83.8%) had PI-RADS ≥3 lesions targeted. Histopathological analysis confirmed 65 patients (30.2%) with ISUP 1 PCa, while 75 patients (34.8%) were upgraded to ISUP ≥2 PCa. mUS exhibited sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 89.3%, 43.5%, 45.8%, and 88.4%, respectively, for detecting clinically significant PCa (csPCa). Notably, an AS microUS protocol could have spared biopsies in 69 patients (32.1%) without PRI-MUS ≥3 lesions, although it would have missed eight upgraded cases (11.5%). In conclusion, mUS is a valuable imaging tool for real-time targeting of suspicious lesions in AS protocols, demonstrating high sensitivity and NPV in detecting csPCa.