Incremental Value of Systematic Biopsy in Patients with Prostate Imaging Reporting and Data System 5 Lesions Undergoing MRI–Ultrasound Fusion Biopsy: A Single-Operator Study in a Secondary-Care Setting

Background/Objectives: This study aimed to evaluate the incremental value of systematic biopsy (SB) in addition to targeted biopsy (TB) and its impact on Grade Group (GG) reclassification in patients with Prostate Imaging Reporting and Data System (PI-RADS) 5 lesions. Methods: We retrospectively reviewed data from 32 patients with PI-RADS 5-only lesions who underwent magnetic resonance imaging–ultrasound fusion transrectal biopsy by a single operator. Based on the patient-level maximum GG, we evaluated the detection of any prostate cancer (GG ≥ 1), clinically significant prostate cancer (GG ≥ 2), and high-grade prostate cancer (GG ≥ 3). An exploratory subgroup analysis was performed according to prostate-specific antigen density (PSAD; <0.15 vs. ≥0.15 ng/mL/mL). Results: Any prostate cancer was detected in 24 patients (75.0%) using TB, with no incremental detection using SB (0.0%; 95% confidence interval [CI], 0.0–10.9). Clinically significant prostate cancer was detected in 21 patients (65.6%) using TB, with incremental detection using SB in one patient (3.1%; 95% CI, 0.1–16.2). High-grade prostate cancer was detected in 17 patients (53.1%) using TB, with incremental detection using SB in one patient (3.1%; 95% CI, 0.1–16.2). The maximum GG was higher in three patients (9.4%) when TB and SB were combined. Among the 20 patients with PSAD ≥ 0.15 ng/mL/mL, no incremental detection of clinically significant prostate cancer or high-grade prostate cancer was observed using SB (0.0%; 95% CI, 0.0–16.8). Conclusions: In this cohort of patients with PI-RADS 5 lesions, the incremental value of SB for cancer detection was limited, although the upper limit of the 95% CI for incremental detection of clinically significant prostate cancer was 16.2%. Nevertheless, SB provided additional grading information in a small number of patients. Larger studies are needed to evaluate the clinical value of selective SB omission in patients with PI-RADS 5 lesions.