Confirmatory Biopsy Outcomes in Patients with Grade Group 2 Prostate Cancer: Implications for Early Management

Background and objective: Guideline recommendations regarding early management of grade group (GG) 2 prostate cancer with confirmatory biopsy (cBx) are not well established. Our aim was to determine which patients with GG 2 cancer should undergo cBx before treatment decision-making by evaluating the probability of downgrading to GG 1 or no cancer on cBx. Methods: This was a single-institution retrospective analysis of patients with GG 2 prostate cancer who underwent cBx. We modeled the probability of having no Gleason pattern 4 on cBx according to magnetic resonance imaging (MRI) Prostate Imaging-Reporting and Data System (PI-RADS) score, presence of extraprostatic extension (EPE) on MRI, total length of pattern 4 across all cores on initial Bx, and prostate-specific antigen (PSA) density. Key findings and limitations: Among 301 patients, 62 (21%) were downgraded to GG 1 and 23 (8%) had no cancer on cBx. For patients with nonsuspicious MRI findings (PI-RADS 1–3; n = 123), the probability of having no pattern 4 on CBx was 34%, 20%, and 11% for 1, 2, and 3 mm of pattern 4 at initial Bx. For PI-RADS 4–5 without EPE on MRI (n = 146), the corresponding probabilities were 18%, 10%, and 5%. Patients with EPE on MRI (n = 32) had low probability (