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Baseline Gleason Pattern 4 Length Associated with Recurrence after Primary Focal Ablation for Grade Group 2 Prostate Cancer Cohort
Anthony Zhang, BS, Christopher Hayden, MD, Nethusan Sivanesan, BS, Andrea Lopez-Sanmiguel, MD, Preston C. Sprenkle, MD.
Yale University School of Medicine, New Haven, CT, USA.
Introduction: Grade group (GG) 2 prostate cancer (PCa) represents a heterogeneous risk category, highlighting the need for improved risk stratification beyond Gleason grade. Quantitative assessment of Gleason pattern 4 (GP4) burden may refine patient selection for focal therapy (FT). We evaluated whether baseline GP4 length predicts recurrence following FT and characterized post-treatment GP4 changes.
Methods: We retrospectively reviewed men with GG2 PCa treated with primary FT (cryoablation/transurethral ultrasound ablation/irreversible electroporation). FT was defined as ≤50% prostate ablation. All patients underwent 12-month post-FT biopsy. The primary endpoint was clinically significant PCa recurrence (GG≥2). Baseline GP4 length was defined as the maximal GP4 core length on biopsy. Statistical tests included Wilcoxon rank-sum and Fisher's exact.
Results: Among 72 patients, 17 (23.6%) developed recurrence, of whom 12 (70.6%) remained GG2 and 5 (29.4%) upgraded. Median follow-up was 30.7 months. Baseline age, PSA, prostate volume, and PSAD did not differ by recurrence. Median baseline GP4 length was significantly greater in patients who recurred (1.20 mm vs 0.50 mm, p=0.0036). Recurrence rates did not differ by FT modality. At 12 months, 60/72 (83.3%) demonstrated no residual GP4. Across all patients, 68/72 (94.4%) had decreased or absent GP4 burden following FT. Among recurring patients, 8 (66.7%) demonstrated reduced GP4 length despite persistent disease. Residual GP4 in 12 (17.4%) patients had a median length of 0.48mm, comparable between in-field and out-field recurrences (p≥0.77).
Conclusions: Within this cohort, baseline GP4 length was associated with recurrence following FT in GG2 PCa, supporting its role as a prognostic marker for patient selection. Despite this, most patients demonstrated marked reduction or elimination of GP4 following treatment, suggesting effective ablation of clinically significant disease. Quantitative GP4 assessment may improve risk stratification and guide post-treatment surveillance.
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