Biopsy patterns following high intensity focused ultrasound as assessed by CAPRA score.

Abstract

324 Background: Cancer of the Prostate Risk Assessment (CAPRA) score determines the overall risk of recurrence after patients with prostate cancer (PCa) undergo treatment. CAPRA (range 0-10 (highest risk)) is computed from five clinical components: age, PSA, Gleason grade, percent biopsy positive cores, and T-stage, each with distinct point-based thresholds. High-Intensity Focused Ultrasound (HIFU) is used to treat patients with clinically significant (GG2 or higher) focal lesions in one lobe with or without GG1 on the contralateral side. Here we assess biopsy patterns at one-year follow-up using CAPRA. Methods: Men with PCa underwent a pre-HIFU biopsy, HIFU procedure, and a one-year post-HIFU biopsy. Pre- and post-HIFU biopsies included both systematic sampling and targeted sampling of the treated lesion. Clinical CAPRA scores were computed before and after HIFU. The primary outcome was change in CAPRA risk category [Low-Risk (0-2), Intermediate-Risk (3-5), High-Risk (6-10)] for those that had residual disease. The secondary outcome was improvement of post-HIFU CAPRA score by 1 or more points. Descriptive analyses of the CAPRA components associated with residual disease after HIFU were performed. Categorical variables were compared with the chi-square test. Results: 142 men had biopsies before and one year after HIFU. Pre-HIFU CAPRA scores were 21% low-, 69% intermediate-, and 10% high-risk; 40% had negative biopsies of the treated area, 20% had GG1, and 40% had GG2+. For out-of-field recurrence, 69% had negative biopsies, 20% had GG1, and 11% had GG2+. Prior to HIFU, 19% of men with low-, 32% with intermediate-, and 23% with high-risk CAPRA had a positive PIRADS and a high Decipher Genomic Classifier (GC) score. 54% of patients had ≤33% positive biopsy cores pre-HIFU, which increased to 84% post-HIFU, p<0.01. Post-treatment improvements in PSA and tumor volume, as assessed by percent of positive cores, were associated with improvements in CAPRA score, both p<0.01. Post-HIFU CAPRA score improved by 1 or more points for 78% of patients, stayed the same for 11%, and worsened for 11%. 20% with improved CAPRA score had benign or no cancer post-HIFU. Risk category improved at 1 year for 56%. Patients in the low-risk category increased from 21% pre-HIFU to 70% post-HIFU, p<0.01. Patients in the intermediate-risk category decreased from 69% pre-HIFU to 25% post-HIFU, p<0.01. Conclusions: After HIFU, half of patients had a lower CAPRA risk category, and three quarters of patients had reduced CAPRA scores by at least 1 point. While persistent (GG1) and recurrent (GG2+) disease appeared to be common after HIFU, as assessed by Gleason grade infield/outfield recurrence rates, HIFU treatment was associated with a clear decrease in cancer risk as assessed by CAPRA. Post-treatment reductions in PSA and tumor volume were associated with improvements in CAPRA score, while age, T-stage, PIRADS, and GC were not significantly associated.