Introduction:

Cancer of the Prostate Risk Assessment (CAPRA) score determines the overall risk of recurrence after patients with prostate cancer (PCa) undergo treatment. CAPRA ranges from 0 (lowest) to 10 (highest risk) and is computed from five clinical components: age, PSA, Gleason grade, percent of biopsy positive cores, and T-stage, each with distinct point-based thresholds. High-Intensity Focused Ultrasound (HIFU) is primarily 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 a one-year follow-up using CAPRA.

Methods:

Men with PCa who underwent a pre-HIFU biopsy, HIFU procedure, and a one-year post-HIFU biopsy were included in this analysis. Post-HIFU biopsies included both systematic sampling and targeted sampling of the treated lesion. Clinical CAPRA scores and component variables were reported 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. 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 were included in this analysis who completed a biopsy pre-HIFU and a one-year biopsy post-HIFU. Pre-HIFU CAPRA scores were 21% low-, 69% intermediate-, and 10% high-risk. Of the 142 men, 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+. Post-HIFU CAPRA score improved by 1 or more points for 78% of patients, stayed the same for 11%, and worsened for 11%. Risk category improved at 1 year for 56%. 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. Pre-HIFU 21% of patients were in the low-risk category, but post-HIFU this number increased to 70%; 69% of patients were in the intermediate-risk category pre-HIFU and this decreased to 25% of patients post-HIFU, p<0.01.

Conclusion:

After HIFU, three quarters of patients had reduced CAPRA scores by at least 1 point and half had a lower risk category. 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 and T-stage were not significantly associated.

Funding: UCSF Goldberg-Benioff Program in Translational Cancer Biology