External Validation of the Cancer of the Prostate Risk Assessment Score to Predict Treatment Failure After High-Intensity Focused Ultrasound

Authors: 

Éder Silveira Brazão Jr., Victor Espinheira Santos, Thiago Camelo Mourão, Daniel Coser Gomes, Jayme Quirino Caon Nobre, Gustavo de Pádua Brazão, Renato Almeida Rosa de Oliveira, Cássia da Silva, Walter Henriques da Costa, Gustavo Cardoso Guimarães, Stênio de Cássio Zequi

Abstract

Background: High-intensity focused ultrasound (HIFU) is an emerging treatment for localized prostate cancer, but prognostic tools validated in this setting are lacking. This study aimed to determine whether the Cancer of the Prostate Risk Assessment (CAPRA) score predicts biochemical recurrence (BR) and treatment failure (TF) after whole-gland HIFU.

Materials and methods: retrospective cohort of 208 patients treated with HIFU at a Brazilian tertiary center between 2011 and 2019 was selected for this study. Patients were stratified using the CAPRA score (range: 0-10; low: 0-2, intermediate: 3-5, and high: 6-10). BR was defined by the Phoenix criterion. TF included salvage treatment, metastasis, systemic therapy, or prostate cancer-specific death. Kaplan-Meier, Cox regression, and time-dependent receiver operating characteristic curve analyses assessed prognostic performance. Calibration was evaluated with bootstrapped Cox models at 5 years.

Results: At a median follow-up of 47 months, the CAPRA score predicted BR (hazard ratio: 1.36, 95% confidence interval: 1.20-1.55) and TF (hazard ratio: 1.49, 95% confidence interval: 1.29-1.72). Five-year BR-free survival was 81.5%, 50.7%, and 16.4% for low-, intermediate-, and high-risk groups, respectively. Areas under the curve for BR and TF at 60 months were 0.747 and 0.783, respectively. The CAPRA score stratified risk within D’Amico groups. Calibration was good for both outcomes. Limitations include retrospective design, single-center data, and the absence of systematic post-HIFU biopsy.

Conclusions: The CAPRA score is a valid predictor of oncological outcomes after HIFU and provides additional risk stratification beyond traditional systems. Its simplicity and accuracy support its integration into clinical decision-making for patients undergoing prostate ablation. Prospective multicenter studies are needed for broader validation.