Single application of high-intensity focused ultrasound as primary therapy of localized prostate cancer: Treatment-related predictors of biochemical outcomes

Objective Recent reports on high-intensity focused ultrasound (HIFU) treatment of localized prostate cancer suggest that preoperative risk groups of tumor recurrence are strong predictors of oncological outcomes. The purpose of this study is to determine the prognostic significance of treatment-related factors in relation to patient characteristics for biochemical outcomes after HIFU. Methods This retrospective single-center study included patients treated from December 2002 to December 2010 for localized prostate cancer with two generations of Ablatherm® HIFU devices (A1 and A2). All the patients underwent single HIFU treatment session under the concept of whole-gland therapy. Prostate surgery was performed before HIFU to downsize enlarged glands. Androgen deprivation therapy (ADT) was discontinued before HIFU. Biochemical failure (BCF) was defined as prostate specific antigen (PSA) nadir + 1.2 ng/mL (Stuttgart definition). Predictors of BCF were determined using Cox regression models. As covariates, patient-related factors (age, tumor characteristics, ADT) were compared with treatment-related factors (prostate volume, HIFU device generation, conduct of therapy, prostate edema, patient movement, anesthetic modalities). Results Three hundred and twenty-three (98.8%) out of 327 consecutive patients were evaluable for BCF. Median (interquartile range) follow-up was 51.2 (36.6-80.4) months. The overall BCF-rate was 23.8%. In multivariate analyses, higher initial PSA-values (Hazard ratio [HR]: 1.03; p < 0.001) and higher D'Amico risk stages (HR: 3.45; p < 0.001) were patient-related predictors of BCF. Regarding treatment-related factors, the A2 HIFU device was associated with a decreased risk of BCF (HR: 0.51; p = 0.007), while prostate edema had an adverse effect (HR: 1.8; p = 0.027). Short follow-up and retrospective study design are the primary limitations. Conclusion Success in a single HIFU session depends not merely on tumor characteristics, but also on treatment-related factors. Ablation is more efficacious with the technically advanced A2 HIFU device. Heat-induced prostate edema might adversely affect the outcome.