Focal Therapy for Localized Prostate Cancer with Either High Intensity Focused Ultrasound or Cryoablation: A Single Institution Experience

Abstract

Purpose: We report oncologic outcomes in patients treated with focal therapy for prostate cancer.

Materials and methods: We retrospectively analyzed a single institution cohort of men with localized prostate cancer who received focal therapy using high intensity focused ultrasound or cryotherapy from 2009 to 2018. Focal therapy was offered for low or intermediate risk disease (prostate specific antigen less than 20 ng/ml, Gleason score 7 or less and clinical stage T2b or less). Patients with previous prostate cancer treatment or less than 6 months of followup were excluded from study. Failure was defined as local or systemic salvage treatment, a positive biopsy Gleason score of 7 or greater in-field or out-of-field in nontreated patients, prostate cancer metastasis or prostate cancer specific death. Cox regression analysis was done to identify independent predictors of failure after focal therapy.

Results: Of the 309 patients included in study 190 and 119 were treated with high intensity focused ultrasound and cryotherapy, respectively. Median followup was 45 months. At 1, 3 and 5 years the failure-free survival rate was 95%, 67% and 54%, and the radical treatment-free survival rate was 99%, 79% and 67%, respectively. The 5-year metastasis-free survival rate was 98% and no prostate cancer specific death was registered in this cohort. Before focal therapy a biopsy Gleason score of 7 (3 + 4) or greater (HR 2.4, p <0.001) and nadir prostate specific antigen (HR 2.2, p <0.001) were independently associated with failed focal therapy. In the salvage focal therapy setting in-field recurrence after primary focal therapy was associated with poorer failure-free survival (p=0.02).

Conclusions: Almost half of the men were free of focal therapy failure 5 years after treatment. Still, a significant proportion experienced recurrence at the midterm followup. The preoperative biopsy Gleason score and nadir prostate specific antigen were significantly associated with treatment failure.

Keywords: biopsy; cryotherapy; high-intensity focused; prostatic neoplasms; transrectal; treatment failure; ultrasound.