Salvage external beam radiotherapy for recurrent prostate adenocarcinoma after high-intensity focused ultrasound as primary treatment.

INTRODUCTION

The main objective was to evaluate feasibility, toxicity and biochemical control rates of salvage external beam radiotherapy (EBRT) in recurrent localized prostate cancer after high-intensity focused ultrasound (HIFU) as primary therapy.

PATIENTS AND METHODS

A total of 24 patients who underwent salvage EBRT after 1 or 2 HIFU sessions and with a minimum post-treatment follow-up of 24 months were retrospectively evaluated. Primary endpoints were toxicity and biochemical disease-free survival (bDFS, defined according to the ASTRO Phoenix definition).

RESULTS

Median follow-up was 40.3 months. Gastrointestinal toxicity was low. Acute genitourinary (GU) toxicity grade ≤II rate was 45.8%, with only few patients presenting grade III (8.3%) and grade IV (4.2%) toxicity. Late grade ≥III GU toxicity was registered in 16.7% of patients. The 3-year bDFS rate was 77.8%. Patients achieving a nadir prostate-specific antigen (nPSA) of ≤0.35 ng/ml after EBRT had significantly higher bDFS (3-year bDFS: 87.7 vs. 50%, respectively; p = 0.001). Achieving nPSA ≤0.35 ng/ml was the only factor independently associated to long-term bDFS both on univariate (p = 0.01) and multivariate analysis (HR 7.06, p = 0.039).

CONCLUSIONS

Salvage EBRT after HIFU failure is feasible and allows to obtain satisfactory biochemical control rates, especially in patients attaining a nPSA ≤0.35 ng/ml after EBRT.