Salvage radiotherapy after high-intensity focused ultrasound treatment for localized prostate cancer: feasibility, tolerance and efficacy

Abstract

Background: The objective of this study is to evaluate the feasibility,tolerance and efficacy of salvage external beam radiotherapy(EBRT) in persistent or recurrent prostate cancer after failed highintensity focused ultrasound (HIFU) therapy.Methods: We reviewed data on tolerance and oncologic outcomesfor all patients with biopsy-proven locally recurrent or persistentprostate cancer who underwent salvage EBRT in our departmentbetween April 2004 and June 2008. Minimum follow-up for inclusionwas 2 years. Failure with EBRT was defined as biochemicalrelapse (Phoenix definition) or introduction of androgen deprivationtherapy (ADT). Gastrointestinal and urinary toxicity and urinary stressincontinence were scored at 12 and 24 months (Radiation TherapyOncology Group and Ingelman Sundberg rating, respectively).Results: The mean age of the patients was 68.8 years (range: 60-79).Mean prostate-specific antigen (PSA) before EBRT was 5.57 ng/mL(range: 2.5-14.8). Median follow-up was 36.5 ± 10.9 months(range: 24-54). No patient received adjunctive ADT. The EBRTcourse was well-tolerated and completed by all patients. The meanPSA nadir was 0.62 ng/mL (range: 0.03-2.4) and occurred after amedian of 22 months (range: 12-36). One patient experiencedbiochemical failure and was prescribed ADT 30 months after EBRT.The disease-free survival rate was 83.3% at 36.5 months. Therewas no major EBRT-related toxicity at 12 or 24 months.Conclusions: Our early clinical results confirm the feasibilityand good tolerance of salvage radiotherapy after HIFU failure.Oncological outcomes were promising. A prospective study withlonger follow-up is needed to identify factors predictive of successfor salvage EBRT therapy after HIFU failure.