Energy-based ablative therapy of prostate cancer: high-intensity focused ultrasound and cryoablation

This review is an update on the role of the two minimally invasive techniques in primary therapy of organ-confined prostate cancer: as a salvage option after standard-therapy failure and for focal ablation of index tumors.

Energy-based ablative techniques are of growing interest for today's heterogeneous spectrum of prostate cancer. At present, primary high-intensity focused ultrasound appears to be a valid alternative to active surveillance protocols in low-risk cancers and, in older patients, to standard therapy. Morbidity is low, although postoperative impotence occurs frequently. Cryoablation has higher morbidity, even with third-generation conformal technology. With radiorecurrent cancer the potential radiation damage of the rectal wall renders transrectal high-intensity focused ultrasound more hazardous. Third-generation cryoablation seems to give better cancer control with lower morbidity in this situation. Unfortunately, long-term outcome data from controlled trials are not available.

These minimally invasive techniques are not magic bullets, and patients must be informed accordingly. Focal ablation of the prostate segment with the index cancer would minimize morbidity and therefore appears highly appealing. Its success depends on correct localization of the lesion. Until this is achieved with sufficient reliability by appropriate biopsy or imaging techniques it remains strictly experimental.