New and Established Technology in Focal Ablation of the Prostate: A Systematic Review

Abstract

Context: Focal therapy of prostate cancer has been proposed as an alternative to whole-gland treatments.

Objective: To summarize the evidence regarding sources of energy employed in focal therapy.

Evidence acquisition: Embase and Medline (PubMed) were searched from 1996 to October 31, 2015 following the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. Ongoing trials were selected from electronic registries. The stage of assessment of each source of energy was determined using the Idea, Development, Exploration, Assessment, Long-term study recommendations.

Evidence synthesis: Thirty-seven articles reporting on 3230 patients undergoing focal therapy were selected. Thirteen reported on high-intensity focused ultrasound, 11 on cryotherapy, three on photodynamic therapy, four on laser interstitial thermotherapy, two on brachytherapy, three on irreversible electroporation, and one on radiofrequency. High-intensity focused ultrasound, cryotherapy, photodynamic therapy, and brachytherapy have been assessed in up to Stage 2b studies. Laser interstitial thermotherapy and irreversible electroporation have been evaluated in up to Stage 2a studies. Radiofrequency has been evaluated in one Stage 1 study. Median follow-up varied between 4 mo and 61 mo, and the median rate of serious adverse events ranged between 0% and 10.6%. Pad-free leak-free continence and potency were obtained in 83.3-100% and 81.5-100%, respectively. In series with intention to treat, the median rate of significant and insignificant disease at control biopsy varied between 0% and 13.4% and 5.1% and 45.9%, respectively. The main limitations were the length of follow-up, the absence of a comparator arm, and study heterogeneity.

Conclusions: Focal therapy has been evaluated using seven sources of energy in single-arm retrospective and prospective development studies up to Stage 2b. Focal therapy seems to have a minor impact on quality of life and genito-urinary function. Oncological effectiveness is yet to be defined against standard of care.

Patient summary: Seven sources of energy have been employed to selectively ablate discrete areas of prostate cancer. There is high evidence that focal therapy is safe and has low detrimental impact on continence and potency. The oncological outcome has yet to be evaluated against standard of care.

Keywords: Focal therapy; Partial ablation; Prostate cancer.