Focal therapy of prostate cancer: energies and procedures

Over the last years, focal therapy has emerged as an intermediate management technique between radical approaches (radical prostatectomy, external beam radiation, and brachytherapy) and watchful waiting to manage some early stage prostate cancers (CaP). Different energy modalities are being developed. The aim of this study is to review these energy modalities and their indications.

We reviewed the literature to concentrate on the practical aspects of focal therapy for CaP with the following key words: photodynamic therapy, high intensity focused ultrasound (HIFU), cryotherapy, focal laser ablation, electroporation, radio frequency, external beam radiation, organ-sparing approach, focal therapy, CaP, and then by cross-referencing from previously identified studies.

Prostatic tumor ablation can be achieved with different energies: freezing effect for cryotherapy, thermal effect using focalized ultrasound for HIFU, and using thermal effect of light for focal laser ablation (FLA) and activation of a photosensitizer by light for PDT, among others. Radio frequency and microwave therapy have been tested in this field and demonstrated their usefulness. Electroporation is currently being developed on preclinical models. External beam radiation with microboost on neoplastic foci is under evaluation. HIFU and cryotherapy require the use of sophisticated and expensive machines and, consequently, the procedure is expensive. Laser techniques seem to be less onerous, with the added advantage of size.

Several energy modalities are being developed to achieve the trifecta of continence, potency, and oncologic efficiency. Those techniques come with low morbidity but clinical experience is limited regarding to oncologic outcome. Comparison of the different focal approaches is complex owing to important heterogeneity of the trials. In the future, it seems likely that each technique will have its own selective indications.