**7. HIFU Therapy for prostate cancer: Its role in focal therapy**

HIFU for the treatment of localized prostate cancer was developed in 1990. Nowadays there are two available devices for the treatment of prostate cancer: the Ablatherm™ (EDAP TMS S.A., Vaulx-en-Velin, France) and the Sonablate™ (Focus Surgery, Inc, Indianapolis, Indiana, USA) [26].

Both of them have a simultaneous imaging technique coupled to the treatment device. They differ by patient positioning and the degree of manual control of power. Currently, the technique is used among many cancer centers despite the fact that available guidelines do not recommend it for the treatment of localized prostate cancer. In 2010, the Cancer Care Ontario group excluded HIFU from its recommendations due to lack of randomized controlled clinical trials and short follow up [27]. The NICE guidelines in 2012 considered HIFU as an experi‐ mental technique with further studies needed in order to conclude [28]. In 2014, the FDA bans the use of HIFU for whole-gland primary treatment of clinically localized prostate cancer. At present, high quality evidence on efficacy and safety of HIFU is based on uncontrolled case series with a significant overlap of patients among series. There are no direct comparisons with active surveillance or whole gland radical therapies. Furthermore, the technique is not standardized and patient selection is not unanimous. The ideal candidate is defined as a patient aged > 70 years of age, with clinical stage T1-T2 N0M0, a Gleason score<7, a PSA level <15 ng/ ml and a prostate volume of <40 ml, in particular if the patient is unsuitable for or refuse radical therapy [26]. A prostate volume of >40 ml and the presence of large calcifications are a contraindications for HIFU. In such cases where the volume exceed 40 ml a TURP or a cytoreductive androgen deprivation therapy or a 5 alpha reductase inhibitor before HIFU is recommended to reduce the volume of the prostate. The number of HIFU treatment per patient varies between one and five. The median follow up time is short with the longest series reporting data after a median follow up of 94 months [29].

HIFU could be used as a primary treatment or as a salvage therapy in recurrent prostate cancer after radiotherapy failure. The field could involve a whole gland ablation or a more focal therapy. For technical considerations, Hemiablation HIFU of an entire lobe delivered with intention to treat is currently used for focal therapy. The technique was demonstrated to be feasible and functional and disease control outcomes were encouraging at 3 years of follow up.
