High-intensity focused ultrasound uses ultrasound waves, emitted from a transducer, in order to damage tissue by cavitation and mechanical and thermal effects. To administer HIFU, a probe is inserted into the rectum (or urethra) while the patient is anaesthetised. This probe enables real-time visualization of prostatic tissue and also delivers HIFU energy to destroy the desired target parenchyma.
Two major systems of HIFU exist based on the type of imaging guidance during the treatment.
- HIFU with transrectal ultrasonography (TRUS) imaging guidance is the traditional approach and has been in use in Europe for many years. Its major limitation is that it is not possible to use current ultrasound systems to visualize the focus of cancer. Therefore, the treatment strategy with TRUS-guided HIFU is to ablate either the whole prostate gland or a relatively large region of it.
- The novel approach is the HIFU system with magnetic resonance imaging (MRI) guidance. MRI provides high-resolution imaging for patient-specific treatment planning and real-time thermometry for temperature monitoring during treatment. It is possible to localize the lesions within the prostate with MRI and, thus, to optimize the ablation zone. Therefore, focal treatment (FT) of the prostate is also.
The main advantages of HIFU treatment are claimed to be the lack of induction of apoptosis, thus avoiding late complications of treatment and the lack of a cumulative effect with the possibility of repeating procedure. It is also claimed that HIFU treatment has a significantly lower adverse effect profile (erectile and urinary dysfunction), and reduces toxicity compared with other ablation techniques; in addition, adjacent blood vessels might be less vulnerable compared with surgical risks.
HIFU has been compared with other treatment strategies, such as active surveillance, waitful watching, radical prostatectomy and radiation therapy.
The systematic review by LBI-HTA of 2010 was updated; thus new publications released 2010-2017 were taken into consideration. The Cochrane Library, Centre for Research and Dissemination (CRD), Embase, Medline were searched, together with manual searches in the reference lists of relevant studies, platforms with information on on-going studies (ClincalTrials.gov, EU Clinical Trials Register and International Clinical Trials Registry Platform (ICTRP)) and clinical practice guidelines from UptoDate. GRADE method was used in assessing the quality of the of evidence.
Conclusion
There is not enough evidence to determine whether primary HIFU is more or as equally as effective and/or has a better (or at least similar) safety profile compared with active surveillance, waitful watching and radical prostatectomy or radiation therapy for the treatment of prostate cancer.
There is insufficient evidence to determine whether salvage HIFU is more is more or as equally as effective and/or has a better (or at least similar) safety profile than active surveillance, waitful watching, salvage radical prostatectomy and salvage radiation therapy (s-RT) for the treatment of prostate cancer.
Therefore, a need for prospective RCTs with a higher number of patients and longer follow-up exists, in order to be able to determine whether HIFU is a suitable alternative to deferred treatment and/or standard radical therapies for the treatment of prostate cancer.
See the full report in English here.
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