Extracorporeal high intensity focused ultrasound in the treatment of patients with solid malignancy

The ideal treatment of localized cancer should cause the complete death of tumor cells without damage to surrounding normal tissue. High intensity focused ultrasound (HIFU) is such a potential treatment, which can induce complete coagulation necrosis of a targeted tumor, at depth, through the intact skin. The concept of using HIFU as a non-invasive therapy has attracted attention in medicine for 60 years. Recently, it has received increasing interest as a promising modality for the treatment of localized solid malignancies. The goal of this article is to introduce recent clinical developments in the use of extracorporeal HIFU ablation for solid tumors, including those of liver, breast, bone, kidney, pancreas, soft tissue, and uterus. It describes the physical principles and ablative mechanisms, three-dimensional therapeutic regimes, and medical imaging used in HIFU. Currently, large numbers of patients with solid malignancy are already treated using HIFU, and short-term clinical results are very encouraging. However, large-scale randomized clinical trials are necessary to evaluate long-term efficacy of HIFU treatment for solid malignancies. It is concluded that this non-invasive ablation can be considered as a conventional therapy for widespread clinical use only when the results from prospective, randomized clinical trials worldwide are available.