High intensity focused ultrasound in the treatment of small kidney tumours— The Oxford experience

14645 Background: High-intensity focused ultrasound (HIFU) provides a potential non-invasive alternative to conventional therapies. We have been using the extracorporeal ultrasound-guided Model-JC Tumor Therapy System (HAIFU Technology Company, China) in clinical trials to evaluate the safety and feasibility of treating small renal tumours. Methods: Patients with renal tumours less than 4cm diameter and unsuitable for surgery were treated with HIFU were enrolled into this phase II prospective trial. Treatment was delivered under general anaesthesia in a single session using the Model-JC Tumor Therapy System. Magnetic resonance imaging (MRI) 12 days after treatment provided an initial assessment of response (technical success). Patients are followed-up with further MR imaging at 6 months and one year to gauge technique effectiveness. A total of 14 patients will be included in the trial. Results: Eight patients with kidney tumours have been treated to date. All eight have had pre- and 12-day post-treatment MR imaging. One patient was not included in the analysis as treatment was suspended due bowel interposition in the treatment field during therapy. MRI changes suggestive of kidney tumour response have been seen in 4/7 (57%) cases. Complete ablation has been seen in two cases and partial ablation in two cases. One patient remains disease free 12 months after HIFU. Mild transient discomfort was reported by 4/8 patients (50%), and moderate discomfort in 3/8 (38%) but more severe pain needing opiate analgesia has not been encountered in this series. Minor skin toxicity (1mm blister at the treatment site) was seen in two patients. All patients were discharged the day after the procedure. There have been no adverse effects on renal, haematological or hepatic function. Conclusions: Extracorporeal HIFU has the ability to completely ablate small renal tumours. Our early clinical experience suggests that HIFU treatment of kidney tumours is safe and extremely well tolerated. The reasons for the variability in observed response remain obscure, and reliability of tumour ablation will need to improve before extracorporeal HIFU can be proposed for wider clinical use. [Table: see text]