Laparoscopic high-intensity focused ultrasound for renal tumours: a proof of concept study

Abstract

Study Type--Therapy (case series) Level of Evidence What's known on the subject? and What does the study add? Renal cancer is increasingly diagnosed when tumours are small and asymptomatic, during routine abdominal imaging. Whilst surgery is an effective and potentially curative option, it carries a significant risk of complications. Recent work suggests that thermally ablative therapies (RFA, cryotherapy, HIFU) may be suitable minimally invasive treatment options in selected patients. The success of extracorporeal HIFU has been limited by the abdominal wall and rib-cage limiting energy delivery. For this study, a purpose-built laparoscopic HIFU probe was designed to allow direct application of the transducer to the tumour surface, thus facilitating tumour destruction. Successful and accurate tumour destruction was demonstrated, paving the way for further clinical trials, subject to device modifications.

Objective: • To test and establish clinical proof of concept for a laparoscopic high-intensity focused ultrasound (HIFU) device that facilitates delivery of ultrasound by direct application of a probe to the tumour surface.

Patients and methods: • Twelve patients with renal tumours were treated with laparoscopic HIFU using a newly designed probe inserted via an 18-mm laparoscopic port. • HIFU treatment was targeted at a pre-defined proportion of the tumour and immediate laparoscopic partial or radical nephrectomy was then performed.

Results: • No tumour ablation was seen in the first five patients which made modifications in the treatment protocol necessary. After this, definite histological evidence of ablation was seen in the remaining seven patients. • The ablated zones were within the targeted area in all patients and no intra-lesional skipping was seen. • Subcapsular skipping was seen at the probe-tumour interface in two patients with viable tumour cells seen at microscopy. • One patient did not undergo surgical extirpation; subsequent biopsy revealed no viable tumour cells. • There were no intraoperative or postoperative complications directly related to HIFU therapy and patients have reached a mean (range) follow-up of 15 (8-24) months with no evidence of metastatic disease or late complications.

Conclusions: • Tumour ablation with laparoscopic HIFU is feasible. • Homogenous ablation can be achieved with no vital tissue within the targeted zone. • The technique is associated with low morbidity and may have a role in the definitive management of small tumours.