William Robert Lees MBBS, Presenter: Nothing to Disclose

Alison R. Gillams MBCHB, Abstract Co-Author: Nothing to Disclose

Radiofrequency ablation has proved to be highly successful in the management of colorectal cancer liver metastases, but a few problems remain. Impedance roll off limits the amount of delivered energy. Local recurrence rates of up to 30% are reported and local complications caused by the RF current pathway can occur. An experimental microwave system is capable of delivering up to 100W directly in tissue via a 2.3 mm diameter needle. This study is designed to compare the effectiveness of RFA and Microwave ablation (MTA) in patients with multiple CRC liver metastases.

In patients with inoperable CRC liver metastases under 5cm diameter individual lesions are randomized to treatment with either RFA or MTA using standard treatment protocols under a combination of CT and US guidance. 54 patients will be entered into this study (power 0.8). Study end points are 1. percentage necrosis achieved in each lesion and 2. local recurrence rates observed in follow up. Subsidary notables are size of ablation zone/time, local complications and any technical difficulties encountered.

12 patients have been treated to date. Of 23 tumours treated with microwaves and 21 treated with RFA follow up scanning has shown 100 necrosis in all tumours. Treatment times have been 2-4 minutes with Microwaves and 4-8 minutes with RFA. The heat sink tumour protective effect seen with RFA has not been apparent with MTA. There have been no significant complications or significant post procedure pain.

MTA appears very promising in comparison to RFA. The rapid delivery of large quantities of heat allows the build up of large ablation zones without the impedance problems experienced with RFA. No MTA specific complications have been observed as yet.

W.R.L.,A.R.G.: The microwave equipment used in this study was provided by Microsulis Ltd.

Lees, W, Gillams, A, A Comparison of Radiofrequency and Microwave Ablation in the Treatment of Patients with Multiple Colorectal Cancer Liver Metastases.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4417746.html