Cryosurgery and radiofrequency ablation for unresectable colorectal liver metastases
Introduction
Until now resection offers the highest chance of cure in patients with colorectal liver metastases. After resection a 5-year survival rate of up to 40% is described.1 However, only 10–15% of patients with liver metastases are eligible for resection. Extrahepatic disease, patient factors and tumour characteristics (number and site of metastases) can result in unresectable disease.2, 3, 4
When number and localization of metastases are the cause of unresectable disease, local ablative techniques such as cryosurgical ablation (CSA) and radiofrequency ablation (RFA) may offer an alternative treatment option with possible prolongation of survival.
Cryosurgery is a long known ablative technique in which the application of extreme low temperatures to tumour tissue leads to protein denaturation and cellular dehydration, eventually resulting in tumour cell destruction.5, 6 Several studies have described the feasibility and efficacy of cryosurgery in the treatment of unresectable colorectal liver metastases.7, 8, 9 More recently, radiofrequency ablation has been proposed as a successful treatment option in case of unresectable colorectal liver metastases. Hyperthermia with temperatures above 50 °C will lead to immediate cell death and tumour destruction. Different groups have reported on the effects and safety of radiofrequency ablation, suggesting superior results compared to cryosurgery.10, 11, 12, 13
Morbidity and efficacy of these different local tumour ablative techniques are, however, difficult to compare because most reports include different patient selection criteria, different treatment protocols and sometimes even different types of tumour. Accordingly, the extent of liver disease treated in the different series varies significantly which directly influences data on morbidity, disease free and overall survival.14, 15, 16 Controlled studies comparing both techniques in well-defined selected patients are lacking.
The aim of this study is to compare the immediate effects and long-term results of cryoablation and radiofrequency therapy in a uniform group of patients with unresectable colorectal liver metastases.
Section snippets
Patient characteristics
Between January 1994 and June 2003, a consecutive series of 58 patients was identified from our prospective colorectal liver metastases database that underwent local ablative therapy for unresectable liver metastases.
Patients with documented colorectal liver metastases who met the following criteria were considered for local ablative therapy: (1) Metastases confined to the liver and judged unresectable due to extent of disease or localization, (2) CSA or RFA alone or in combination with
Surgical procedure
Amongst all lesions encountered in 58 patients, a total 69 lesions was treated by cryosurgery and 72 by RFA. The characteristics of the lesions treated by local tumour ablation are given in Table 3. The number of nodules per patient treated by cryosurgery ranged from 1 to 7, with a median of two. The number of RFA lesions treated per patient varied from 1 to 8, with also a median of two (p=0.52). In the CSA group 22 of 69 lesions were greater than or equal to 4 cm compared to six out of 72 in
Discussion
For patients with colorectal liver metastases surgical resection offers the best chance for cure. In most patients with colorectal liver metastases, however, resection cannot be performed either because of extensive liver involvement or unfavourable located tumour deposits. It is in these patients in whom local ablative techniques, such as cryosurgery or radiofrequency, may be helpful to achieve local tumour control potentially leading to prolongation of survival.7, 8, 9, 10, 11, 12, 13
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