International Study on Treatment of Patients With Metastatic Colorectal Liver Lesions Patients With IRE

Inclusion Criteria: * Patients aged 18 years and over, able to provide informed consent and with histological confirmation of a diagnosis of colorectal cancer from primary tumour. * Liver lesions demonstrating radiological characteristics (on magnetic resonance scan) of colorectal hepatic metastases without requirement for biopsy. In the setting of an intact liver, patients with up to four metastases ≤ 4cm in size are eligible for inclusion. In the setting of proposed resection plus ablation, up to two metastases ≤ 4cm in size. In the setting of recurrence after prior hepatectomy up to two metastases ≤ 4cm in size. * Eastern Co-operative Oncology Group (ECOG) Score ≤ 2. * Rockwood Frailty Score ≤ 3. * Serum bilirubin \< 30 µmol/L. * Serum creatinine \< 150 µmol/L. * Up to two lung metastases (\< 2cm in size permitted at enrolment). * Prior treatment with at least one course of systemic chemotherapy (± biologic agent) mandated. Chemotherapy protocol is not specified and is at clinician discretion. * Primary rectal tumour can remain in situ treated with radiotherapy/chemoradiotherapy according to tumour board recommendations. Primary colonic tumour can remain in situ. * No prior hepatic tumour ablation Exclusion Criteria: * Patients involved in other research studies. * Inability to give informed consent. * Patients who are pregnant. * Accepted exclusions to IRE from consensus criteria including: * Platelet count \< 50x109 U/L. * International normalised ratio (INR) for blood clotting \> 1.7. * Prior hepatic tumour ablation. Cardiovascular fitness related exclusions: * History of ventricular arrhythmia. * Implanted pacemaker or defibrillator. * Congestive cardiac failure NYHA Class ≥ 3. Tumour-related exclusions: * Tumour ≥ 4 cm in size. * Advanced multi-site metastatic cancer (any of the following): peritoneal metastases (M1c), bone metastases, \> 2 lung metastases, all segment involvement multiple liver metastases. * Jaundice (serum bilirubin \> 30 µmol/L). * MDT/tumour recommends use of thermal ablation instead of IRE for any given lesion.