Treatment of liver metastases, an update on the possibilities and results

Long-term results after liver resection for colorectal liver metastases show 5-year survival rates between 35 and 40%. However, only a limited number of patients appear to be candidates for resection, far more patients prove to have unresectable disease. Present challenges in liver surgery for colorectal metastases are to improve patient selection, to increase the resectability rate and to improve survival by multimodality treatment approaches. The variables most consistently associated with a poor prognosis and tumour recurrence are tumour-positive resection margins and the presence of extra-hepatic disease. Hence, patient selection and preoperative staging should concentrate on accurate imaging of the liver lesions and the detection of extrahepatic disease. For liver imaging, spiral computed tomography (CT) scan or magnetic resonance imaging (MRI), supplemented by intra-operative ultrasound, are currently regarded as the best methods for evaluating the anatomy and resectability of colorectal liver metastases. Extrahepatic disease should be investigated by spiral CT of the chest and abdomen and when possible by 2-fluouro-2-deoxy-D-glucose-positron emission tomography (FDG-PET). Resection remains the gold standard for the surgical treatment of colorectal liver metastases. In experienced centres, resection is a safe procedure and mortality rates are below 5%. The aim of resection should be to obtain tumour-negative resection margins. Edge cryosurgery should be considered in cases where very close resection margins are anticipated. The role of adjuvant chemotherapy after resection is still controversial, although two recent studies show a clear benefit. For the moment, local tumour ablative therapies such as cryotherapy and radiofrequency therapy should be considered as an adjunct to hepatic resection in those cases in which resection can not deal with all of the tumour lesions. In these cases, there seems a beneficial effect of a combined treatment consisting of resection and local tumour ablation. At this stage, there are no randomised data that local tumour ablation is as effective as resection. For a selected group of patients with unresectable liver metastases, there may be a chance to turn unresectable disease to resectable disease by aggressive neo-adjuvant chemotherapy or portal vein embolisation. For patients with unresectable disease, many different chemotherapy schedules may be used based on systemic drug administration. Regional chemotherapy and isolated liver perfusion should only be used within a study design.