Patients with unresectable primary or secondary malignancies of the liver have limited treatment options which often only give a small survival benefit. RFA has been demonstrated to be effective in local tumour eradication and to extend patient survival. In this study RFA aspiration will be used to treat unresectable primary or secondary tumours of the liver. RFA will be used to develop a shell of tissue destruction around the tumour, with aspiration removing tissue and fluid from the centre of the lesion. The potential advantages of aspirating during ablation could be to reduce aerosol spread of tumour within the liver parenchyma and peritoneum. Additionally, aspirating the ablated tissue may reduce the incidence of systemic side effects related to RFA when larger lesions are treated. This study would establish the safety and efficiacy of RFA aspiration in the treatment of unresectable primary/secondary malignancies of the liver.