Metastatic liver disease
A liver metastasis is a malignant tumor in the liver that has spread from another organ affected by cancer. The liver is a common site for metastatic disease because of its rich, dual blood supply (the liver receives blood via the hepatic artery and portal vein). Metastatic tumors in the liver are 20 times more common than primary tumors. In 50% of all cases the primary tumor is of the gastrointestinal tract, other common sites include the breast, ovaries, bronchus and kidney. Tumor emboli entering the sinusoids through the liver blood supply appear to be physically obstructed  by the Kupffer cells, but if tumor emboli are larger, they tend to become lodged in the portal venous branches. Treatment. Treatment can consist of surgery (hepatectomy), chemotherapy and/or therapies specifically aimed at the liver like radiofrequency ablation, transcatheter arterial chemoembolization, selective internal radiation therapy and irreversible electroporation. For most patients no effective treatment exists because both lobes are usually involved, making surgical resection impossible. Younger patients with metastases from colorectal cancer confined to one lobe of the liver and up to 4 in number may be treated by partial hepatectomy. In selected cases, chemotherapy may be given systemically or  via hepatic artery. In some tumors, notably those arising from the colon and rectum, apparently solitary metastases or metastases to one or other lobes may be resected. A careful search for other metastases is required, including local recurrence of the original primary tumor (e.g., via colonoscopy) and dissemination elsewhere (e.g., via CT of the thorax). 5-year survival rates of 30-40% have been reported following resection. When resection for cure is not possible (R0 resection), percutaneous ethanol injection has been suggested to dehydrate and kill the tumour cells, however there is not enough evidence to determine the effectiveness and  safety of this approach.