Transarterial (chemo)embolisation versus systemic chemotherapy for colorectal cancer liver metastases

Background The liver is affected by two groups of malignant tumours: primary liver cancers and liver metastases. Liver metastases are significantly more common than primary liver cancer, and five‐year survival after radical surgical treatment of liver metastases ranges from 28% to 50%, depending on primary cancer site. However, R0 resection (resection for cure) is not feasible in most people; therefore, other treatments have to be considered in the case of non‐resectability. One possible option is based on the concept that the blood supply to hepatic tumours originates predominantly from the hepatic artery. Transarterial chemoembolisation (TACE) of the peripheral branches of the hepatic artery can be achieved by administering a chemotherapeutic drug followed by vascular occlusive agents and can lead to selective necrosis of the cancer tissue while leaving normal liver parenchyma virtually unaffected. The entire procedure can be performed without infusion of chemotherapy and is then called bland transarterial embolisation (TAE). These procedures are usually applied over a few sessions. Another possible treatment option is systemic chemotherapy which, in the case of colorectal cancer metastases, is most commonly performed using FOLFOX (folinic acid, 5‐fluorouracil, and oxaliplatin) and FOLFIRI (folinic acid, 5‐fluorouracil, and irinotecan) regimens applied in multiple sessions over a long period of time. These therapies disrupt the cell cycle, leading to death of rapidly dividing malignant cells. Current guidelines determine the role of TAE and TACE as non‐curative treatment options applicable in people with liver‐only or liver‐dominant metastatic disease that is unresectable or non‐ablatable, and in people who have failed systemic chemotherapy. Regarding the treatment modalities in people with colorectal cancer liver metastases, we found no systematic reviews comparing the efficacy of TAE or TACE versus systemic chemotherapy. Objectives To evaluate the beneficial and harmful effects of transarterial embolisation (TAE) or transarterial chemoembolisation (TACE) compared with systemic chemotherapy in people with liver‐dominant unresectable colorectal cancer liver metastases. Search methods We searched the Cochrane Hepato‐Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, and three additional databases up to 4 April 2024. We also searched two trials registers and the European Medicines Agency database and checked reference lists of retrieved pu