Transarterial (chemo)embolisation versus no intervention or placebo for liver metastases

The liver is affected by two of the most common groups of malignant tumours: primary liver tumours and liver metastases from colorectal carcinoma or other extrahepatic primary cancers. Liver metastases are significantly more common than primary liver cancer, and long-term survival rate after radical surgical treatment is approximately 50%. However, R0 resection (resection for cure) is not feasible in the majority of people; therefore, other treatments have to be considered. 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 hepatic artery can be achieved by administering a chemotherapeutic drug followed by vascular occlusive agents, and can lead to selective necrosis of the liver tumour while it may leave normal parenchyma virtually unaffected. This can also be performed without chemotherapy, which is called bland transarterial embolisation (TAE).

To assess the beneficial and harmful effects of TAE or TACE compared with no intervention or placebo in people with liver metastases.

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, and four more databases (December 2019). We also searched two trials registers and the US Food and Drug Administration database (September 2019).

Randomised clinical trials assessing beneficial and harmful effects of TAE or TACE compared with no intervention or placebo for liver metastases.

We followed standard Cochrane methodological procedures. We extracted information on participant characteristics, interventions, study outcomes, study design, and trial methods. Two review authors independently extracted data and assessed risk of bias. We assessed the certainty of evidence with GRADE. We resolved disagreements by discussion.

We included one randomised clinical trial with 61 participants (43 male and 18 female) with colorectal cancer with liver metastases: 22 received transarterial embolisation (TAE; hepatic artery embolisation), 19 received transarterial chemoembolisation (TACE; 5-fluorouracil hepatic artery infusion chemotherapy with degradable microspheres), and 20 received 'no active therapeutic intervention' as a control. Most tumours were synchronous, unresectable metastases involving up to 75% of the liver. Participants were followed for a minimum of seven months. The trial was at high risk of bias. Very-low-certainty evidence found inconclusive results for mortality at 44 months between the TAE and TACE versus no intervention groups (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.74 to 1.06; 61 participants). Local recurrence was reported in 10 participants without any details about the group allocation. Very-low-certainty evidence found little or no difference in mortality between the TAE and no intervention groups (RR 0.91, 95% CI 0.75 to 1.10; 42 participants). Median survival was 7 months from trial entry (range 2 to 44 months) in the TAE group and 7.9 months (range 1 to 26 months) in the control group, and 8.7 months after diagnosis (range 2 to 49 months) in the TAE group and 9.6 months (range 1 to 27 months) in the control group. The trial authors reported the differences were not statistically significant. There were no reported side effects in the control group. In the TAE group, 18 participants experienced short-term symptoms of 'post-embolisation syndrome', which were relieved with symptomatic treatment; one participant also had a local puncture site haematoma. Very-low-certainty evidence found little or no difference in mortality between the TACE and no intervention groups (RR 0.83, 95% CI 0.65 to 1.07; 39 participants). Median survival in the TACE group was 10.7 months (range 3 to 38 months) from trial entry, and 13.0 months (range 3 to 38 months) after diagnosis. The trial authors reported that differences between groups were not statistically significant. All participants experienced short-term nausea, with or without vomiting, immediately after treatment; one participant developed a wound infection, and one developed deep vein thrombosis. The trial did not measure failure to clear liver metastases, time to progression of liver metastases, tumour response measures, or health-related quality of life. Cancer Research Campaign, a non-profit organisation, provided a grant for the trial; Pharmacia Ltd. delivered the Port-a-Cath arterial delivery systems and degradable starch microspheres. We identified one ongoing trial comparing TACE plus chemotherapy versus chemotherapy alone in people with unresectable colorectal liver metastases who failed with first-line chemotherapy (NCT03783559).

Based on one, small randomised trial at high risk of bias, the evidence is very uncertain about the effect of TAE or TACE versus no active therapeutic intervention on mortality for people with liver metastases as the true effect may be substantially different. The trial did not measure failure to clear liver metastases, time to progression of liver metastases, tumour response measures, or health-related quality of life. Short-term, minor adverse events were recorded in the intervention groups only. Large trials, following current standards of conduct and reporting, are required to explore the benefits and harms of TAE or TACE compared with no intervention or placebo in people with resectable and unresectable liver metastasis.