Currently, the standard of care in curative intent for liver metastases remains hepatic surgery [1]. Nevertheless, many patients are not suitable for surgery due to tumor location, number of metastases and/or other comorbidities. For these patients thermal ablation is an accepted alternative, especially in primary and secondary liver tumors measuring less than 3 cm [1], [2], [3].

One of the major limitations of thermal ablation is that local tumor control decreases rapidly when tumor size is above 2 to 3 cm. It is well known that for long term local tumor control adequate safety ablation margins of 5 mm to 10 mm are mandatory [2]. This safety margin cannot be guaranteed for large tumors, since current thermal ablation techniques are limited in the energy that can be applied. Accordingly, there are limits to the size of the ablation zone. One of the reasons for this is the heat-sink effect, which leads to dissipation of the applied thermal energy, especially in well perfused organs such as the liver. To overcome this problem the combination of transarterial chemoembolization (TACE) with thermal ablation has been investigated especially in hepatocellular carcinomas (HCCs). Besides the local effect of chemotherapy, the idea of prior embolization is to minimize the heat-sink effect [4].

For HCCs above 3 cm in size, meta-analyses and randomized controlled trials demonstrated that additional TACE combined with thermal ablation has a favorable effect on local tumor control and overall survival [5], [6], [7]. For liver metastases a combination of TACE and thermal ablation has only been described in a few case series with a limited number of patients [8,9]. It remains unclear whether the synergistic effect of TACE and thermal ablation also applies to liver metastases.

The purpose of this study was to evaluate the safety and efficacy of TACE combined with percutaneous thermal ablation in patients with liver metastases 3 cm in diameter or larger.