Combination of ablation and embolization for intermediate-sized liver metastases from colorectal cancer: what can we learn from treating primary liver cancer?

Abstract

Colorectal cancer liver metastases (CRLMs) are common. Treating CRLMs with thermal ablation can prolong survival, but compared to lesions smaller than 3 cm, local control rates and overall survival are relatively worse with larger, intermediate (3-5 cm) lesions. Local recurrence rates range between 1.7%-20.2% and 6.7%-68.9% for CRLMs less than 3 cm and greater than 3 cm, respectively. Worse outcomes are also present when ablating intermediate size hepatocellular carcinoma (HCC) and there are some pathological similarities with CRLMs, namely the presence of micrometastatic disease. Combining ablation with transarterial chemoembolization is more effective in treating intermediate-size HCC than ablation alone. A meta-analysis of robust randomized controlled trials demonstrated long-term improved survival with combination therapy compared to ablation alone (odds ratio at 1, 3 and 5 years of 2.74, 2.77 and 5.23, respectively). There is, however, minimal evidence for combination therapy in CRLMs, limited to a handful of studies that are predominantly retrospective and have heterogeneous inclusion criteria. Given the difficulty in successfully treating intermediate CRLMs, the strong evidence for combination therapy in intermediate HCC and potential pathological similarities, formal evaluation of combination treatment in CRLM is merited. This review highlights existing evidence for treatment of intermediate-size liver lesions and highlights where trials in CRLMs should focus.

Figure. a–f

Preprocedural axial CT (a) shows a 3.5 cm arterialized hepatocellular carcinoma (HCC) (circle). Digital subtraction angiogram (b) indicates the treatment position for transarterial chemoembolization (TACE). Unenhanced cone beam CT performed directly after TACE (c) shows contrast being entrapped between the beads in the target lesion. Follow-up MRI at 1 month (d) shows the lesion to be devascularized. In panel (e), the HCC had shrunk prior to treatment with microwave ablation and the hypoattenuating appearance post TACE helped allow visualization. Immediate post-procedural CT (f) shows an augmented ablation zone following TACE, with an appropriate margin. The patient remains disease-free at long-term follow-up.