Abstract
PurposeTo assess safety and outcome of radiofrequency ablation (RFA) and microwave ablation (MWA) as compared to systemic chemotherapy and partial hepatectomy (PH) in the treatment of colorectal liver metastases (CRLM).MethodsMEDLINE, Embase and the Cochrane Library were searched. Randomized trials and comparative observational studies with multivariate analysis and/or matching were included. Guidelines from National Guideline Clearinghouse and Guidelines International Network were assessed using the AGREE II instrument.ResultsThe search revealed 3530 records; 328 were selected for full-text review; 48 were included: 8 systematic reviews, 2 randomized studies, 26 comparative observational studies, 2 guideline-articles and 10 case series; in addition 13 guidelines were evaluated. Literature to assess the effectiveness of ablation was limited. RFA + systemic chemotherapy was superior to chemotherapy alone. PH was superior to RFA alone but not to RFA + PH or to MWA. Compared to PH, RFA showed fewer complications, MWA did not. Outcomes were subject to residual confounding since ablation was only employed for unresectable disease.ConclusionThe results from the EORTC-CLOCC trial, the comparable survival for ablation + PH versus PH alone, the potential to induce long-term disease control and the low complication rate argue in favour of ablation over chemotherapy alone. Further randomized comparisons of ablation to current-day chemotherapy alone should therefore be considered unethical. Hence, the highest achievable level of evidence for unresectable CRLM seems reached. The apparent selection bias from previous studies and the superior safety profile mandate the setup of randomized controlled trials comparing ablation to surgery.
Highlights
Colorectal cancer is the second most common cause of cancer-related death in developed countries and the third most common malignancy worldwide [1]
The results from the EORTC-CLOCC trial, the comparable survival for ablation ? partial hepatectomy (PH) versus PH alone, the potential to induce long-term disease control and the low complication rate argue in favour of ablation over chemotherapy alone
The search strategies and inclusion criteria were based on the following PICOS question: P: patients with resectable and unresectable colorectal liver metastases (CRLM); I: radiofrequency ablation (RFA) and microwave ablation (MWA); C: for resectable disease PH and for unresectable disease systemic chemotherapy; O: critical endpoints were overall survival (OS), complications and quality of life (QoL), important endpoints were diseasefree survival (DFS), local progression-free survival (LPFS), and ablation-site recurrence rate (ASR); S:, randomized studies, controlled studies, comparative observational studies with multivariate analysis and/or matching, non-comparative studies if an insufficient number of comparative studies was found
Summary
Colorectal cancer is the second most common cause of cancer-related death in developed countries and the third most common malignancy worldwide [1]. Recent studies [13,14,15,16] have reported similar survival for patients treated with thermal ablation or PH, interventional radiology and surgical oncology communities generally state that thermal ablation cannot be considered an alternative to PH They recommend the use of open, laparoscopic or percutaneous RFA and MWA for small CRLM (B 3 cm) in patients who are unsuitable for resection due to (1) an impaired general health status (age, comorbidities), (2) a history of extensive abdominal surgery, (3) the presence of lesions with an unfavourable location or (4) an insufficient future liver remnant to resect all lesions [11, 17, 18].
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