The guidelines for metastatic colorectal cancer crudely state that the best local treatment should be selected from a 'toolbox' of techniques according to patient- and treatment-related factors. We created an interdisciplinary, consensus-based algorithm with specific resectability and ablatability criteria for the treatment of colorectal liver metastases (CRLM). To pursue consensus, members of the multidisciplinary COLLISION and COLDFIRE trial expert panel employed the RAND appropriateness method (RAM). Statements regarding patient, disease, tumor and treatment characteristics were categorized as appropriate, equipoise or inappropriate. Patients with ECOG≤2, ASA≤3 and Charlson comorbidity index ≤8 should be considered fit for curative-intent local therapy. When easily resectable and/or ablatable (stage IVa), (neo)adjuvant systemic therapy is not indicated. When requiring major hepatectomy (stage IVb), neo-adjuvant systemic therapy is appropriate for early metachronous disease and to reduce procedural risk. To downstage patients (stage IVc), downsizing induction systemic therapy and/or future remnant augmentation is advised. Disease can only be deemed permanently unsuitable for local therapy if downstaging failed (stage IVd). Liver resection remains the gold standard. Thermal ablation is reserved for unresectable CRLM, deep-seated resectable CRLM and can be considered when patients are in poor health. Irreversible electroporation and stereotactic body radiotherapy can be considered for unresectable perihilar and perivascular CRLM 0-5cm. This consensus document provides per-patient and per-tumor resectability and ablatability criteria for the treatment of CRLM. These criteria are intended to aid tumor board discussions, improve consistency when designing prospective trials and advance intersociety communications. Areas where consensus is lacking warrant future comparative studies.

https://www.mdpi.com/2072-6694/12/7/1779/pdf

Resectability and Ablatability Criteria for the Treatment of Liver Only Colorectal Metastases : Multidisciplinary Consensus Document from the COLLISION Trial Group

Image-Guided Thermal Ablation for Colorectal Liver Metastases.

The aim of this study was to assess safety, efficacy and survival outcomes of repeat thermal ablation as compared to repeat partial hepatectomy in patients with recurrent colorectal liver metastases (CRLM). This Amsterdam Colorectal Liver Met Registry (AmCORE) based study of two cohorts, repeat thermal ablation versus repeat partial hepatectomy, analyzed 136 patients (100 thermal ablation, 36 partial hepatectomy) and 224 tumors (170 thermal ablation, 54 partial hepatectomy) with recurrent CRLM from May 2002 to December 2020. The primary and secondary endpoints were overall survival (OS), distant progression-free survival (DPFS) and local tumor progression-free survival (LTPFS), estimated using the Kaplan-Meier method, and complications, analyzed using the chi-square test. Multivariable analyses based on Cox proportional hazards model were used to account for potential confounders. In addition, subgroup analyses according to patient, initial and repeat local treatment characteristics were performed. In the crude overall comparison, OS of patients treated with repeat partial hepatectomy was not statistically different from repeat thermal ablation (p = 0.927). Further quantification of OS, after accounting for potential confounders, demonstrated concordant results for repeat local treatment (hazard ratio (HR), 0.986; 95% confidence interval (CI), 0.517-1.881; p = 0.966). The 1-, 3- and 5-year OS were 98.9%, 62.6% and 42.3% respectively for the thermal ablation group and 93.8%, 74.5% and 49.3% for the repeat resection group. No differences in DPFS (p = 0.942), LTPFS (p = 0.397) and complication rate (p = 0.063) were found. Mean length of hospital stay was 2.1 days in the repeat thermal ablation group and 4.8 days in the repeat partial hepatectomy group (p = 0.009). Subgroup analyses identified no heterogeneous treatment effects according to patient, initial and repeat local treatment characteristics. Repeat partial hepatectomy was not statistically different from repeat thermal ablation with regard to OS, DPFS, LTPFS and complications, whereas length of hospital stay favored repeat thermal ablation. Thermal ablation should be considered a valid and potentially less invasive alternative for small-size (0-3 cm) CRLM in the treatment of recurrent new CRLM. While, the eagerly awaited results of the phase III prospective randomized controlled COLLISION trial (NCT03088150) should provide definitive answers regarding surgery versus thermal ablation for CRLM.

https://www.mdpi.com/2072-6694/13/11/2769/pdf

Thermal Ablation Compared to Partial Hepatectomy for Recurrent Colorectal Liver Metastases: An Amsterdam Colorectal Liver Met Registry (AmCORE) Based Study.

Image-guided ablation can provide effective local tumor control in selected patients with CLM. A randomized controlled trial suggested that radiofrequency ablation combined with systemic chemotherapy resulted in a survival benefit for patients with unresectable CLM, compared to systemic chemotherapy alone. For small tumors, ablation with adequate margins can be considered as an alternative to resection. The improvement of ablation technologies can allow the treatment of tumors close to major vascular structures or bile ducts, on which the applicability of thermal ablation modalities is challenging. Several factors affect the outcomes of ablation, including but not limited to tumor size, number, location, minimal ablation margin, RAS mutation status, prior hepatectomy, and extrahepatic disease. Further understanding of the impact of tumor biology and advanced imaging guidance on overall patient outcomes might help to tailor its application, and improve outcomes of image-guided ablation.

https://www.mdpi.com/2072-6694/13/16/3926/pdf

Image-Guided Ablation for Colorectal Liver Metastasis: Principles, Current Evidence, and the Path Forward

The prognosis of radiofrequency ablation versus hepatic resection for patients with colorectal liver metastases: a systematic review and meta-analysis based on 22 studies.

Introduction Many previous studies comparing liver resection versus thermal ablation for colorectal cancer liver metastases (CRCLM) are subject to severe selection bias. The aim of this study was to compare survival after microwave ablation (MWA) versus liver resection for CRCLM in a population-based cohort study using propensity score analysis to reduce confounding by indication. Methods All patients undergoing liver resection or MWA as a first intervention for CRCLM measuring ≤ 3 cm between 2013 and 2016 in Sweden were included from a nationwide registry. Treatment effect was estimated after propensity score matching, adjusting for patient and tumour factors known to affect the choice of treatment approach. Descriptive, regression and survival statistics were applied. Results The unmatched cohorts (82 MWA patients, 645 resection patients) differed significantly regarding age, American Society of Anaesthesiologists class, Charlson comorbidity index, primary tumour location, number of metastases and previous chemotherapy, with 3-year overall survival (OS) favouring resection over MWA (76 and 69%, p = 0.005). After propensity score matching (70 MWA patients, 201 resection patients), no difference in 3-year OS was shown between resected and ablated patients (76% and 76%, p = 0.253), with a median OS of 54.7 (95% confidence interval 48.6 - 60.9) months and 48 (40.1–56.1) months, respectively. Conclusion After adjusting for factors known to affect treatment choice, no significant difference in OS was shown after MWA versus resection for CRCLM. This supports the potential role of MWA as a valid first-line treatment for patients with small CRCLM.

Gabriella Dal

Papers

Microwave ablation versus resection for colorectal cancer liver metastases - A propensity score analysis from a population-based nationwide registry.