COLLISION Trial Overview

Surgical resection is the historic gold standard for treating isolated colorectal liver metastases (CRLM). However, a recent multicenter, phase 3 trial led by the Dutch Colorectal Cancer Group is challenging this paradigm. This study explored the potential of thermal ablation as a similarly efficacious, safer, and more cost-effective alternative to resection. This post aims to highlight the key findings presented about this study and its potential implications for CRLM treatment.

This trial involved 341 patients with small-size (≤3 cm) resectable CRLM from 14 centers across the Netherlands, Belgium, and Italy. The inclusion criteria involved patients with ≤10 CRLM, no extrahepatic disease, and ECOG 0-2. These patients were randomly assigned to either surgical resection or thermal ablation, with preference for minimally invasive techniques (laparoscopic and percutaneous approaches). The primary outcome was overall survival (OS), while secondary outcomes included local and distant progression-free survival (PFS), local control, safety, hospital stay length, quality of life, and cost-effectiveness.

The findings of this landmark trial suggest that thermal ablation might be the new gold standard for small-size CRLM. Thermal ablation appears to have non-inferior efficacy compared to surgical resection as demonstrated by similar OS and PFS, and also possibly even improved local control of disease. Thermal ablation was also safer than surgical resection, with less associated mortality and adverse events. Additionally, in this era of strained healthcare resources, the shortened hospital stay associated with ablation is especially pertinent.

The primary endpoint of overall survival is also a particular strength of this study, as this is likely a more clinically relevant endpoint than progression-free survival. An interesting caveat is that intraoperative ablations were included in the ablation group, which could possibly confound the applicability of these findings to percutaneous ablation only. These findings have also only been published in an abstract format and this study still needs to be published in full in a peer-reviewed journal.

As always, despite these promising findings, it will take time for practice patterns to change and more evidence may be needed for ablation to be adopted as the new gold standard by the medical community. Regardless, it is important that both patients and physicians become more aware of ablation as an option for colorectal cancer metastases and the crucial role that endovascular and interventional surgeons (EVIS) have in oncologic therapy. However, this also requires EVIS who practice interventional oncology to have longitudinal clinics to follow these patients and ensure they are receiving the most appropriate and comprehensive treatment for their disease.

These findings were presented at the ASCO Annual Meeting. However, peer-reviewed journal publication and further validation are needed prior to implementation of such protocols.

Cover Image Source: https://ascopubs.org/doi/10.1200/JCO.21.02505