Microwave ablation achieved 88.9% local control in colorectal liver metastases one year after treatment, with larger ablation margins significantly reducing the risk of local failure, according to the European CIEMAR registry of 491 patients across 30 centers in 11 countries.
- Microwave ablation achieved 88.9% local control in colorectal liver metastases at one-year follow-up
- The CIEMAR registry included 491 patients treated at 30 centers across 11 European countries
- Larger ablation margins were associated with lower odds of local failure
- The PROMETHEUS study found that margins of at least 5 mm improved local control in hepatocellular carcinoma
- AI-based workflows are being developed to automate margin assessment and improve measurement reliability
Two studies presented at CIRSE 2026 linked adequate ablation margins to better liver tumor control. Measuring those margins consistently remains a challenge.
Microwave ablation of colorectal liver metastases achieved local control in 88.9%
Dr. Philippe L. Pereira: “Confirmation software should be part of your equipment.”CIRSE
Dr. Philippe L. Pereira, of SLK-Kliniken in Heilbronn, Germany, presented the findings as evidence of how ablation performs across European centers. The related paper in CardioVascular and Interventional Radiology included 491 patients treated at 30 centres in 11 countries.
The registry adds “prospective, robust, and long-term follow-up data,” Pereira said at CIRSE 2026. He particularly advocated confirmation software for operators performing fewer procedures.
PROMETHEUS: Assessing the 5-mm margin
Gonnie van Erp: “We still see interobserver differences in margin assessment.”CIRSE
Gonnie van Erp, MSc, of Leiden University Medical Center in Leiden, Netherlands, reported that margins of at least 5 mm were associated with improved local control, “providing a quantitative threshold to guide intraprocedural decision making.”
Margins of 0–5 mm also had low progression rates. Van Erp considered them potentially acceptable “only when immediate reablation is not readily feasible.” Obtaining reliable measurements remains difficult. Respiratory motion complicated alignment of scans, and registration failures prevented assessment in some patients.
“We still see interobserver differences in margin assessment,” van Erp said. The team is investigating automation: “We’re also working on an AI-based workflow now,” she added.
An international consensus in The Lancet Oncology already recommends assessing and documenting margins for every treated liver tumor.
