Predictive Factors for Local Recurrence after Intraoperative Microwave Ablation for Colorectal Liver Metastases

Abstract

This study aimed to clarify local recurrence (LR) predictive factors following intraoperative microwave ablation (MWA) for colorectal liver metastases. The data from 195 patients with 1392 CRLM lesions, who were preoperatively diagnosed by gadolinium-enhanced MRI with diffusion-weighted imaging and dynamic CT and treated with intraoperative MWA (2450 MHz) with or without hepatectomy, from January 2005 to December 2019, were retrospectively reviewed and analyzed using logistic regression. In addition, the margins were measured on contrast-enhanced CT 6 weeks post-ablation. Overall, 1066 lesions were ablated. The LRs occurred in 44 lesions (4.1%) among 39 patients (20.0%). The multivariate analysis per patient showed that tumor size > 20 mm and ablation margin < 5 mm were significant predictors for LR. Furthermore, multivariate analysis per lesion revealed that segments 1, 7, and 8 and tumor size > 15 mm, ablation margin < 5 mm, tumor size > 20 mm, and proximity to the Glisson were significant LR predictors. Finally, the outcome of this study may help determine indications for MWA.

A Review of Resection and Surgical Ablation for Primary and Secondary Liver Cancers

“…Tumor size and ablation margin—frequently determined by cross-sectional imaging obtained a few weeks after the procedure—have been identified as significant factors in incomplete ablation and local recurrence, which historically has been reported to be as low as 4% with MWA. 35 36 Retrospective analyses and meta-analyses have regularly evaluated this clinical question. One recent meta-analyses of 740 patients from 10 retrospective studies of ablation in HCC demonstrated significantly lower tumor recurrence rates and greater 5-year disease-free survival in the surgical ablation group despite larger tumor sizes in this group.…”

“…Increasing tumor size is often cited as a risk factor for recurrence, although the ablation zone margin may be a better measure of recurrence risk instead of initial tumor size. 25,35…”

Percutaneous image‐guided ablation for hepatic metastases

“…For CLM, it has been shown that minimum ablation margins of at least 5 mm and ideally 10 mm are critical for prolonged local tumour progression-free survival, regardless of the thermal ablation modality used (RFA or MWA). 5,[12][13][14][15]17,18,[55][56][57][58] This is referred to as an A0 ablation, analogous to surgical resections with clear microscopic margins (R0) and is essential to provide local cure and serve as a surgical alternative, since the majority of intrahepatic micrometastases are within 1 cm of the gross tumour. 59 When a 10 mm minimal margin can be achieved, local tumour progression free-survival exceeds 95% and can offer a chance for local cure similar to surgery, without the associated morbidity.…”

“…Multiple studies have proven that the most important technical factor for local tumour control is ablation with adequate margins. For CLM, it has been shown that minimum ablation margins of at least 5 mm and ideally 10 mm are critical for prolonged local tumour progression‐free survival, regardless of the thermal ablation modality used (RFA or MWA) 5,12–15,17,18,55–58 . This is referred to as an A0 ablation , analogous to surgical resections with clear microscopic margins (R0) and is essential to provide local cure and serve as a surgical alternative, since the majority of intrahepatic micrometastases are within 1 cm of the gross tumour 59 .…”

Prediction model for local tumor progression following microwave ablation treatment of early-stage lung cancer

“…Prior work studied factors that are statistically significant for prediction of LTP after an ablation treatment, mostly focused on liver ablation procedures. These factors include minimal ablation margins, volume of insufficient coverage (unablated tumor volume), tumor size, tumor number, tumor subtype (e.g., adenocarcinoma and squamous cell carcinoma), adjoining with blood vessels of diameter >= 3 mm, and tumor location [1], [2], [3], [4], [5], [6]. Staal et al also applied multiple statistical radiomics (e.g., HU uniformity, mean, and kurtosis) of both ablation zone and peri-ablation zone to predict LTP for colorectal liver metastases in the liver [3].…”