Ablation Of Colorectal Liver Metastases Research Articles

Does microwave ablation provide comparable clinical outcomes to surgical resection for colorectal liver metastasis? A systematic review and meta-analysis

Presenter: Rebecca Platoff MD | Cooper University Hospital Background: Microwave ablation (MWA) is the preferred ablation tool over radiofrequency ablation (RFA) for resectable liver lesions due to the improved heat sink effect. Previous studies comparing efficacy of ablation compared to surgery have been heterogeneous, including both RFA and MWA when comparing versus surgical resection. However, there is a paucity of data regarding comparison using only MWA versus surgical resection for lesions < 3cm. We aim to compare outcomes after surgical resection versus microwave ablation for colorectal liver metastases by performing a systematic review of the existing literature. Methods: A systematic literature search was performed of PubMed Medline, Embase, and Cochrane Central to report all studies of patients with colorectal liver metastases undergoing microwave ablation or surgical resection. Patients undergoing other therapies, including radiofrequency ablation, were excluded. All study types were included except for case reports and studies in the pediatric population. Results: Of 727 studies reviewed, a full-text review of 60 studies was performed, of which four directly compared microwave ablation and surgical resection for colorectal liver metastases (Table). One study randomly assigned patients to ablative versus surgical treatment, while the other three used retrospective review. Shibata et al, which utilized random assignment, found no statistically significant difference in OS (27 months for MVA vs 25 months for resection, p=0.83). Tinguely et al. originally compared unmatched groups and found improved survival in the group undergoing resection (76% vs 69% at 3 years, p=0.005). After propensity matching, the 3-year OS between the groups disappeared (76% vs 76%, p=0.253). Philips et al. reported increased median survival in the surgery group (43.9 mo vs 37.6 mo, p=0.035) and did not perform matching. Song et al. reported no significant difference in OS or DFS between the groups but did not supply raw data. Complications were generally noted to be higher in the surgical group, with Song et al. reporting a complication rate of 26.5% in the resection group compared with 0% for the MVA group (p=0.003). Tinguely et al. also reported a higher complication rate in the surgery group (16.4% vs 7%, p=0.046). Shibata found a similar complication rate between the two groups (18.8% vs 14.3%, p=0.87), and Philips did not provide this data. Excluded articles did not meet inclusion criteria (25), did not compare the two groups of interest (13), were review articles or guidelines without original data to present (9), or were randomized trials proposed or in the early stages (3). Conclusion: For select patients with colorectal liver metastases, microwave ablation (MVA) offers similar overall survival (OS) and disease-free survival (DFS) when compared to surgical resection alone and appears to provide a lower complication rate. MVA for CLM is currently offered for both resectable lesions that are small (≤3cm) and those potentially resectable or bilateral lesions. MVA is often performed in combination with hepatic resection, with favorable results.

Predicting post-hepatectomy liver failure and complication burden after resection and/or ablation for colorectal liver metastases

Presenter: Hordur Kolbeinsson MD | Spectrum Health Butterworth Hospital Background: Post-hepatectomy liver failure (PHLF) is a significant contributor of post-operative mortality after liver resection. This study sought to identify liver specific factors that predict post-hepatectomy liver failure or overall complication burden in patients undergoing liver resection or ablation for colorectal liver metastases. Methods: This is a retrospective analysis of all patients that underwent resection and/or ablation of colorectal liver metastases between January 2007 and June 2019. Pre-operative Model for End-Stage Liver Disease score was calculated. Volume of liver resected was split into quartiles for analysis. Post-operative complication burden is depicted with the Comprehensive Complication Index (CCI). Logistic regression, Spearman’s rho test, Kruskal-Wallis ANOVA, Mann-Whitney test and multiple regression were utilized to assess relationships to post-operative outcomes. Results: 227 patients were included in the study, mean age was 60.6 (SD+11.0) and 58.2% were male. Of those, 159 (71.0%) underwent liver resection alone, 43 (18.9%) had combination resection/ablation and 25 (11.0%) had ablation alone. Major resection (trisegmentectomy) was performed in 22 (9.7%) while 94 (41.4%) had a lobectomy and 86 (37.9%) wedge resection with or without ablation. Nineteen (8.4%) patients suffered from PHLF (any grade), of which 4 (1.8%) had grade B or C. Median preoperative MELD score was 6 (IQR: 1) and post-operative CCI was 22.6 (IQR: 38.2). Preoperative MELD score did not correlate with PHLF (p=0.11) or CCI (p=0.82). However, highest quartile volume liver resected (median 39.2 cm3, IQR: 28.1) correlated with higher rate of PHLF (22%, p0.3). Conclusion: Pre-operative MELD score does not predict post-hepatectomy liver failure or overall complication burden in patients without cirrhosis. Higher volume of liver resected correlates with higher complication burden post-operatively.

Perioperative Radiofrequency Ablation or Microwave Ablation of Colorectal Liver Metastases: A Single Centre Experience

Introduction: Radiofrequency ablation (RFA) and microwave ablation (MWA) are generally accepted to treat colorectal liver metastases (CRLM) with a curative intent. MWA is considered to have better outcomes than RFA but true comparing data are scarce.

Microwave Ablation of Colorectal Liver Metastases Guided by US-PET/CT Fusion Imaging: A Case Report

Microwave Ablation of Colorectal Liver Metastases Guided by US-PET/CT Fusion Imaging: A Case Report

Laparoscopic hepatectomy versus microwave ablation for colorectal liver metastases: a retrospective analysis

Laparoscopic hepatectomy versus microwave ablation for colorectal liver metastases: a retrospective analysis

Hospital variation in combined liver resection and thermal ablation for colorectal liver metastases and impact on short-term postoperative outcomes: a nationwide population-based study

BackgroundCombining resection and thermal ablation can improve short-term postoperative outcomes in patients with colorectal liver metastases (CRLM). This study assessed nationwide hospital variation and short-term postoperative outcomes after combined resection and ablation. MethodsIn this population-based study, all CRLM patients who underwent resection in the Netherlands between 2014 and 2018 were included. After propensity score matching for age, ASA-score, Charlson-score, diameter of largest CRLM, number of CRLM and earlier resection, postoperative outcomes were compared. Postoperative complicated course (PCC) was defined as discharge after 14 days or a major complication or death within 30 days of surgery. ResultsOf 4639 included patients, 3697 (80%) underwent resection and 942 (20%) resection and ablation. Unadjusted percentage of patients who underwent resection and ablation per hospital ranged between 4 and 44%. Hospital variation persisted after case-mix correction. After matching, 734 patients remained in each group. Hospital stay (median 6 vs. 7 days, p = 0.011), PCC (11% vs. 14.7%, p = 0.043) and 30-day mortality (0.7% vs. 2.3%, p = 0.018) were lower in the resection and ablation group. Differences faded in multivariable logistic regression due to inclusion of major hepatectomy. ConclusionSignificant hospital variation was observed in the Netherlands. Short-term postoperative outcomes were better after combined resection and ablation, attributed to avoiding complications associated with major hepatectomy.

Ten-Year Outcomes of Percutaneous Radiofrequency Ablation for Colorectal Cancer Liver Metastases in Perivascular vs. Non-Perivascular Locations: A Propensity-Score Matched Study.

PurposeTo compare long-term outcomes of percutaneous radiofrequency ablation for colorectal liver metastases in perivascular versus non-perivascular locations.MethodsThis retrospective study included 388 consecutive patients with colorectal liver metastases (246 men, 142 women; age range 27–86 years) who underwent percutaneous radiofrequency ablation between January 2006 and December 2018. Propensity-score matching was performed for groups with perivascular and non-perivascular colorectal liver metastases. Rates of accumulative local tumor progression, overall survival, intra/extrahepatic recurrence, and complications were compared between the two groups.ResultsWe successfully matched 104 patients each in the perivascular and non-perivascular groups (mean age: 60.1 ± 11.5 and 60.1 ± 11.3 years, respectively). Cumulative local tumor progression rates at 6 months, 1 years, 3 years, and 5 years, respectively, were 8.8%,14.8%, 18.9%, and 18.9% in the perivascular group and 8.8%, 13.1%, 15.5%, and 15.5% in the non-perivascular group. The 1-, 3-, 5-, and 10-year overall survival rates, respectively, were 91.3%, 45.6%, 23.9%, and 18.7% in the perivascular group and 88.0%, 47.2%, 27.2%, and 22.6% in the non-perivascular group. No significant between-group differences were detected in cumulative local tumor progression (p=0.567, hazard ratio: 1.224) or overall survival (p = 0.801, hazard ratio: 1.047). The major complication rate was 1.0% (1/104, p > 0.999) in both groups. Tumor size was the only independent prognostic factor for local tumor progression (hazard ratio: 2.314; p = 0.002). On multivariate analysis for overall colorectal liver metastases, tumor diameter >3 cm, tumor location in the right colon, multiple tumors, and extrahepatic metastases before radiofrequency ablation (hazard ratios: 2.046, 1.920, 1.706, and 1.892, respectively; all p < 0.001) and intrahepatic recurrence (hazard ratio: 1.564; p = 0.002) were associated with poor overall survival.ConclusionCumulative local tumor progression, overall survival, and major complications rates did not differ significantly between perivascular and non-perivascular colorectal liver metastases after percutaneous radiofrequency ablation. For perivascular colorectal liver metastases, percutaneous radiofrequency ablation is a safe and effective treatment option.

Follow-Up 18F-FDG PET/CT versus Contrast-Enhanced CT after Ablation of Liver Metastases of Colorectal Carcinoma-A Cost-Effectiveness Analysis.

Purpose: After a percutaneous ablation of colorectal liver metastases (CRLM), follow-up investigations to evaluate potential tumor recurrence are necessary. The aim of this study was to analyze whether a combined 18F-Fluordesoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) scan is cost-effective compared to a contrast-enhanced computed tomography (CE-CT) scan for detecting local tumor progression. Materials and Methods: A decision model based on Markov simulations that estimated lifetime costs and quality-adjusted life years (QALYs) was developed. Model input parameters were obtained from the recent literature. Deterministic sensitivity analysis of diagnostic parameters based on a Monte-Carlo simulation with 30,000 iterations was performed. The willingness-to-pay (WTP) was set to $100,000/QALY. Results: In the base-case scenario, CE-CT resulted in total costs of $28,625.08 and an efficacy of 0.755 QALYs, whereas 18F-FDG PET/CT resulted in total costs of $29,239.97 with an efficacy of 0.767. Therefore, the corresponding incremental cost-effectiveness ratio (ICER) of 18F-FDG PET/CT was $50,338.96 per QALY indicating cost-effectiveness based on the WTP threshold set above. The results were stable in deterministic and probabilistic sensitivity analyses. Conclusion: Based on our model, 18F-FDG PET/CT can be considered as a cost-effective imaging alternative for follow-up investigations after percutaneous ablation of colorectal liver metastases.

Abstract 6519: Patient, primary colorectal tumor and liver metastases factors which influence survival after liver metastasectomy and therefore should be considered at the preoperative tumor board

Abstract Aim of the study: Patients with colorectal liver metastases (CRLM) should be considered for liver surgery and this study illuminate important factors to be considered at the preoperative multidisciplinary tumor board. Background: Survival after surgical resection or ablation of colorectal liver metastases is increasingly favorable but only a minority of patients undergo curatively intended treatment. Several studies have shown the importance of assessing resectability by liver surgeons. Which prognostic factors to consider before liver surgery is not fully understood. Methods: The Swedish colorectal cancer registry (SCRCR) and the Swedish registry for liver tumors (SweLiv) were linked to identify radically resected primary colorectal cancer patients during the years 2009-2013 also surgically treated for liver metastases, synchronously or metachronously. CRLM characteristics and treatment strategies as well as primary tumor and patient factors were analyzed for prognostic impact. 5-year age-standardized relative survival (RS) and 5-year excess mortality rate ratio (EMRR) were calculated. Treatment with ablation only for tumors with maximum size of 30 mm was analyzed in a propensity score weighted cox regression. Results: 1325 patients were included in the study cohort, whereof 300 were 75 years or older. 1200 were treated with resection and 125 were treated with ablation only. Age-standardized relative five-year survival after open resection of colorectal liver metastases was 54.8 % (95 % CI: 50.6-58.7) and after ablation 32.4 % (95 % CI: 23.3-41.9). Multivariate analysis identified age ≥75 years, tumor size &amp;gt;20 mm, location in segment 4, 6, 7 or 8, multiple metastatic sites and progress after chemotherapy as important risk factors with more than 25 % higher EMRR. Only when analyzed without segments included in the multivariate model was the number of metastases a significant risk factor. Vascular invasion, lymph node ratio and complications at time of primary tumor resection were also important negative prognostic factors. Ablation of small metastases compared to resection was a significant risk factor (HR 2.25 (95 % CI 1.61-3.15)). Conclusion: Tumor size over 20 mm and location of metastases as well as lymph node status and complications after resection of the primary tumor are important risk factors for survival outcome after liver surgery of CRLM. Progress after preoperative chemotherapy and ablation compared to resection more than doubled the risk of death within 5 years. Citation Format: Peter Scherman, Peter Naredi, Ingvar Syk, Erik Holmberg, Magnus Rizell. Patient, primary colorectal tumor and liver metastases factors which influence survival after liver metastasectomy and therefore should be considered at the preoperative tumor board [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6519.

Neoplastic Seeding in Abdominal Wall Following Radiofrequency Ablation of Colorectal Liver Metastasis: Case Report

Colorectal liver metastasis (CRLM) is the most common lesion diagnosed in the liver worldwide and new therapies have been proposed over the last decades. On the leading edge of these therapies, radiofrequency ablation (RFA) has been increasingly applied for treatment these lesions. The procedure can be done by percutaneous approach guided by CT, or during open or laparoscopic surgery. Although findings in preliminary reports suggest that this procedure is both safe and effective, only a few studies have been published. We present a 69-year-old female, previously submitted to two hepatic resections and one RFA for treatment of CRLM, who developed an abdominal wall recurrence due to neoplastic seeding after RFA procedure. In the published literature thus far, some risk factors have been associated with neoplastic seeding following RFA, like subcapsular location, multiple electrode placements, multiple RFA treatments and poor tumor differentiation grade. Technical features like access through normal liver substance and tract needle ablation may play a role in mitigating the risk of this complication. Although it seems to be a safe procedure, only a few retrospective papers have been published its rare complications and outcomes. Nevertheless, patients with localized disease may benefit from surgical resection.

Long-term results of percutaneous microwave ablation for colorectal liver metastases

BackgroundRadiofrequency ablation (RFA) has been used for therapy of colorectal liver metastases (CRLMs) several years, with considerable data confirming its safety and efficacy. However, there are few studies focusing on the long-term results of percrtaneous microwave ablation (PMWA) for CRLMs. The aim of this study was to evaluate the long-term survival and prognostic factors in patients with CRLMs undergoing PMWA. MethodsWe retrospectively analyzed treatment and survival parameters of 210 patients with CRLMs who had received PMWA in a single center from January 2010 to December 2017. Prognostic factors for survival were evaluated by means of univariate and multivariate analyses. ResultsThe median follow-up time after PMWA was 48 months. The median overall survival (OS) time were 40.0 months (95% CI, 31.4 to 48.5 months), with 1-, 2, 3-, 4, and 5-year cumulative survival rates of 98.6%, 73.3%, 53.3%, 42.2%, and 32.9%, respectively. Tumor number (P = 0.004; HR: 1.838; CI: 1.213– 2.784), main tumor size (P = 0.017; HR: 1.631; CI: 1.093– 2.436), and serum CEA level (P = 0.032; HR: 1.559; CI: 1.039–2.340) were found as independent predictors of OS. The median OS time for patients with resectable lesions was 60.91 months (95% CI, 51.36 to 70.47 months), with 5-year cumulative survival rates of 53.5%. ConclusionPMWA is a safe and effective treatment for CRLMs, with a favorable long-term outcome. Multiple lesions, main tumor diameter>3 cm, and serum CEA >30 ng/ml have a significant negative effect on OS.

Image-Guided Thermal Ablation for Colorectal Liver Metastases

Image-guided percutaneous thermal ablation is a widely acceptable local therapy for patients with colorectal liver metastases who are noneligible for surgery or present with recurrence after hepatectomy. The increasing knowledge of factors that affect oncologic outcomes has allowed selected patients with resectable small volume colorectal liver metastases to be treated by thermal ablation with curative intent. The continuous technological evolutions in imaging and image-guidance and the wide implementation of microwave ablation that overcomes most of the limitations of radiofrequency ablation have contributed to this paradigm shift. The importance of patient selection, ablation margin evaluation, and confirmation of complete tumor ablation (A0) are discussed in this article.

Laparoscopic Versus Open Thermal Ablation of Colorectal Liver Metastases: A Propensity Score-Based Analysis of Local Control of the Ablated Tumors.

Laparoscopic ablation (LA) of colorectal liver metastases (CRLMs) is frequently performed in combination with laparoscopic liver resection or as a stand-alone procedure. However, LA is technically demanding and whether the results are comparable with those of open ablation (OA) has not been determined to date. This study compared the effectiveness of LA and OA in achieving local tumor control of CRLMs. Patients undergoing LA or OA of CRLMs at Ghent University Hospital between June 2007 and February 2018 were identified from a prospective database. Lesions treated by LA and OA were matched 1:1 using a propensity score based on lesions (liver segment, size, deepness, proximity to a vessel), patients, and procedural characteristics. Ablation sites were followed up with computed-tomography or magnetic resonance imaging to assess the completeness of the ablation and ablation-site recurrence (ASR). Analysis of ASR was performed with the Kaplan-Meier method and Cox regression. In this study, 163 patients underwent the surgical ablation (78 LA, 85 OA) of 333 CRLMs (143 LA, 190 OA). After matching, 220 lesions (110 LA, 110 OA) were analyzed. Ablation was complete in 93.7% (LA) and 97.3% (OA) of the sites (p = 0.195). No difference in ASR was observed (p = 0.351), with a cumulative risk of ASR at 12months of 9.1% (LA) and 8.2% (OA). After multivariable analysis, ASR was confirmed to be independent of the surgical approach. The findings showed that LA and OA achieve a comparable local control of CRLMs. This result further supports the adoption of a laparoscopic approach for the treatment of CRLMs.

Hepatic arterial infusion chemotherapy for colorectal liver metastases revisited

BackgroundRecent reports indicate improved survival in patients undergoing surgical treatment for colorectal liver metastases (CRLM) with hepatic arterial infusion (HAI) pump chemotherapy compared to surgery alone. MethodsPatients who underwent resection and/or ablation of CRLM between 1996 and 2016 were included from a single-institution prospectively maintained database. Proportional hazards regression analysis was performed to determine predictors of overall survival (OS) and 3:1 propensity score analysis (PSA). ResultsOf 349 patients included, 36 had HAI pumps placed (HAI group) and 313 did not (no-HAI group). There was no difference in primary tumor grade (p = 0.24), ECOG status (p = 0.44), tumor number (p = 0.1), tumor size (p = 0.56), margin status (p = 0.76) between the two groups.Median overall survival was 44.7months vs 37.1months for the HAI versus no-HAI group (p = 0.01). Cox proportional hazards regression analysis demonstrated positive margin status (HR:2.47,p < 0.0001), HAI therapy (HR:0.56,p = 0.02), preoperative chemotherapy (HR:0.69,p = 0.02) and tumor diameter (HR:1.07,p = 0.005) as predictors of OS. In 3:1 PSA, 32 HAI subjects were matched with 87 non-HAI subjects balancing all covariates. Median OS was 42.4 months versus 35.6 months for the HAI versus no-HAI group (p = 0.03). ConclusionSurgical treatment of CRLM combined with HAI chemotherapy is associated with improved OS compared to surgery alone. Further study of this treatment approach is indicated.

Predictors of survival after surgical ablation of colorectal liver metastases

Background: Local ablative therapy to treat colorectal liver metastases (CRLM) is shifting from palliative to curative intent, despite hard evidence to support its beneficial impact in curable patients. The aim of this monocentric retrospective cohort study was to analyze clinical and oncological outcomes after surgical ablation (SA) of CRLM, and to determine predictors of survival. Conclusions: Between 2003-2015 SA was performed in 321 consecutive patients (F/M ratio 121/200; median (range) age 63 (18-87) years) to treat 649 CRLM. SA was done via laparoscopy in 239 (74%), and combined with simultaneous colorectal and/or liver resection in 113 (36%) patients. Systemic chemotherapy was given in 206 (64%) before and in 179 (56%) patients after surgery. The impact of 14 prognostic factors on survival was evaluated using univariable and multivariable Cox regression models. Patients were followed up until death or until the date of study closure on November 2017, with a median follow-up time of 38 (0–158) months. Results: Postoperative complications occurred in 71 (22%) patients. Severe complications (TOSGS grade >3a) were observed in 26 (8%) patients, including 1 (0.3%) non-procedure related death. Median (95% CI) OS time was 52 (47–64) months and DFS 9.4 (8.3-10.5) months. OS and DFS rates at 5 and 10 years after surgery were 45.2% and 27.8%, and 14.4% and 13.7%, respectively. Independent predictors with negative influence on OS were the occurrence of de-novo CRLM (HR 3.631, CI 2.306-5.976, p<0.001), pre-operative chemotherapy (HR 1.960, CI 1.282-3.065, p=0.002), age >63y (HR 1.635, CI 1.144-2.352, p=0.007), and the presence of lymph node metastasis (pN) of colorectal cancer primary (HR 1.646, CI 1.095-2.546, p=0.016). Conclusion: Surgical ablation of CRLM provides survival rates similar to surgical resection. The occurrence of de-novo liver metastases is the predominant predictor of overall survival.

Resection versus ablation for colorectal liver metastases in the 21st century: A systematic review of the literature

Resection versus ablation for colorectal liver metastases in the 21st century: A systematic review of the literature

Recurrence patterns following laparscopic ultrasound-guided microwave ablation for colorectal liver metastases

Recurrence patterns following laparscopic ultrasound-guided microwave ablation for colorectal liver metastases

Adjuvant Hepatic Arterial Infusion Pump Chemotherapy After Resection of Colorectal Liver Metastases: Results of a Safety and Feasibility Study in The Netherlands

BackgroundThe 10-year overall survival with adjuvant hepatic arterial infusion pump (HAIP) chemotherapy after resection of colorectal liver metastases (CRLMs) was 61% in clinical trials from Memorial Sloan Kettering Cancer Center. A pilot study was performed to evaluate the safety and feasibility of adjuvant HAIP chemotherapy in patients with resectable CRLMs.Study DesignA phase II study was performed in two centers in The Netherlands. Patients with resectable CRLM without extrahepatic disease were eligible. All patients underwent complete resection and/or ablation of CRLMs and pump implantation. Safety was determined by the 90-day HAIP-related postoperative complications from the day of pump placement (Clavien–Dindo classification, grade III or higher) and feasibility by the successful administration of the first cycle of HAIP chemotherapy.ResultsA total of 20 patients, with a median age of 57 years (interquartile range [IQR] 51–64) were included. Grade III or higher HAIP-related postoperative complications were found in two patients (10%), both of whom had a reoperation (without laparotomy) to replace a pump with a slow flow rate or to reposition a flipped pump. No arterial bleeding, arterial dissection, arterial thrombosis, extrahepatic perfusion, pump pocket hematoma, or pump pocket infections were found within 90 days after surgery. After a median of 43 days (IQR 29–52) following surgery, all patients received the first dose of HAIP chemotherapy, which was completed uneventfully in all patients.ConclusionPump implantation is safe, and administration of HAIP chemotherapy is feasible, in patients with resectable CRLMs, after training of a dedicated multidisciplinary team.

Radiofrequency ablation of colorectal liver metastases

Radical liver resection is the only method for the treatment of patients with colorectal liver metastases (CLM); however, only 20-30% of patients with CLMs can be radically treated. Radiofrequency ablation (RFA) is one of the possible methods of palliative treatment in such patients. RFA was performed in 381 patients with CLMs between 01 Jan 2001 and 31 Dec 2018. The mean age of the patients was 65.2±8.7 years. The male to female ratio was 2:1. Open laparotomy was done in 238 (62.5%) patients and the CT-navigated transcutaneous approach was used in 143 (37.5%) patients. CLMs.

Peri-tumoral Metallic Implants Reduce the Efficacy of Irreversible Electroporation for the Ablation of Colorectal Liver Metastases

To evaluate the effect of peri-tumoral metallic implants (MI) on the safety and efficacy of percutaneous irreversible electroporation (IRE) of colorectal liver metastasis (CRLM). In this retrospective study, 25 patients (12 women, 13 men; MI: 13, no MI: 12) were treated for 29 CRLM. Patient characteristics, tumor location and size, treatment parameters and the presence of MI were evaluated as determinants of local tumor progression (LTP) with the competing risks model (univariate and multivariate analyses). Patient-specific computer models were created to examine the effect of the MI on the electric field used to induce IRE, probability of cell kill and potential thermal effects. Patients had a median follow-up of 25months, during which no IRE-related major complications were reported. Univariate analysis showed that tumor size (> 2cm), probe spacing (> 20mm) and the presence of MI (p < 0.05) were significant predictors of time to LTP, but only the latter was found to be an independent predictor on multivariate analysis (sub-hazard ratio = 6.5; [95% CI 1.99, 21.4]; p = 0.002). The absence of peri-tumoral MI was associated with higher progression-free survival at 12months (92.3% [56.6, 98.9] vs 12.5% [2.1, 32.8]). Computer simulations indicated significant distortions and reduction in electric field strength near MI, which could have contributed to under-treatment of the tumor. Peri-tumoral MI increases the risk of treatment failure following IRE of CRLM.