Colorectal liver metastases: surgery versus thermal ablation (COLLISION) - a phase III single-blind prospective randomized controlled trial.

BACKGROUND: Radiofrequency ablation (RFA) and microwave ablation (MWA) are widely accepted techniques to eliminate small unresectable colorectal liver metastases (CRLM). Although previous studies labelled thermal ablation inferior to surgical resection, the apparent selection bias when comparing patients with unresectable disease to surgical candidates, the superior safety profile, and the competitive overall survival results for the more recent reports mandate the setup of a randomized controlled trial. The objective of the COLLISION trial is to prove non-inferiority of thermal ablation compared to hepatic resection in patients with at least one resectable and ablatable CRLM and no extrahepatic disease. METHODS: In this two-arm, single-blind multi-center phase-III clinical trial, six hundred and eighteen patients with at least one CRLM (≤3 cm) will be included to undergo either surgical resection or thermal ablation of appointed target lesion(s) (≤3 cm). Primary endpoint is OS (overall survival, intention-to-treat analysis). Main secondary endpoints are overall disease-free survival (DFS), time to progression (TTP), time to local progression (TTLP), primary and assisted technique efficacy (PTE, ATE), procedural morbidity and mortality, length of hospital stay, assessment of pain and quality of life (QoL), cost-effectiveness ratio (ICER) and quality-adjusted life years (QALY). DISCUSSION: If thermal ablation proves to be non-inferior in treating lesions ≤3 cm, a switch in treatment-method may lead to a reduction of the post-procedural morbidity and mortality, length of hospital stay and incremental costs without compromising oncological outcome for patients with CRLM. TRIAL REGISTRATION: NCT03088150 , January 11th 2017.

Radiofrequency and Microwave Ablation Compared to Systemic Chemotherapy and to Partial Hepatectomy in the Treatment of Colorectal Liver Metastases: A Systematic Review and Meta-Analysis.

PURPOSE: To assess safety and outcome of radiofrequency ablation (RFA) and microwave ablation (MWA) as compared to systemic chemotherapy and partial hepatectomy (PH) in the treatment of colorectal liver metastases (CRLM). METHODS: MEDLINE, Embase and the Cochrane Library were searched. Randomized trials and comparative observational studies with multivariate analysis and/or matching were included. Guidelines from National Guideline Clearinghouse and Guidelines International Network were assessed using the AGREE II instrument. RESULTS: The search revealed 3530 records; 328 were selected for full-text review; 48 were included: 8 systematic reviews, 2 randomized studies, 26 comparative observational studies, 2 guideline-articles and 10 case series; in addition 13 guidelines were evaluated. Literature to assess the effectiveness of ablation was limited. RFA + systemic chemotherapy was superior to chemotherapy alone. PH was superior to RFA alone but not to RFA + PH or to MWA. Compared to PH, RFA showed fewer complications, MWA did not. Outcomes were subject to residual confounding since ablation was only employed for unresectable disease. CONCLUSION: The results from the EORTC-CLOCC trial, the comparable survival for ablation + PH versus PH alone, the potential to induce long-term disease control and the low complication rate argue in favour of ablation over chemotherapy alone. Further randomized comparisons of ablation to current-day chemotherapy alone should therefore be considered unethical. Hence, the highest achievable level of evidence for unresectable CRLM seems reached. The apparent selection bias from previous studies and the superior safety profile mandate the setup of randomized controlled trials comparing ablation to surgery.

Percutaneous Liver Tumour Ablation: Image Guidance, Endpoint Assessment, and Quality Control.

Liver tumour ablation nowadays represents a routine treatment option for patients with primary and secondary liver tumours. Radiofrequency ablation and microwave ablation are the most widely adopted methods, although novel techniques, such as irreversible electroporation, are quickly working their way up. The percutaneous approach is rapidly gaining popularity because of its minimally invasive character, low complication rate, good efficacy rate, and repeatability. However, matched to partial hepatectomy and open ablations, the issue of ablation site recurrences remains unresolved and necessitates further improvement. For percutaneous liver tumour ablation, several real-time imaging modalities are available to improve tumour visibility, detect surrounding critical structures, guide applicators, monitor treatment effect, and, if necessary, adapt or repeat energy delivery. Known predictors for success are tumour size, location, lesion conspicuity, tumour-free margin, and operator experience. The implementation of reliable endpoints to assess treatment efficacy allows for completion-procedures, either within the same session or within a couple of weeks after the procedure. Although the effect on overall survival may be trivial, (local) progression-free survival will indisputably improve with the implementation of reliable endpoints. This article reviews the available needle navigation techniques, evaluates potential treatment endpoints, and proposes an algorithm for quality control after the procedure.

RF Ablation of Giant Hemangiomas Inducing Acute Renal Failure: A Report of Two Cases.

OBJECTIVE: In patients that require treatment for hepatic giant cavernous hemangiomas (GCH), radiofrequency ablation (RFA) has been suggested to represent a safe and effective alternative to invasive surgery. In a recent report of bipolar RFA, using two expandable needle electrodes, was uneventfully performed in patients with large GCH (>10 cm). The objective of this report is to present two cases in which bipolar RFA of symptomatic GCH was complicated by acute kidney injury. MATERIALS AND METHODS: In 2015 we treated two patients for very large symptomatic GCH (15.7 and 25.0 cm) with bipolar RFA during open laparotomy. RESULTS: In both patients the urine showed a red-brown discoloration directly after the ablation. They became anuric and presented with progressive dyspnea, tachypnea, and tachycardia, requiring hemodialysis for a period of 1 month in one case. Lab results revealed hemepigment-induced acute kidney. Both patients fully recovered and both showed a complete relief of symptoms at 3 months following the procedure. CONCLUSION: RFA for large GCHs can cause hemepigment-induced acute kidney injury due to massive intravascular hemolysis. The presented cases suggest that caution is warranted and advocate an upper limit regarding the volume of GCHs that can be safely ablated.

MWA Versus RFA for Perivascular and Peribiliary CRLM: A Retrospective Patient- and Lesion-Based Analysis of Two Historical Cohorts.

PURPOSE: To retrospectively analyse the safety and efficacy of radiofrequency ablation (RFA) versus microwave ablation (MWA) in the treatment of unresectable colorectal liver metastases (CRLM) in proximity to large vessels and/or major bile ducts. METHOD AND MATERIALS: A database search was performed to include patients with unresectable histologically proven and/or (18)F-FDG-PET avid CRLM who were treated with RFA or MWA between January 2001 and September 2014 in a single centre. All lesions that were considered to have a peribiliary and/or perivascular location were included. Univariate logistic regression analysis was performed to assess the distribution of patient, tumour and procedure characteristics. Multivariate logistic regression was used to correct for potential confounders. RESULTS: Two hundred and forty-three patients with 774 unresectable CRLM were ablated. One hundred and twenty-two patients (78 males; 44 females) had at least one perivascular or peribiliary lesion (n = 199). Primary efficacy rate of RFA was superior to MWA after 3 and 12 months of follow-up (P = 0.010 and P = 0.022); however, after multivariate analysis this difference was non-significant at 12 months (P = 0.078) and vanished after repeat ablations (P = 0.39). More CTCAE grade III complications occurred after MWA versus RFA (18.8 vs. 7.9 %; P = 0.094); biliary complications were especially common after peribiliary MWA (P = 0.002). CONCLUSION: For perivascular CRLM, RFA and MWA are both safe treatment options that appear equally effective. For peribiliary CRLM, MWA has a higher complication rate than RFA, with similar efficacy. Based on these results, it is advised to use RFA for lesions in the proximity of major bile ducts.

Radiofrequency Ablation to Improve Survival After Conversion Chemotherapy for Colorectal Liver Metastases.

INTRODUCTION: Systemic chemotherapy is able to convert colorectal liver metastases (CRLM) that are initially unsuitable for local treatment into locally treatable disease. Surgical resection further improves survival in these patients. Our aim was to evaluate disease-free survival (DFS), overall survival, and morbidity for patients with CRLM treated with RFA following effective downstaging by chemotherapy, and to identify factors associated with recurrence and survival. MATERIALS AND METHODS: Included patients had liver-dominant CRLM initially unsuitable for local treatment but eligible for RFA or RFA with resection after downstaging by systemic chemotherapy. Chemotherapeutic regimens consisted predominantly of CapOx, with or without bevacizumab. Follow-up was conducted with PET-CT or thoraco-pelvic CT. RESULTS: Fifty-one patients had a total of 325 CRLM (median = 7). Following chemotherapy, 183 lesions were still visible on CT (median = 3). Twenty-six patients were treated with RFA combined with resection. During surgery, 309 CRLM were retrieved on intraoperative ultrasound (median = 5). Median survival was 49 months and was associated with extrahepatic disease at time of presentation and recurrences after treatment. Estimated cumulative survival at 1, 3 and 4 years was 90, 63 and 45 %, respectively. Median DFS was 6 months. Twelve patients remained free of recurrence after a mean follow-up of 32.6 months. CONCLUSION: RFA of CRLM after conversion chemotherapy provides potential local control and a good overall survival. To prevent undertreatment, the involvement of a multidisciplinary team in follow-up imaging and assessment of local treatment possibilities after palliative chemotherapy for liver-dominant CRLM should always be considered.

Colorectal liver metastatic disease: efficacy of irreversible electroporation--a single-arm phase II clinical trial (COLDFIRE-2 trial).

BACKGROUND: Irreversible electroporation (IRE) is a novel image-guided tumor ablation technique that has shown promise for the ablation of lesions in proximity to vital structures such as blood vessels and bile ducts. The primary aim of the COLDFIRE-2 trial is to investigate the efficacy of IRE for unresectable, centrally located colorectal liver metastases (CRLM). Secondary outcomes are safety, technical success, and the accuracy of contrast-enhanced (ce)CT and (18)F-FDG PET-CT in the detection of local tumor progression (LTP). METHODS/DESIGN: In this single-arm, multicenter phase II clinical trial, twenty-nine patients with (18)F-FDG PET-avid CRLM ≤ 3,5 cm will be prospectively included to undergo IRE of the respective lesion. All lesions must be unresectable and unsuitable for thermal ablation due to vicinity of vital structures. Technical success is based on ceMRI one day post-IRE. All complications related to the IRE procedure are registered. Follow-up consists of (18)F-FDG PET-CT and 4-phase liver CT at 3-monthly intervals during the first year of follow-up. Treatment efficacy is defined as the percentage of tumors successfully eradicated 12 months after the initial IRE procedure based on clinical follow-up using both imaging modalities, tumor marker and (if available) histopathology. To determine the accuracy of (18)F-FDG PET-CT and ceCT, both imaging modalities will be individually scored by two reviewers that are blinded for the final oncologic outcome. DISCUSSION: To date, patients with a central CRLM unsuitable for resection or thermal ablation have no curative treatment option and are given palliative chemotherapy. For these patients, IRE may prove a life-saving treatment option. The results of the proposed trial may represent an important step towards the implementation of IRE for central liver tumors in the clinical setting. TRIAL REGISTRATION NUMBER: NCT02082782.

Irreversible Electroporation for Colorectal Liver Metastases.

Image-guided tumor ablation techniques have significantly broadened the treatment possibilities for primary and secondary hepatic malignancies. A new ablation technique, irreversible electroporation (IRE), was recently added to the treatment armamentarium. As opposed to thermal ablation, cell death with IRE is primarily induced using electrical energy: electrical pulses disrupt the cellular membrane integrity, resulting in cell death while sparing the extracellular matrix of sensitive structures such as the bile ducts, blood vessels, and bowel wall. The preservation of these structures makes IRE attractive for colorectal liver metastases (CRLM) that are unsuitable for resection and thermal ablation owing to their anatomical location. This review discusses different technical and practical issues of IRE for CRLM: the indications, patient preparations, procedural steps, and different "tricks of the trade" used to improve safety and efficacy of IRE. Imaging characteristics and early efficacy results are presented. Much is still unknown about the exact mechanism of cell death and about factors playing a crucial role in the extent of cell death. At this time, IRE for CRLM should only be reserved for small tumors that are truly unsuitable for resection or thermal ablation because of abutment of the portal triad or the venous pedicles.

Transcatheter CT hepatic arteriography-guided percutaneous ablation to treat ablation site recurrences of colorectal liver metastases: the incomplete ring sign.

Transcatheter computed tomography (CT) arterial portography-guided percutaneous liver tumor ablation has been proved to be feasible and accurate in treating liver metastases from colorectal origin that are obscure on ultrasound and unenhanced CT. However, distinguishing local recurrence from scars after ablation can still be difficult. This report describes nine patients with recurrences after ablation in whom transcatheter CT hepatic arteriography allowed differentiation of recurring and residual tumor tissue (incomplete ring enhancing lesion) from tumor-free nonenhancing scars. Using CT hepatic arteriography, it is possible to plan and guide percutaneous retreatment and confirm technical success without performing oversized repeat ablations or jeopardizing patients renal function.

Percutaneous irreversible electroporation of locally advanced pancreatic carcinoma using the dorsal approach: a case report.

Irreversible electroporation (IRE) is a novel image-guided ablation technique that is increasingly used to treat locally advanced pancreatic carcinoma (LAPC). We describe a 67-year-old male patient with a 5 cm stage III pancreatic tumor who was referred for IRE. Because the ventral approach for electrode placement was considered dangerous due to vicinity of the tumor to collateral vessels and duodenum, the dorsal approach was chosen. Under CT-guidance, six electrodes were advanced in the tumor, approaching paravertebrally alongside the aorta and inferior vena cava. Ablation was performed without complications. This case describes that when ventral electrode placement for pancreatic IRE is impaired, the dorsal approach could be considered alternatively.

Percutaneous Irreversible Electroporation of a Large Centrally Located Hepatocellular Adenoma in a Woman with a Pregnancy Wish.

Irreversible electroporation (IRE) is a novel image-guided ablation technique that is rapidly gaining popularity in the treatment of malignant liver tumors located near large vessels or bile ducts. We describe a 28-year-old female patient with a 5 cm large, centrally located hepatocellular adenoma who wished to get pregnant. Regarding the risk of growth and rupture of the adenoma caused by hormonal changes during pregnancy, treatment of the tumor was advised prior to pregnancy. However, due to its central location, the tumor was considered unsuitable for resection and thermal ablation. Percutaneous CT-guided IRE was performed without complications and led to rapid and impressive tumor shrinkage. Subsequent pregnancy and delivery went uncomplicated. This case report suggests that the indication for IRE may extend to the treatment of benign liver tumors that cannot be treated safely otherwise.

The use of PET-MRI in the follow-up after radiofrequency- and microwave ablation of colorectal liver metastases.

BACKGROUND: Thermal ablation of colorectal liver metastases (CRLM) may result in local progression, which generally appear within a year of treatment. As the timely diagnosis of this progression allows potentially curative local treatment, an optimal follow-up imaging strategy is essential. PET-MRI is a one potential imaging modality, combining the advantages of PET and MRI. The aim of this study is evaluate fluorine-18 deoxyglucose positron emission tomography (FDG) PET-MRI as a modality for detection of local tumor progression during the first year following thermal ablation, as compared to the current standard, FDG PET-CT. The ability of FDG PET-MRI to detect new intrahepatic lesions, and the extent to which FDG PET-MRI alters clinical management, inter-observer variability and patient preference will also be included as secondary outcomes. METHODS/DESIGN: Twenty patients undergoing treatment with radiofrequency or microwave ablation for (recurrent) CRLM will be included in this prospective trial. During the first year of follow-up, patients will be scanned at the VU University Medical Center at 3-monthly intervals using a 4-phase liver CT, FDG PET-CT and FDG PET-MRI. Patients treated with chemotherapy <6 weeks prior to scanning or with a contra-indication for MRI will be excluded. MRI will be performed using both whole body imaging (mDixon) and dedicated liver sequences, including diffusion-weighted imaging, T1 in-phase and opposed-phase, T2 and dynamic contrast-enhanced imaging. The results of all modalities will be scored by 4 individual reviewers and inter-observer agreement will be determined. The reference standard will be histology or clinical follow-up. A questionnaire regarding patients' experience with both modalities will also be completed at the end of the follow-up year. DISCUSSION: Improved treatment options for local site recurrences following CRLM ablation mean that accurate post-ablation staging is becoming increasingly important. The combination of the sensitivity of MRI as a detection method for small intrahepatic lesions with the ability of FDG PET to visualize enhanced metabolism at the ablation site suggests that FDG PET-MRI could potentially improve the accuracy of (early) detection of progressive disease, and thus allow swifter and more effective decision-making regarding appropriate treatment. TRIAL REGISTRATION NUMBER: NCT01895673.

Transcatheter CT arterial portography and CT hepatic arteriography for liver tumor visualization during percutaneous ablation.

PURPOSE: To evaluate the feasibility of combining transcatheter computed tomography (CT) arterial portography or transcatheter CT hepatic arteriography with percutaneous liver ablation for optimized and repeated tumor exposure. MATERIALS AND METHODS: Study participants were 20 patients (13 men and 7 women; mean age, 59.4 y; range, 40-76 y) with unresectable liver-only malignancies--14 with colorectal liver metastases (29 lesions), 5 with hepatocellular carcinoma (7 lesions), and 1 with intrahepatic cholangiocarcinoma (2 lesions)--that were obscure on nonenhanced CT. A catheter was placed within the superior mesenteric artery (CT arterial portography) or in the hepatic artery (CT hepatic arteriography). CT arterial portography or CT hepatic arteriography was repeatedly performed after injecting 30-60 mL 1:2 diluted contrast material to plan, guide, and evaluate ablation. The operator confidence levels and the liver-to-lesion attenuation differences were assessed as well as needle-to-target mismatch distance, technical success, and technique effectiveness after 3 months. RESULTS: Technical success rate was 100%; there were no major complications. Compared with conventional unenhanced CT, operator confidence increased significantly for CT arterial portography or CT hepatic arteriography cases (P < .001). The liver-to-lesion attenuation differences between unenhanced CT, contrast-enhanced CT, and CT arterial portography or CT hepatic arteriography were statistically significant (mean attenuation difference, 5 HU vs 28 HU vs 70 HU; P < .001). Mean needle-to-target mismatch distance was 2.4 mm ± 1.2 (range, 0-12.0 mm). Primary technique effectiveness at 3 months was 87% (33 of 38 lesions). CONCLUSIONS: In patients with technically unresectable liver-only malignancies, single-session CT arterial portography-guided or CT hepatic arteriography-guided percutaneous tumor ablation enables repeated contrast-enhanced imaging and real-time contrast-enhanced CT fluoroscopy and improves lesion conspicuity.

Irreversible electroporation for nonthermal tumor ablation in the clinical setting: a systematic review of safety and efficacy.

PURPOSE: To provide an overview of current clinical results of irreversible electroporation (IRE), a novel, nonthermal tumor ablation technique that uses electric pulses to induce cell death, while preserving structural integrity of bile ducts and vessels. METHODS: All in-human literature on IRE reporting safety or efficacy or both was included. All adverse events were recorded. Tumor response on follow-up imaging from 3 months onward was evaluated. RESULTS: In 16 studies, 221 patients had 325 tumors treated in liver (n = 129), pancreas (n = 69), kidney (n = 14), lung (n = 6), lesser pelvis (n = 1), and lymph node (n = 2). No major adverse events during IRE were reported. IRE caused only minor complications in the liver; however, three major complications were reported in the pancreas (bile leak [n = 2], portal vein thrombosis [n = 1]). Complete response at 3 months was 67%-100% for hepatic tumors (93%-100% for tumors o 3 cm). Pancreatic IRE combined with surgery led to prolonged survival compared with control patients (20 mo vs 13 mo) and significant pain reduction. CONCLUSIONS: In cases where other techniques are unsuitable, IRE is a promising modality for the ablation of tumors near bile ducts and blood vessels. This articles gives an extensive overview of the available evidence, which is limited in terms of quality and quantity. With the limitations of the evidence in mind, IRE of central liver tumors seems relatively safe without major complications, whereas complications after pancreatic IRE appear more severe. The available limited results for tumor control are generally good. Overall, the future of IRE for difficult-to-reach tumors appears promising.

[Irreversible electroporation: a new form of image-guided tumour ablation]. / Irreversibele elektroporatie: een nieuwe vorm van beeldgestuurde tumorablatie.

Irreversible electroporation (IRE) is a new, non-thermal image-guided tumour ablation technique. The repeated application of high-voltage electrical pulses causes pores to form in the cell membrane, so that cells lose their homeostatic properties, and die. The advantage of IRE over other local ablation techniques is that IRE selectively destroys cells, whilst the surrounding extracellular matrix structures remain intact. Therefore, the anatomic framework that gives vulnerable structures such as bile ducts, blood vessels, ureters and nerves their shape and strength is preserved during IRE, which allows for safe ablation of tumours near these vulnerable structures. Both in the Netherlands and worldwide, various clinical studies are being run on the safety and efficacy of IRE for centrally located hepatic and pancreatic tumours, which are unsuitable for the current local therapies (surgical resection, irradiation or thermal ablation) due to their anatomic location. Although the long-term results are as yet unknown, the future of IRE appears promising. IRE may prove a valuable tool to add in the multidisciplinary treatment of cancer.

PET-CT after radiofrequency ablation of colorectal liver metastases: suggestions for timing and image interpretation.

INTRODUCTION: The main area of concern regarding radiofrequency ablation (RFA) of colorectal liver metastases is the risk of developing a local site recurrence (LSR). Reported accuracy of PET-CT in detecting LSR is high compared to morphological imaging alone, but no internationally accepted criteria for image interpretation have been defined. Our aim was to assess criteria for FDG PET-CT image interpretation following RFA, and to define a timetable for follow-up detection of LSR. METHODS: Patients who underwent RFA for colorectal liver metastases between 2005 and 2011, with FDG-PET follow-up within one year after treatment were included. Results of repeat FDG-PET scans were evaluated until a LSR was diagnosed. Results. One hundred-seventy scans were obtained for 79 patients (179 lesions), 57 scans (72%) were obtained within 6 months of treatment. Thirty patients developed local recurrence; 29 (97%) within 1 year. Only 2% of lesions of <1cm and 4% of <2 cm showed a LSR. CONCLUSION: The majority of local site recurrences are diagnosed within one year after RFA. Regular follow-up using FDG PET-CT within this period is advised, so repeated treatment can be initiated. Rim-shaped uptake may be present until 4-6 months, complicating evaluation. The benefit in the follow-up of lesions <2 cm may be limited.

Incidence and treatment of local site recurrences following RFA of colorectal liver metastases.

BACKGROUND: Patients with colorectal liver metastases (CRLM) who are ineligible for curative surgery are potential candidates for radiofrequency ablation (RFA). Although RFA has emerged as a well accepted and documented treatment modality, there are still some reservations because of initially high rates of local site recurrences (LSR). The aim of the present study was to evaluate LSR levels following RFA treatment, with a specific focus on re-treatment and survival. PATIENTS AND METHODS: All patients ineligible for curative resection of CRLM and undergoing RFA alone or in combination with resection were prospectively included from July 2000 to December 2010 and retrospectively analyzed. Patients with untreatable extrahepatic disease were excluded. FDG PET-CT was conducted at 3-6 month intervals after RFA. Patients with LSR were evaluated for re-treatment. RESULTS: A total of 132 patients were treated with RFA, which was combined with resection in 64 patients. A total of 290 lesions were ablated, with a mean number of 2.19 per patient and a mean size of 2.2 cm. Median survival was 41 months, with a 3- and 5-year survival of, respectively, 60 and 30.8 %. Following initial RFA, 39 patients developed an LSR in 40 ablated lesions, and local recurrence was strongly related to lesion size. Re-treatment could be performed in 26/39 patients, of whom eight remained disease-free. CONCLUSIONS: Radiofrequency ablation can be applied to CRLM of less than 3 cm with curative intent. In the absence of extensive intrahepatic or extrahepatic disease, renewed treatment of local recurrences should be considered and is often successful.

Radiofrequency ablation of large size liver tumours using novel plan-parallel expandable bipolar electrodes: initial clinical experience.

PURPOSE: Although radiofrequency ablation (RFA) is a promising method for local treatment of liver malignancies, with conventional monopolar systems recurrence rates for large size tumours (≥3.5 cm) remain high. The objective of this study was to evaluate the safety, feasibility and local effectiveness of a novel bipolar plan-parallel expandable system for these larger tumours. METHODS AND MATERIALS: Eight consecutive patients with either unresectable colorectal liver metastases (CRLM in 6 patients), carcinoid liver metastases (1 patient) and hepatocellular carcinoma (HCC in 1 patient) of ≥3.5 cm were treated with bipolar RFA during laparotomy with ultrasound guidance. Early and late, major and minor complications were recorded. Local success was determined on 3-8 month follow-up CT scans of the upper abdomen. RESULTS: Nine CRLM, one carcinoid liver metastases and one HCC (3.5-6.6 cm) were ablated with bipolar RFA. Average ablation time was 16 min (range 6-29 min.). Two patients developed a liver abscess which required re-laparotomy. In both cases bowel surgery during the same session probably caused bacterial spill. There were no mortalities. The patients were released from hospital between 5 and 29 days after the procedure (median 12 days). The 6-12 month follow-up PET-CT scans showed signs for marginal RFA-site tumour recurrence in three patients with CRLM (3/11 lesions). CONCLUSION: Preliminary results suggest bipolar RFA to be a reasonably safe, fast and feasible technique which seems to improve local control for large size hepatic tumour ablations.