Radiofrequency ablation as first-line treatment in patients with early colorectal liver metastases amenable to surgery. Ann Surg. 2010;251:796-803. [PMID: 19858704 DOI: 10.1097/sla.0b013e3181bc9fae]

Thermal Ablation in the Management of Colorectal Cancer Patients with Oligometastatic Liver Disease

BACKGROUND

Surgical resection of limited colorectal liver disease improves long-term survival and can be curative in a subset of selected cases. Image-guided percutaneous ablation therapies have emerged as safe and effective alternative options for selected patients with unresectable colorectal liver metastases (CLM) that can be ablated with margins. Ablation causes focal destruction of tissue and has increasingly been shown to provide durable eradication of tumors.

METHODS

A selective review of literature was conducted in PubMed, focusing on recent studies reporting on the safety, efficacy, and long-term outcomes of percutaneous ablation modalities in the treatment of CLM. The present work gives an overview of the different ablation techniques, their current clinical indications, and reported outcomes from most recently published studies. The 'test of time' concept for using ablation as a first local therapy is also described.

RESULTS

There are several thermal ablative tools currently available, including radiofrequency ablation (RFA), microwave ablation, and cryoablation. Most data to date originated from the application of RFA. Adjuvant thermal ablation in the treatment of oligometastatic colon cancer liver disease offers improved oncologic outcomes. The ideal CLM amenable to percutaneous ablation is a solitary tumor with the largest diameter up to 3 cm that can be completely ablated with a sufficient margin. 5-year overall survival rates up to 70% after ablation of unresectable CLM have been reported. Pathologic confirmation of complete tumor necrosis with margins over 5 mm provides best long-term local tumor control by thermal ablation.

CONCLUSION

Current evidence suggests that percutaneous ablation as adjuvant to chemotherapy improves oncologic outcomes of patients with CLM. For small tumors that can be ablated completely with clear margins, percutaneous ablation may offer outcomes similar to those of surgery.

Hepatic Tumor Ablation

Tumor ablation is a safe and effective treatment available in the multidisciplinary care of the surgical oncology patient. The role of ablation is well established in the treatment of hepatocellular carcinoma and is becoming more accepted in the treatment of various malignancies metastatic to the liver, in particular colorectal cancer. Understanding the underlying technology, achieving appropriate applicator placement, using maximum energy delivery to create margins, and performing necessary adjunctive maneuvers are all required for successful tumor ablation.

Thermal ablation of colorectal liver metastases: a position paper by an international panel of ablation experts, The Interventional Oncology Sans Frontières meeting 2013

OBJECTIVES

Previous attempts at meta-analysis and systematic review have not provided clear recommendations for the clinical application of thermal ablation in metastatic colorectal cancer. Many authors believe that the probability of gathering randomised controlled trial (RCT) data is low. Our aim is to provide a consensus document making recommendations on the appropriate application of thermal ablation in patients with colorectal liver metastases.

METHODS

This consensus paper was discussed by an expert panel at The Interventional Oncology Sans Frontières 2013. A literature review was presented. Tumour characteristics, ablation technique and different clinical applications were considered and the level of consensus was documented.

RESULTS

Specific recommendations are made with regard to metastasis size, number, and location and ablation technique. Mean 31 % 5-year survival post-ablation in selected patients has resulted in acceptance of this therapy for those with technically inoperable but limited liver disease and those with limited liver reserve or co-morbidities that render them inoperable.

CONCLUSIONS

In the absence of RCT data, it is our aim that this consensus document will facilitate judicious selection of the patients most likely to benefit from thermal ablation and provide a unified interventional oncological perspective for the use of this technology.

KEY POINTS

• Best results require due consideration of tumour size, number, volume and location. • Ablation technology, imaging guidance and intra-procedural imaging assessment must be optimised. • Accepted applications include inoperable disease due to tumour distribution or inadequate liver reserve. • Other current indications include concurrent co-morbidity, patient choice and the test-of-time approach. • Future applications may include resectable disease, e.g. for small solitary tumours.

Liver Ablation: Best Practice

Tumor ablation in the liver has evolved to become a well-accepted tool in the management of increasing complex oncologic patients. At present, percutaneous ablation is considered first-line therapy for very early and early hepatocellular carcinoma and second-line therapy for colorectal carcinoma liver metastasis. Because thermal ablation is a treatment option for other primary and secondary liver tumors, an understanding of the underlying tumor biology is important when weighing the potential benefits of ablation. This article reviews ablation modalities, indications, patient selection, and imaging surveillance, and emphasizes technique-specific considerations for the performance of percutaneous ablation.

Ablative and catheter-directed therapies for colorectal liver and lung metastases

Increasing data on treatment of liver metastases with locoregional therapies have solidified the expanding role of interventional radiologists (IRs) in the treatment of liver metastases from colorectal cancer. Ablative approaches such as radiofrequency ablation and microwave ablation have shown durable eradication of tumors. Catheter-directed therapies such as transarterial chemoembolization, drug-eluting beads, yttrium-90 radioembolization, and intra-arterial chemotherapy ports represent potential techniques for managing patients with unresectable liver metastases. Understanding the timing and role of these techniques in multidisciplinary care of patients is crucial. Implementation of IRs for consultation enables better integration of these therapies into patients' overall care.

Colorectal cancer with potentially resectable hepatic metastases: optimizing treatment

Colorectal cancer is a common malignancy and often presents with synchronous or metachronous distant spread. For patients with hepatic metastases, resection is the principal curative option. Liberalization of the indications for hepatic resection has introduced a number of challenges related to the size, distribution, and number of metastases as well as the condition of the future liver remnant. Advances in systemic therapy have solidified its role as both an important adjunct to surgery and also for many patients as a mechanism to facilitate resection. In patients whose disease is marginally resectable as a consequence of the distribution of hepatic lesions that precludes complete resection or out of concern for the future liver remnant, a number of strategies have been advocated, including prehepatectomy systemic therapy, staged surgical approaches, ablative technologies, and preoperative portal vein embolization. It is the purpose of this review to discuss ways in which to optimize the treatment of patients with potentially resectable disease, specifically those who are judged to have "borderline" resectable situations.

Management of oligometastatic rectal cancer: is liver first?

Twenty percent of patients with rectal cancer present with synchronous liver metastases at the time of initial diagnosis. These patients can be treated with a curative intent, although the choice and sequence of treatment modalities are not well established and are commonly debated in multi-disciplinary tumor boards. In this article we review clinical evidence for various treatment approaches and attempt to formulate a pathway for clinicians to use in evaluating and managing these patients.

Hepatectomy vs radiofrequency ablation for colorectal liver metastasis: A propensity score analysis

AIM: To compare outcomes from radiofrequency ablation (RFA) and hepatectomy for treatment of colorectal liver metastasis (CRLM).

METHODS: From January 2000 to December 2009, 408 patients underwent curative intent treatment for CRLM. We excluded patients using the criteria: size of CRLM > 3 cm, number of CRLM ≥ 5, percutaneous RFA, follow-up period < 12 mo, double primary cancer, or treatment with both RFA and hepatectomy. We matched 51 patients who underwent RFA with 102 patients who underwent hepatectomy by propensity scores.

RESULTS: The median follow-up period was 45 mo (range, 12 mo to 158 mo). Hepatic recurrence was more frequent in the RFA than the hepatectomy group (P = 0.021) although extrahepatic recurrence curves were similar (P = 0.716). Survival curves of hepatectomy group were better than that of RFA for multiple, large (> 2 cm) CRLM (P = 0.034). However, survival curves were similar for single or small (≤ 2 cm) CRLM (P = 0.714, P = 0.740).

CONCLUSION: Hepatectomy is better than RFA for the treatment of CRLM. However, RFA might be suitable for selected patients with single, small (≤ 2 cm) CRLM.

Minimally invasive local therapies for liver cancer

Primary and metastatic liver tumors are an increasing global health problem, with hepatocellular carcinoma (HCC) now being the third leading cause of cancer-related mortality worldwide. Systemic treatment options for HCC remain limited, with Sorafenib as the only prospectively validated agent shown to increase overall survival. Surgical resection and/or transplantation, locally ablative therapies and regional or locoregional therapies have filled the gap in liver tumor treatments, providing improved survival outcomes for both primary and metastatic tumors. Minimally invasive local therapies have an increasing role in the treatment of both primary and metastatic liver tumors. For patients with low volume disease, these therapies have now been established into consensus practice guidelines. This review highlights technical aspects and outcomes of commonly utilized, minimally invasive local therapies including laparoscopic liver resection (LLR), radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), irreversible electroporation (IRE), and stereotactic body radiation therapy (SBRT). In addition, the role of combination treatment strategies utilizing these minimally invasive techniques is reviewed.

Outcomes of microwave ablation for colorectal cancer liver metastases: a single center experience

BACKGROUND AND OBJECTIVES

Surgical management of colorectal cancer liver metastases continues to evolve to optimize oncologic outcomes while maximizing parenchymal preservation. Long-term data after intraoperative microwave ablation are limited. This study investigates outcomes and patterns of recurrence in patients who underwent intraoperative microwave ablation.

METHODS

A retrospective analysis of 33 patients who underwent intraoperative microwave ablation of colorectal cancer liver metastases from 2009 to 2013 at our institution was performed. Perioperative and long-term data were reviewed to determine outcomes and patterns of recurrence.

RESULTS

A total of 49 tumors were treated, ranging 0.5-5.5 cm in size. Median Clavien-Dindo classification was one. Median follow-up was 531 days, with 13 (39.4%) patients presenting with a recurrence. Median time to first recurrence was 364 days. In those patients, 1 (7.8%) presented with an isolated local recurrence in the liver. Only 1 of 7 ablated tumors greater than 3 cm recurred (14.3%). Overall survival was 35.2% at 4 years, with a 19.3% disease-free survival at 3.5 years. No perioperative variables predicted systemic or local recurrence.

CONCLUSION

Intraoperative microwave ablation is a safe and effective modality for use in the treatment of colorectal cancer liver metastases in tumors as large as 5.5 cm in size.

Understanding the current status of image-guided ablation for metastatic colorectal disease

Colorectal metastases to the liver are increasingly being detected and accurately characterized at an earlier stage and even at the subcentimeter level. The oncological case for surgical resection of this disease is widely accepted. The advent of smaller volume disease has encouraged the development of in situ ablative technologies over the last two decades and the oncological efficacy of these procedures has continued to improve through stepwise developments in ablation devices and image guidance. This article provides an overview of these techniques, currently available and future technologies, and the imaging findings encountered. It also sets out the current position image-guided ablation merits alongside chemotherapy and surgical resection. In selected cases ablation for colorectal metastases can produce oncological outcomes equivalent to surgery and critically with less morbidity in an increasingly older patient population. We examine whether with careful patient selection, optimal technology, meticulous technique, and diligent follow-up, consistently reproducible high quality outcomes will be achieved in the next few years.

Patterns of recurrence following selective intraoperative radiofrequency ablation as an adjunct to hepatic resection for colorectal liver metastases

BACKGROUND AND OBJECTIVES

The purpose of this study was to analyze the patterns of recurrence following intraoperative radiofrequency ablation (RFA) combined with hepatic resection for patients with colorectal liver metastases (CLM).

METHODS

Patients undergoing liver resection (with or without RFA) for CLM were examined. Rates and patterns of disease recurrence, as well as overall survival were assessed using Kaplan-Meier and Cox analyses.

RESULTS

A total of 174 patients underwent liver resection for CLM (150 without and 24 with intraoperative RFA). RFA was used to treat 41 tumors (median 1.6 cm). The 3-year overall survival was 65.5% and 61.4% (adjusted HR 1.02, 95% CI 0.55-1.88). Median recurrence-free survival was 7.4 versus 12.7 months with RFA versus non-RFA, respectively (adjusted HR 1.51, 95% CI 0.94-4.42). On multivariate analysis, neither survival nor recurrence-free survival was significantly associated with RFA. In total, there were two RFA ablation zone local failures. An ablation site recurrence was the sole site in one patient (4.2%).

CONCLUSION

RFA was used as an adjunct to resection in patients with greater disease burden. Despite this, RFA was not significantly associated with a higher risk of local failure and was not associated with worse survival, when compared with liver resection alone.

Thermal ablation of liver metastases from colorectal cancer: radiofrequency, microwave and laser ablation therapies

Surgery is currently considered the treatment of choice for patients with colorectal cancer liver metastases (CRLM) when resectable. The majority of these patients can also benefit from systemic chemotherapy. Recently, local or regional therapies such as thermal ablations have been used with acceptable outcomes. We searched the medical literature to identify studies and reviews relevant to radiofrequency (RF) ablation, microwave (MW) ablation and laser-induced thermotherapy (LITT) in terms of local progression, survival indexes and major complications in patients with CRLM. Reviewed literature showed a local progression rate between 2.8 and 29.7 % of RF-ablated liver lesions at 12-49 months follow-up, 2.7-12.5 % of MW ablated lesions at 5-19 months follow-up and 5.2 % of lesions treated with LITT at 6-month follow-up. Major complications were observed in 4-33 % of patients treated with RF ablation, 0-19 % of patients treated with MW ablation and 0.1-3.5 % of lesions treated with LITT. Although not significantly different, the mean of 1-, 3- and 5-year survival rates for RF-, MW- and laser ablated lesions was (92.6, 44.7, 31.1 %), (79, 38.6, 21 %) and (94.2, 61.5, 29.2 %), respectively. The median survival in these methods was 33.2, 29.5 and 33.7 months, respectively. Thermal ablation may be an appropriate alternative in patients with CRLM who have inoperable liver lesions or have operable lesions as an adjunct to resection. However, further competitive evaluation should clarify the efficacy and priority of these therapies in patients with colorectal cancer liver metastases.

Recurrence location after resection of colorectal liver metastases influences prognosis

AIM

To assess the impact of first recurrence location on survival following surgery of colorectal liver metastases.

METHODS

A total of 265 consecutive patients with colorectal liver metastases undergoing liver surgery (2000-2011) were categorized according to first site of tumor recurrence. Time to recurrence (TTR) and overall survival (OS) were determined. Uni- and multivariate analysis were performed to identify factors associated with TTR and OS.

RESULTS

Median TTR was 1.16 years following liver resection, and 0.56 years following radiofrequency ablation (RFA). Intrahepatic recurrence following liver resection resulted in a significantly shorter median TTR compared to extrahepatic recurrence. Intrapulmonary recurrence was associated with superior survival compared to other recurrence locations. Such patterns were not observed in the RFA-treated group. Multivariate analysis identified the type of surgical treatment and extra-hepatic first-site recurrence (other than lung) as independent predictors for OS. Pre-operative chemotherapy and simultaneous intrahepatic and extrahepatic recurrence were independent predictors for both TTR and OS.

CONCLUSIONS

Patients with intrahepatic recurrence following liver resection have a significantly shorter TTR and OS when compared to patients developing extrahepatic recurrence. Pulmonary recurrence following resection is associated with longer survival. Simultaneous intra- and extrahepatic recurrence is an independent prognostic factor for TTR and OS.

Locally ablative therapies for primary and metastatic liver cancer

Locally ablative therapies have an increasing role in the effective multidisciplinary approach towards the treatment of both primary and metastatic liver tumors. In patients who are not considered surgical candidates and have low volume disease, these therapies have now become established into consensus practice guidelines. A large range of therapeutic options exist including percutaneous ethanol injection (PEI), radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation, percutaneous laser ablation (PLA), irreversible electroporation (IRE), stereotactic body radiation therapy (SBRT) and high intensity focused ultrasound (HIFU); each having benefits and drawbacks. The greatest body of evidence supporting clinical utility in the liver currently exists for RFA, with PEI having fallen out of favor. MWA, IRE, SBRT and HIFU are relatively nascent technologies, and outcomes data supporting their use is promising. Future directions of ablative therapies include tandem approaches to improve efficacy in the treatment of liver tumors.

Radiofrequency ablation for colorectal liver metastases

The management of hepatic metastases from colorectal cancer (HMCRC) is multimodal including chemotherapy, surgical resection, radiation therapy, and focused destruction technologies. Radiofrequency ablation (RFA) is the most commonly used focused destruction technology. It represents a therapeutic option that may be potentially curative in cases where surgical excision is contra-indicated. It also increases the number of candidates for surgical resection among patients whose liver metastases were initially deemed unresectable. This article explains the techniques, indications, and results of radiofrequency ablation in the treatment of hepatic colorectal metastases.

Percutaneous imaging-guided cryoablation of liver tumors: predicting local progression on 24-hour MRI

OBJECTIVE

The purpose of this study was to determine which MRI features observed 24 hours after technically successful percutaneous cryoablation of liver tumors predict subsequent local tumor progression and to describe the evolution of imaging findings after cryoablation.

MATERIALS AND METHODS

Thirty-nine adult patients underwent technically successful imaging-guided percutaneous cryoablation of 54 liver tumors (hepatocellular carcinoma, 8; metastases, 46). MRI features pertaining to the tumor, ablation margin, and surrounding liver 24 hours after treatment were assessed independently by two readers. Fisher exact or Wilcoxon rank sum tests (significant p values < 0.05) were used to compare imaging features in patients with and without subsequent local tumor progression. Imaging features of the ablation margin, treated tumor, and surrounding liver were evaluated on serial MRI in the following year.

RESULTS

A minimum ablation margin of 3 mm or less was observed in 11 (78.6%) of 14 tumors with and 15 of 40 (37.5%) without progression (p = 0.012). A blood vessel bridging the ablation margin was noted in 11 of 14 (78.6%) tumors with and nine of 40 (22.5%) without progression (p < 0.001). The incidence of tumor enhancement 24 hours after cryoablation was similar for tumors with (10/14, 71.4%) or without (25/40, 62.5%) local progression (p = 0.75). MRI enabled assessment of the entire cryoablation margin in 49 of 54 (90.7%) treated tumors.

CONCLUSION

MRI features at 24 hours after liver cryoablation that were predictive of local tumor progression included a minimum ablation margin less than or equal to 3 mm and a blood vessel bridging the ablation margin. Persistent tumor enhancement is common after liver cryoablation and does not predict local tumor progression.

Comparative analysis of radiofrequency ablation and resection for resectable colorectal liver metastases

AIM: To evaluate the therapeutic efficacy of radiofrequency ablation (RFA) for resectable colorectal liver metastases (CRLM) compared with that of resection.

METHODS: Between June 2004 and June 2009, we retrospectively analyzed 29 patients with resectable CRLMs; 17 patients underwent RFA, and 12 underwent hepatic resection. All of the patients were informed about the treatment modalities and were allowed to choose either of them. RFA including an intraoperative approach was performed by a radiologist; otherwise, hepatic resection was performed by a surgeon. Comparative analysis of the two groups was performed, including comparisons of gender, age, and clinical outcomes, such as primary tumor stage and survival rates.

RESULTS: The mean tumor size was significantly larger in the resection group (3.59 cm vs 2.02 cm, P < 0.01), and the 5-year overall survival (OS) rate for all patients was 44.7%. There was no difference in the 5-year OS rates between the RFA and resection groups (37.8% vs 66.7%). Univariate analysis indicated significantly lower 5-year OS rates for patients with a tumor size > 3 cm. The 5-year disease-free survival (DFS) rates were 17.6% and 22.2% in the RFA and resection groups, respectively (P = 0.119). Univariate analysis revealed that in cases of male gender, age > 65 years, T stage < IV, absence of lymphatic metastasis, and tumor size > 3 cm, RFA resulted in significantly inferior 5-year DFS rates compared with surgical resection.

CONCLUSION: Surgical resection revealed superior outcomes in the treatment of resectable CRLMs, particularly in cases with a hepatic tumor size > 3 cm.

Combination therapy with local radiofrequency ablation and systemic vaccine enhances antitumor immunity and mediates local and distal tumor regression

Purpose

Radiofrequency ablation (RFA) is a minimally invasive energy delivery technique increasingly used for focal therapy to eradicate localized disease. RFA-induced tumor-cell necrosis generates an immunogenic source of tumor antigens known to induce antitumor immune responses. However, RFA-induced antitumor immunity is insufficient to control metastatic progression. We sought to characterize (a) the role of RFA dose on immunogenic modulation of tumor and generation of immune responses and (b) the potential synergy between vaccine immunotherapy and RFA aimed at local tumor control and decreased systemic progression.

Experimental Design

Murine colon carcinoma cells expressing the tumor-associated (TAA) carcinoembryonic antigen (CEA) (MC38-CEA⁺) were studied to examine the effect of sublethal hyperthermia in vitro on the cells’ phenotype and sensitivity to CTL-mediated killing. The effect of RFA dose was investigated in vivo impacting (a) the phenotype and growth of MC38-CEA⁺ tumors and (b) the induction of tumor-specific immune responses. Finally, the molecular signature was evaluated as well as the potential synergy between RFA and poxviral vaccines expressing CEA and a TRIad of COstimulatory Molecules (CEA/TRICOM).

Results

In vitro, sublethal hyperthermia of MC38-CEA⁺ cells (a) increased cell-surface expression of CEA, Fas, and MHC class I molecules and (b) rendered tumor cells more susceptible to CTL-mediated lysis. In vivo, RFA induced (a) immunogenic modulation on the surface of tumor cells and (b) increased T-cell responses to CEA and additional TAAs. Combination therapy with RFA and vaccine in CEA-transgenic mice induced a synergistic increase in CD4⁺ T-cell immune responses to CEA and eradicated both primary CEA⁺ and distal CEA^– s.c. tumors. Sequential administration of low-dose and high-dose RFA with vaccine decreased tumor recurrence compared to RFA alone. These studies suggest a potential clinical benefit in combining RFA with vaccine in cancer patients, and augment support for this novel translational paradigm.

Interventional oncologic approaches to liver metastases

Metastatic liver disease is the most common cause of death in cancer patients. Complete surgical resection is currently considered the only curative treatment, with only about 25% of patients being amenable to surgery. Therefore, a variety of interventional oncologic techniques have been developed for treating secondary liver malignancies. The aim of these therapies is either to allow patients with unresectable tumors to become surgical candidates, provide curative treatment options in nonsurgical candidates, or improve survival in a palliative or even curative approach. Among these interventional therapies are transcatheter therapies such as portal vein embolization, hepatic artery infusion chemotherapy, transarterial chemoembolization, and radioembolization, as well as interstitial techniques, particularly radiofrequency ablation as the most commonly applied technique. The rationale, application and clinical results of each of these techniques are reviewed on the basis of the current literature. Future prospects such as gene therapy and immunotherapy are introduced.

Radiofrequency ablation versus resection for colorectal cancer liver metastases: a meta-analysis

BACKGROUND

No randomized controlled trial (RCT) has yet been performed to provide the evidence to clarify the therapeutic debate on liver resection (LR) and radiofrequency ablation (RFA) in treating colorectal liver metastases (CLM). The meta-analysis was performed to summarize the evidence mostly from retrospective clinical trials and to investigate the effect of LR and RFA.

METHODOLOGY/PRINCIPAL FINDINGS

Systematic literature search of clinical studies was carried out to compare RFA and LR for CLM in Pubmed, Embase and the Cochrane Library Central databases. The meta-analysis was performed using risk ratio (RR) and random effect model, in which 95% confidence intervals (95% CI) for RR were calculated. Primary outcomes were the overall survival (OS) and disease-free survival (DFS) at 3 and 5 years plus mortality and morbidity. 1 prospective study and 12 retrospective studies were finally eligible for meta-analysis. LR was significantly superior to RFA in 3 -year OS (RR 1.377, 95% CI: 1.246-1.522); 5-year OS (RR: 1.474, 95%CI: 1.284-1.692); 3-year DFS (RR 1.735, 95% CI: 1.483-2.029) and 5-year DFS (RR 2.227, 95% CI: 1.823-2.720). The postoperative morbidity was higher in LR (RR: 2.495, 95% CI: 1.881-3.308), but no significant difference was found in mortality between LR and RFA. The data from the 3 subgroups (tumor<3 cm; solitary tumor; open surgery or laparoscopic approach) showed significantly better OS and DFS in patients who received surgical resection.

CONCLUSIONS/SIGNIFICANCES

Although multiple confounders exist in the clinical trials especially the bias in patient selection, LR was significantly superior to RFA in the treatment of CLM, even when conditions limited to tumor<3 cm, solitary tumor and open surgery or laparoscopic (lap) approach. Therefore, caution should be taken when treating CLM with RFA before more supportive evidences for RFA from RCTs are obtained.

Thermal tumor ablation therapy for colorectal cancer hepatic metastasis

Surgical resection for colorectal hepatic metastases (CRHM) is the preferred treatment for suitable candidates, and the only potentially curative modality. However, due to various limitations, the majority of patients with CRHM are not candidates for liver resection. In recent years, there has been an increasing interest in the role of thermal tumor ablation (TTA) as a component of combined resection-ablation strategies, staged hepatic resections, or as standalone adjunct treatment for patients with CRHM. Thus, ablative approaches have expanded the group of patients with CRHM that may benefit from liver-directed treatment strategies.

Retrospective review of efficacy of radiofrequency ablation for treatment of colorectal cancer liver metastases from a Canadian perspective

PURPOSE

A retrospective single-center review of ultrasound-guided radiofrequency ablation (RFA) treatment of colorectal cancer liver metastases was performed. This study reviews the primary and secondary technical effectiveness, overall survival of patients, recurrence-free survival, tumour-free survival, rates of local recurrence, and postprocedural RFA complications. Technical effectiveness and rates of complication with respect to tumour location and size were evaluated. Our results were compared with similar studies from Europe and North America.

METHODS

A total of 63 patients (109 tumours) treated with RFA between February 2004 and December 2009 were reviewed. Average and median follow-up time was 19.4 and 16.5 months, respectively (range, 1-54 months). Data from patient charts, pathology, and Picture Archiving and Communication System was integrated into an Excel database. Statistical Analysis Software was used for statistical analysis.

RESULTS

Primary and secondary technical effectiveness of percutaneous and intraoperative RFA were 90.8% and 92.7%, respectively. Average (SE) tumour-free survival was 14.4 ± 1.4 months (range, 1-43 months), and average (SE) recurrence-free survival was 33.5 ± 2.3 months (range, 2-50 months). Local recurrence was seen in 31.2% of treated tumours (range, 2-50 months) (34/109). Overall survival was 89.4% at 1 year, 70.0% at 2 years, and 38.1% at 3 years, with an average (SE) overall survival of 37.0 ± 2.8 months. There were 14 postprocedural complications. There was no statistically significant difference in technical effectiveness for small tumours (1-2 cm) vs intermediate ones (3-5 cm). There was no difference in technical effectiveness for peripheral vs parenchymal tumours.

CONCLUSIONS

This study demonstrated good-quality outcomes for RFA treatment of colorectal cancer liver metastases from a Canadian perspective and compared favorably with published studies.

Radiofrequency ablation in the treatment of liver metastases from colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the most common malignant tumour and the third leading cause of cancer deaths in USA. For advanced CRC, the liver is the first site of metastatic disease; approximately 50 % of patients with CRC will develop liver metastases either synchronously or metachronously within 2 years after primary diagnosis. Hepatic resection (HR) is the only curative option, but only 15-20% of patients with liver metastases from CRC (CRLMs) are suitable for surgical standard treatment. In patients with unresectable CRLMs downsizing chemotherapy can improve resectability (16%). Modern systemic chemotherapy represents the only significant treatment for unresectable CRLMs. However several loco-regional treatments have been developed: hepatic arterial infusion (HAI), cryosurgical ablation (CSA), radiofrequency ablation (RFA), microwave ablation and selective internal radion treatment (SIRT). During the past decade RFA has superseded other ablative therapies, due to its low morbidity, mortality, safety and patient acceptability.

OBJECTIVES

The objective of this study was to systematically review the role of radiofrequency ablation (RFA) in the treatment of CRLMs.

SEARCH METHODS

We performed electronic searches in the following databases:CENTRAL, MEDLINE and EMBASE. Current trials were identified through the Internet using the Clinical-Trials.gov site (to January 2, 2012) and ASCO Proceedings. The reference lists of identified trials were reviewed for additional studies.

SELECTION CRITERIA

Randomized clinical trials (RCTs), quasi-randomised or controlled clinical trials (CCTs) comparing RFA to any other therapy for CRLMs were included. Observational study designs including comparative cohort studies comparing RFA to another intervention, single arm cohort studies or case control studies have been included if they have: prospectively collected data, ten or more patients; and have a mean or median follow-up time of 24 months. Patients with CRLMs who have no contraindications for RFA. Patients with unresectable extra-hepatic disease were also included.Trials have been considered regardless of language of origin.

DATA COLLECTION AND ANALYSIS

A total of 1144 records were identified through the above electronic searching. We included 18 studies: 10 observational studies, 7 Clinical Controlled Trials (CCTs) and an additional 1 Randomized Clinical Trial (RCT) (abstract) identified by hand searching in the 2010 ASCO Annual Meeting. The most appropriate way of summarizing time-to-event data is to use methods of survival analysis and express the intervention effect as a hazard ratio. In the included studies these outcome are mostly reported as dichotomous data so we should have asked authors research data for each participant and perform Individual Patient Data (IPD) meta-analysis. Given the study design and low quality of included studies we decided to give up and not to summarize these data.

MAIN RESULTS

Seventeen studies were not randomised and this increases the potential for selection bias. In addition, there was imbalance in the baseline characteristics of the participants included in all studies. All studies were classified as having a elevate risk of bias. The assessment of methodological quality of all non-randomized studies included in meta-analysis performed by the STROBE checklist has allowed us to identify several methodological limits in most of the analysed studies. At present, the information from the single RCT included (Ruers 2010) comes from an abstract of 2010 ASCO Annual Meeting where the allocation concealment was not reported; however in original protocol allocation concealment was adequately reported (EORTC 40004 protocol). The heterogeneity regarding interventions, comparisons and outcomes rendered the data not suitable.

AUTHORS' CONCLUSIONS

This systematic review gathers information from several controlled clinical trials and observational studies which are vulnerable to different types of bias. The imbalance between characteristics of patients in the allocated groups appears to be the main concern. Only one randomised clinical trial (published as an abstract), comparing 60 patients receiving RFA plus CT versus 59 patients receiving CT alone, was identified. This study showed that PFS was significantly higher in the group that received RFA. However, it was not able to provide information on overall survival. In conclusion, evidence from the included studies are insufficient to recommend RFA for a radical oncological treatment of CRLMs.

Radiofrequency ablation for colorectal liver metastases: prognostic factors in non-surgical candidates

PURPOSE

To determine prognostic factors in patients with colorectal liver metastases who were not surgical candidates and received liver radiofrequency (RF) ablation.

MATERIALS AND METHODS

RF ablation was done for 141 colorectal liver metastases in 84 patients. There were 63 (75.0 %, 63/84) males and 21 (25.0 %, 21/84) females, with a mean age of 64.6 ± 10.3. The mean maximum tumor diameter was 2.3 ± 1.4 cm (range 0.5-9.0 cm). Extrahepatic metastases were associated at the time of liver RF ablation in 23 patients (27.4 %, 23/84), and 12 (14.3 %, 12/84) had lung metastases considered controllable by planned lung RF ablation. Prognostic factors were evaluated by univariate and multivariate analyses.

RESULTS

There was no procedure-related mortality. The 1-, 3-, and 5-year overall survival rates were 90.6 % (95 %CI, 83.9-97.2 %), 44.9 % (95 %CI, 31.8-57.9 %), and 20.8 % (95 %CI, 7.3-34.3 %), respectively, with a median survival of 34.9 months. The univariate analysis showed that tumor diameter larger than 3 cm, tumor multiplicity, uncontrollable extrahepatic disease, and previous chemotherapy history were significantly worse prognostic factors. The former three factors remained significant for worse prognosis in the multivariate Cox model. Extrahepatic disease was not a prognostic factor when it could be controlled.

CONCLUSION

Tumor size and number, and uncontrollable extrahepatic metastases were significant prognostic factors.

Does Radiofrequency Ablation Add to Chemotherapy for Unresectable Liver Metastases?

In patients with unresectable colorectal liver metastases (CRLM), radiofrequency ablation (RFA) might be a good alternative, whenever possible. In contrast to systemic therapy, the aim of RFA is to achieve complete local tumor control in an attempt to provide long-term survival. In this article we discuss the available evidence regarding the treatment of patients with unresectable CRLM, focusing on RFA in conjunction with modern systemic therapies. We observed that the available evidence in the existing literature is limited, and often consists of level 2 and 3 evidence, thereby hampering any firm conclusions. Nonetheless, RFA seems superior to chemotherapy alone in patients with liver-only disease amenable for RFA. However, the combination of RFA and chemotherapy has been demonstrated to be feasible and safe, lending support to the concept of RFA followed by chemotherapy, in order to reduce local recurrence rates and prolong survival.

Therapeutic potential of surgery for metastatic colorectal cancer

Evidence of the clinical benefit of surgery or metastasectomy for metastatic colorectal cancer to disease sites including the liver, lung, peritoneum, and pelvis as a potentially curative option is now available in the literature. The oncologic outcome of this treatment strategy achieves 5-year survival ranging between 20% and 50%. These survival gains have not been previously observed in the management of metastatic colorectal cancer. Treatment of potential surgical candidates requires a combined modality approach with systemic therapies to achieve macroscopic tumor removal and microscopic targeting of tumor deposits to achieve disease control. In nonsurgical candidates, systemic therapy, radiation therapy, and interventional oncology procedures may potentially facilitate sufficient disease downstaging for surgery. The purpose of this article is to provide a comprehensive review of the therapeutic advances in the surgical management of metastatic colorectal cancer.

Patterns of recurrence after ablation of colorectal cancer liver metastases

PURPOSE

To determine the local recurrence rate and factors associated with recurrence after intraoperative ablation of colorectal cancer liver metastases.

METHODS

A retrospective analysis of a prospectively maintained database was performed for patients who underwent ablation of a hepatic colorectal cancer metastasis in the operating room from April 1996 to March 2010. Kaplan-Meier survival curves and Cox models were used to determine recurrence rates and assess significance.

RESULTS

Ablation was performed in 10% (n = 158 patients) of all cases during the study period. Seventy-eight percent were performed in conjunction with a liver resection. Of the 315 tumors ablated, most tumors were ≤ 1 cm in maximum diameter (53%). Radiofrequency ablation was used to treat most of the tumors (70%). Thirty-six tumors (11%) had local recurrence as part of their recurrence pattern. Disease recurred in the liver or systemically after 212 tumors (67%) were ablated. On univariate analysis, tumor size greater than 1 cm was associated with a significantly increased risk of local recurrence (hazard ratio 2.3, 95% confidence interval 1.2-4.5, P = 0.013). The 2 year ablation zone recurrence-free survival was 92% for tumors ≤ 1 cm compared to 81% for tumors >1 cm. On multivariate analysis, tumor size of >1 cm, lack of postoperative chemotherapy, and use of cryotherapy were significantly associated with a higher local recurrence rate.

CONCLUSIONS

Intraoperative ablation appears to be highly effective treatment for hepatic colorectal tumors ≤ 1 cm.

Minimally invasive evaluation and treatment of colorectal liver metastases

Minimally invasive techniques used in the evaluation and treatment of colorectal liver metastases (CRLMs) include ultrasonography (US), computed tomography, magnetic resonance imaging, percutaneous and operative ablation therapy, standard laparoscopic techniques, robotic techniques, and experimental techniques of natural orifice endoscopic surgery. Laparoscopic techniques range from simple staging laparoscopy with or without laparoscopic intraoperative US, through intermediate techniques including simple liver resections (LRs), to advanced techniques such as major hepatectomies. Hereins, we review minimally invasive evaluation and treatment of CRLM, focusing on a comparison of open LR (OLR) and minimally invasive LR (MILR). Although there are no randomized trials comparing OLR and MILR, nonrandomized data suggest that MILR compares favorably with OLR regarding morbidity, mortality, LOS, and cost, although significant selection bias exists. The future of MILR will likely include expanding criteria for resectability of CRLM and should include both a patient registry and a formalized process for surgeon training and credentialing.

The management of solitary colorectal liver metastases

Surgical resection of solitary colorectal liver metastases is associated with long-term survival. Radiofrequency ablation used as the primary treatment option of solitary resectable colorectal liver metastases is associated with an increased risk of local recurrence that generally leads to worse survival compared to resection. In contrast with treatment of other hepatic malignancies, radiofrequency ablation is not equivalent to resection for colorectal liver metastases and should not be used as an alternative but limited to inoperable patients. Although overall survival rate after resection can be up to 71% at 5 years, the majority of patients develop recurrence. Preoperative chemotherapy contributes to decrease the risk of recurrence after resection of colorectal liver metastases. In patients with advanced solitary colorectal liver metastasis initially non suitable for resection, chemotherapy and portal vein embolization contribute to increase the number of surgical candidates whereas radiofrequency is rarely an option.

Radiofrequency ablation vs hepatic resection for solitary colorectal liver metastasis: A meta-analysis

AIM: To evaluate the comparative therapeutic efficacy of radiofrequency ablation (RFA) and hepatic resection (HR) for solitary colorectal liver metastases (CLM).

METHODS: A literature search was performed to identify comparative studies reporting outcomes for both RFA and HR for solitary CLM. Pooled odds ratios (OR) with 95% confidence intervals (95% CI) were calculated using either the fixed effects model or random effects model.

RESULTS: Seven nonrandomized controlled trials studies were included in this analysis. These studies included a total of 847 patients: 273 treated with RFA and 574 treated with HR. The 5 years overall survival rates in the HR group were significantly better than those in the RFA group (OR: 0.41, 95% CI: 0.22-0.90, P = 0.008). RFA had a higher rate of local intrahepatic recurrence compared to HR (OR: 4.89, 95% CI: 1.73-13.87, P = 0.003). No differences were found between the two groups with respect to postoperative morbidity and mortality.

CONCLUSION: HR was superior to RFA in the treatment of patients with solitary CLM. However, the findings have to be carefully interpreted due to the lower level of evidence.

Stereotactic body radiotherapy for colorectal liver metastases: a pooled analysis

BACKGROUND

This study was undertaken to determine outcomes of stereotactic body radiotherapy for colorectal liver metastases in a pooled patient cohort.

METHODS

Patients with colorectal liver metastases from 3 institutions were included if they had 1 to 4 lesions, received 1 to 6 fractions of stereotactic body radiotherapy, and had radiologic imaging ≥ 3 months post-treatment. Sixty-five patients with 102 lesions treated from August 2003 to May 2009 were retrospectively analyzed. A tumor control probability (TCP) model was used to estimate the 3-fraction dose required for > 90% local control after converting the schedule into biologically equivalent dose (BED), single-fraction equivalent dose, or linear quadratic model-based single-fraction dose.

RESULTS

Forty-seven (72%) patients had ≥ 1 chemotherapy regimen before stereotactic body radiotherapy, and 27 (42%) patients had ≥ 2 regimens. The median follow-up was 1.2 years (range, 0.3-5.2 years). The median dose was 42 gray (Gy; range, 22-60 Gy). When evaluated separately by multivariate analysis, total dose (P = .0015), dose/fraction (P = .003), and BED (P = .004) all correlated with local control by lesion. On multivariate analysis, nonactive extrahepatic disease was associated with overall survival (OS; P = .046), and sustained local control was closely correlated (P = .06). By using single-fraction equivalent dose, BED, or linear quadratic model-based single-fraction dose in the TCP model, the estimated dose range needed for 1-year local control > 90% is 46 to 52 Gy in 3 fractions.

CONCLUSIONS

Liver stereotactic body radiotherapy is well tolerated and effective for colorectal liver metastases. The strong correlation between local control and OS supports controlling hepatic disease even for heavily pretreated patients. For a 3-fraction regimen of stereotactic body radiotherapy, a prescription dose of ≥ 48 Gy should be considered, if normal tissue constraints allow.

Comparative analysis of radiofrequency ablation and surgical resection for colorectal liver metastases

PURPOSE

To evaluate the comparative therapeutic efficacy of radiofrequency ablation (RFA) and hepatic resection for the treatment of colorectal liver metastasis (CRLM).

METHODS

Between 1996 and 2008, 177 patients underwent RFA, 278 underwent hepatic resection and 27 underwent combination therapy for CRLM. Comparative analysis of clinical outcomes was performed including number of liver metastases, tumor size, and time of CRLM.

RESULTS

Based on multivariate analysis, overall survival (OS) correlated with the number of liver metastases and the use of combined chemotherapy (P < 0.001, respectively). Disease-free survival (DFS) also correlated with the number of liver metastases (P < 0.001). In the 226 patients with solitary CRLM < 3 cm, OS and DFS rates did not differ between the RFA group and the resection group (P = 0.962 and P = 0.980). In the 70 patients with solitary CRLM ≥ 3 cm, DFS was significantly lower in the RFA group as compared with the resection group (P = 0.015).

CONCLUSION

The results indicate that RFA may be a safe alternative treatment for solitary CRLM less than 3 cm, with outcomes equivalent to those achieved with hepatic resection. A randomized controlled study comparing RFA and resection for patients with single small metastasis would help to determine the most efficient treatment modalities for CRLM.

Hepatectomy for recurrent colorectal liver metastases after radiofrequency ablation

BACKGROUND

The results of surgery for recurrent colorectal liver metastases (CLM) after radiofrequency ablation (RFA) have not been evaluated.

METHODS

From 1993 to 2009, data on patients who underwent resection or RFA for recurrent CLM were collected prospectively. Inclusion criteria for this study were RFA as initial treatment for CLM and resection of recurrent CLM after RFA. Postoperative results and oncological outcomes were analysed.

RESULTS

Twenty-eight patients (median number of tumours 1 (1-3), median size 2·8 (2·0-4·0) cm) met the inclusion criteria. Of these, 22 had recurrence at the site of RFA only, two developed new lesions, whereas four had both recurrent and de novo metastases. At the time of resection, patients had a median of 1 (1-13) CLM with a median maximum tumour diameter of 5·0 (1·8-11·0) cm, significantly larger than at the time of RFA (P = 0·021). Ninety-day postoperative morbidity and mortality rates were 46 per cent (13 of 28) and 7 per cent (2 of 28) respectively. After a median follow-up of 35 (0-70) months, 3-year overall and disease-free survival rates calculated by Kaplan-Meier analysis were 60 and 29 per cent respectively. Plasma carcinoembryonic antigen level over 5 ng/ml at the time of resection and a rectal primary tumour were associated with worse survival (P = 0·041 and P = 0·021 respectively).

CONCLUSION

Resection for recurrence after RFA is associated with significant morbidity and modest long-term benefit.

Therapeutic efficacy of combined intraoperative ablation and resection for colorectal liver metastases: an international, multi-institutional analysis

BACKGROUND

Only 10-25% of patients presenting with colorectal liver metastases (CRLM) are amenable to hepatic resection. By combining resection and ablation, the number of patients eligible for surgery can be expanded. We sought to determine the efficacy of combined resection and ablation for CRLM.

METHODS

Between 1984 and 2009, 1,425 patients who underwent surgery for CRLM were queried from an international multi-institutional database. Of these, 125 patients underwent resection combined with ablation as the primary mode of treatment.

RESULTS

Patients presented with a median of six lesions. The median number of lesions resected was 4; the median number of lesions ablated was 1. At last follow-up, 84 patients (67%) recurred with a median disease-free interval of 15 months. While total number of lesions treated (hazard ratio (HR) = 1.47, p = 0.23) and number of lesions resected (HR = 1.18, p = 0.43) did not impact risk of intrahepatic recurrence, the number of lesions ablated did (HR = 1.36, p = 0.05). Overall 5-year survival was 30%. Survival was not influenced by the number of lesions resected or ablated (both p > 0.05).

CONCLUSION

Combined resection and ablation is associated with long-term-survival in a subset of patients; however, recurrence is common. The number of lesions ablated increases risk of intrahepatic recurrence but does not impact overall survival.

Treatment of liver colorectal metastases: role of laparoscopy, radiofrequency ablation, and microwave coagulation

Up to 50% of patients with colorectal cancer will develop metastatic disease in the liver. While surgical extirpation remains the best option for long-term survival, several complementary modalities such as laparoscopy, radiofrequency ablation, and microwave coagulation have gained wide acceptance as primary and adjunct therapies for both resectable and unresectable disease. This review will focus on the application and outcome of these techniques in patients with colorectal liver metastases.

Resection versus no intervention or other surgical interventions for colorectal cancer liver metastases

BACKGROUND

About one in four of patients with metastatic colorectal cancer have metastases isolated to the liver, of which 10% to 25% are eligible for ablation of the liver metastases, improving the five year survival rate. Treatments include hepatic resection and other modalities using cryosurgery and radiofrequency thermal ablation. Although new modalities allow safe ablation of liver metastases without the need for surgical intervention, there are still no clear guidelines on the appropriate management of patients with colorectal cancer and hepatic metastases.

OBJECTIVES

The primary objectives were to compare resection of liver metastases to no intervention and other modalities of intervention (including cryosurgery and radiofrequency ablation) in terms of the benefits and harms for each intervention.

SEARCH STRATEGY

Searches were conducted of the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE databases up to October 2006. In addition, references were scrutinized in identified eligible trials.

SELECTION CRITERIA

Only randomized controlled trials reporting patients (regardless of age and sex) who had had curative surgery for adenocarcinoma of the colon or rectum, had been diagnosed with liver metastases and who were eligible for liver resection (i.e. with no evidence of primary or metastatic cancer elsewhere) were considered.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data using a form designed for this review. Discrepancies were resolved by consensus.

MAIN RESULTS

Only one trial involving 123 people (87 male 36 female) was included. The data from this ten year prospective, randomized clinical trial suggest that hepatic cryosurgery is effective in the treatment of resectable and nonresectable liver metastases. The results show intra-operative tumor reduction (>/=90% or </= 97%) and extended higher survival in these patients. The study indicated a five year and ten year survival rate of 44% and 19% after cryosurgery, respectively. However, it was not possible to separate out and unravel the outcomes data that related only to the participants (66.6%) with liver metastases from colorectal cancer as opposed to those with liver metastases from other primary tumors.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to support a single approach, either surgical or non-surgical, for the management of colorectal liver metastases. Therefore, treatment decisions should continue to be based on individual circumstances and clinician's experience. The authors conclude that local ablative therapies are probably useful, but that they need to be further evaluated in a randomized controlled trial.