Radio-frequency ablation of colorectal liver metastases in 167 patients

ACR Appropriateness Criteria® Management of Liver Cancer: 2022 Update

The treatment and management of hepatic malignancies can be complex because it encompasses a variety of primary and metastatic malignancies and an assortment of local and systemic treatment options. When to use each of these treatments is critical to ensure the most appropriate care for patients. Interventional radiologists have a key role to play in the delivery of a variety of liver directed treatments including percutaneous ablation, transarterial embolization with bland embolic particles alone, transarterial chemoembolization (TACE) with injection of a chemotherapeutic emulsion, and transarterial radioembolization (TARE). Based on 9 clinical variants, the appropriateness of each treatment is described in this document. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Practical utility of liver segmentation methods in clinical surgeries and interventions

Clinical imaging (e.g., magnetic resonance imaging and computed tomography) is a crucial adjunct for clinicians, aiding in the diagnosis of diseases and planning of appropriate interventions. This is especially true in malignant conditions such as hepatocellular carcinoma (HCC), where image segmentation (such as accurate delineation of liver and tumor) is the preliminary step taken by the clinicians to optimize diagnosis, staging, and treatment planning and intervention (e.g., transplantation, surgical resection, radiotherapy, PVE, embolization, etc). Thus, segmentation methods could potentially impact the diagnosis and treatment outcomes. This paper comprehensively reviews the literature (during the year 2012-2021) for relevant segmentation methods and proposes a broad categorization based on their clinical utility (i.e., surgical and radiological interventions) in HCC. The categorization is based on the parameters such as precision, accuracy, and automation.

Characteristic changes of the ablation zone on contrast-enhanced computed tomography after radiofrequency ablation of hepatic metastases

Purpose:

Size and density measurements of the ablation zones on contrast-enhanced computed tomography (CT) after radiofrequency ablation (RFA) of hepatic metastases of primary breast or colorectal cancer were acquired over time.

Materials and Methods:

Twenty-five liver metastases [colorectal cancer (CRC): n = 16; mean size: 19.6 ± 8.5 mm; breast cancer (BC): n = 9; 27.9 ± 13.6 mm] in 15 patients (CRC: n = 11; age: 65.4 ± 6.5 years; BC: n = 4; 62.0 ± 13.8 years) treated by RFA were included in this retrospective study. All patients had undergone postinterventional serial follow-up using multidetector CT (MDCT) (1 day/1/4/7/10/14/18/23/>24 months) without evidence of local tumor recurrence during the follow-up. The ablation zones were evaluated using a commercial software tool (Syngo CT Oncology) in order to determine volumetric, RECIST-, WHO- and density changes over the course of time. Results were compared by applying repeated measures analysis of variance and displayed graphically.

Results:

The RF ablation zones demonstrated significant shrinkage (P ≤ 0.05) over the first 7 months (volume, RECIST, WHO) of the follow-up. Follow-up after 7 months did not show any significant changes in size (P > 0.05) (mean volume (ml): 55.2/34.7/26.3/16.5/12.7/10.0/8.9/8.1/7.5; RECIST (mm): 58.7/49.3/43.7/37.8/34.2/31.3/29.1/27.3/24.8; WHO (mm²): 2458.3/1769.3/1341.8/1027.1/870.1/720.2/649.0/570.4/511.3). Mean density values decreased significantly between 1 day (58.9 HU) and 1 month (47.5 HU) after the procedure.

Conclusion:

Typical changes in size and density values of RF-induced, recurrence-free ablation zones after RFA of hepatic metastases of colorectal and breast cancer were acquired, showing a significant decrease in density of the ablation zone within the first month and significant shrinkage within the first 7 months after RFA.

The prognosis of radiofrequency ablation versus hepatic resection for patients with colorectal liver metastases: A systematic review and meta-analysis based on 22 studies

BACKGROUND

Though hepatic resection (HR) is the standard local therapy for patients with colorectal cancer liver metastases (CRLMs), currently, radiofrequency ablation (RFA) may play an alternative role for elderly and vulnerable patients with various organ dysfunctions. This study aims to compare the prognosis of RFA and HR in treatment of CRLMs.

METHODS

A systematic search of PubMed, Embase, Cochrane Library and Web of Science up to October 1, 2020 was conducted for relevant studies that compared the prognosis of RFA with HR in the treatment of CRLMs. The primary outcomes were 30-day mortality, long-term recurrence, overall survival (OS) and disease-free survival (DFS). The secondary outcomes were various factors of OS, recurrence-free survival (RFS), survival, recurrence and complication.

RESULTS

A total of 22 studies including 4385 CRLM patients were identified. There was no significant difference between RFA and HR in 30-day mortality, with a pooled OR of 0.88 (95% CI 0.34-2.29; P = 0.80). CRLM patients undergoing RFA experienced significantly higher incidences of marginal and intrahepatic recurrence than HR, with pooled ORs of 7.09 (95% CI 4.56-11.2; 1251 pts) and 2.02 (95% CI 1.24-3.28; 1038 pts). In addition, RFA showed lower 1-, 3- and 5-yr OS rate than HR with pooled ORs of 0.39, 0.40 and 0.60 respectively. A lower 5-yr DFS rate was also found in RFA than HR group, with a pooled OR of 0.74 (95% CI 0.56-0.97; P = 0.03; 1231 pts). Multivariable analysis showed that tumor size, multiple tumors, age, primary node positive and metachronous metastasis were independent factors of OS, and multiple tumors was also an independent factor of RFS.

CONCLUSIONS

Though the 30-day mortality of RFA was equal to HR, RFA showed a higher recurrence rate and poor long-term survival outcomes for CRLM patients. Tumor size, multiple tumors, age, primary node positive and metachronous metastasis were independent factors of survival. However, the results were limited because of the inequality baseline characteristics between the comparative groups. Randomized or propensity score matching studies should be performed to clarify the effectiveness of RFA and to determine target populations that benefit most from RFA in the future.

Stereotactic radiofrequency ablation (SRFA) for recurrent colorectal liver metastases after hepatic resection

BACKGROUND

To evaluate the efficacy, safety and overall clinical outcome of multiprobe SRFA as a treatment for recurrent colorectal liver metastases after hepatic resection (HR).

METHODS

A retrospective, single center study carried out between 2006 and 2018. 64 consecutive patients with recurrent or new CRLM after previous HR were treated by SRFA for 217 lesions (median size 2.7 cm, 1-7.5) in 103 ablation sessions. Endpoints consisted of i) technical efficacy ii) complication and mortality rates iii) local and distant recurrence, iv) disease free survival (DFS), and v) overall survival (OS).

RESULTS

213/217 tumors were successfully ablated at initial SRFA (97.7% primary technical efficacy rate). Four tumors required repeat ablation, resulting in a secondary technical efficacy rate of 99.5% (216/217). Local recurrence developed in 25/217 lesions (11.5%). Major complication rate was 5.8% (6/103 sessions) and mortality rate was 1.0% (1/103 ablation sessions), respectively.1-, 3-, and 5- year OS rates from date of first SRFA were 90.1%, 46.2%, and 34.8% (median 33.1 months). DFS rates were 54.2%, 17.2%, and 17.2%, at 1-, 3- and 5- years, respectively (median 13.3 months).

CONCLUSION

SRFA is a safe, feasible and effective option for CRLM after HR with low morbidity levels and favorable clinical outcome.

The role of interventional oncology in the treatment of colorectal cancer liver metastases

Colorectal cancer is a leading cause of death both in Europe and worldwide. Unfortunately, 20-25% of patients with colorectal cancer already have metastases at the time of diagnosis, while 50-60% of the remainder will develop metastases later during the course of the disease. Although hepatic excision is the first-line treatment for patients with liver-limited colorectal metastases and is reported to prolong the survival of these patients, few patients are candidates. Locoregional therapy encompasses minimally invasive techniques practiced by interventional radiology. Most widely used locoregional therapies include ablative treatments (radiofrequency ablation, microwave ablation) and transcatheter intra-arterial therapies (transarterial chemoembolization, and radioembolization with yttrium-90).

The role of interventional oncology in the treatment of colorectal cancer liver metastases

Colorectal cancer is a leading cause of death both in Europe and worldwide. Unfortunately, 20-25% of patients with colorectal cancer already have metastases at the time of diagnosis, while 50-60% of the remainder will develop metastases later during the course of the disease. Although hepatic excision is the first-line treatment for patients with liver-limited colorectal metastases and is reported to prolong the survival of these patients, few patients are candidates. Locoregional therapy encompasses minimally invasive techniques practiced by interventional radiology. Most widely used locoregional therapies include ablative treatments (radiofrequency ablation, microwave ablation) and transcatheter intra-arterial therapies (transarterial chemoembolization, and radioembolization with yttrium-90).

Radiofrequency ablation versus resection for technically resectable colorectal liver metastasis: a propensity score analysis

BACKGROUND

Liver resection is the first-line treatment for patients with resectable colorectal liver metastasis (CRLM), while radiofrequency ablation (RFA) can be used for small unresectable CRLM because of disease extent, poor anatomical location, or comorbidities. However, the long-term outcomes are unclear for RFA treatment in resectable CRLM. This study aimed to compare the recurrence rates and prognosis between resectable CRLM patients receiving either liver resection or RFA.

METHODS

Consecutive patients who underwent RFA or hepatic resection from November 2010 to December 2015 were assigned in this retrospective study. Propensity score analysis was used to eliminate baseline differences between groups. Survival and recurrence rates were compared between patients receiving liver resection and RFA.

RESULTS

With 1:2 ratio of propensity scoring, 46 patients in the RFA group and 92 in the resection group were successfully matched. Overall survival was similar between the two groups, but the resection group had a higher disease-free survival (median, 22 months vs. 14 months). Whereas among patients with a tumor size of ≤ 3 cm, disease-free survival was similar in the two groups (median, 24 months vs. 21 months). Compared to the resection group, the RFA group had a higher rate of intrahepatic recurrence (34.8% vs. 12.0%) and a shorter recurrence free period. The local and systemic recurrence rate and recurrence-free period for the same were insignificant in the two groups. Poor disease-free survival was associated with RFA, T4, tumor diameter > 3 cm, and lymph node positivity.

CONCLUSION

Among patients with technically resectable CRLM, resection provided greater disease-free survival, although both treatment modalities provided similar overall survival.

Stereotactic body radiotherapy for lung metastases from colorectal cancer: a single institution experience

Aim: Stereotactic body radiotherapy (SBRT) has been used as an alternative to surgical intervention to treat primary malignanices of the lung as well as lesions from other primaries. In this study, we evaluate the safety and efficacy of SBRT in treating lung metastases from colorectal cancer (CRC). Materials & methods: We reviewed 22 patients that underwent lung SBRT for metastases from CRC. Almost all patients received chemotherapy before and after undergoing SBRT. Outcomes that were analyzed included overall survival, distant failure and progression-free survival, as well as the effects of biologically effective dose (BED) and KRAS status on local control. Results: Seven females and 15 males underwent SBRT to lung metastases from CRC. The median Eastern Cooperative Oncology Group status was one (0–2). The median dose was 48 Gy (40–54 Gy) in 5 fx (4–8 fx) and the median number of nodules treated with SBRT was one (1–3). Median follow-up was 28.5 months from SBRT and 79 months (9–145) from primary diagnosis. Local control at 1 and 3 years was 75 and 58%, respectively. There was a trend toward improved local control with increasing biologically effective dose (BED10 > 100; p = 0.07). Cancers that were positive for the KRAS mutation had increased local control at 12 months, 100 versus 75% (p = 0.0199). Median OS from the primary diagnosis of CRC and from SBRT was 79 and 31 months, respectively. There were no predictors for OS. There were no episodes of acute or late grade 3 or higher toxicity. Conclusion: The results of this study add to the growing body of literature to support SBRT for lung metastases, specifically those patients with limited lung metastases from CRC. The choice of radiation dose remains important, even in metastatic disease, as highlighted by the trend toward improved local control with increasing BED10.

Factors influencing survival of patients with pancreatic adenocarcinoma and synchronous liver metastases receiving palliative care

BACKGROUND AND AIMS

Patients with pancreatic ductal adenocarcinoma and synchronous liver metastases (PACLM) have an extremely limited life expectancy. We performed a single-center analysis to explore the clinical results and prognostic factors of patients with PACLM receiving palliative care.

METHODS

We retrospectively reviewed 189 patients undergoing palliative care at Tianjin Medical University Cancer Hospital over a 15-year period. Clinical characteristics, survival condition, and factors associated with survival were analyzed. Treatment methods included palliative bypass surgery, percutaneous transhepatic cholangiodrainage, drug analgesia, symptomatic treatment, and other nutritional or supportive measures.

RESULTS

The overall survival (OS) was 3.6 months for all patients. Multivariate analysis for clinical features showed that Karnofsky performance score (KPS), ascites, cigarette smoking, primary tumor size, and lactate dehydrogenase (LDH) were prognostic variables with statistical significance (P < 0.05). The patients were classified into three groups of patients according to how many of these 5 risk factors were present: 0-1, 2, or 3-5 risk factors. The median OS of the 3 groups of patients were 5.0, 3.3, and 2.5 months, respectively, with a notable statistical significance (P < 0.0001).

CONCLUSIONS

KPS<80, ascites, cigarette smoking, primary tumor size≥5 cm, and LDH≥250U/L are effective predictive factors of poor prognosis for patients with PACLM. The stratification of treatment outcome groups based on these factors facilitates evaluation of individual prognosis and can guide clinical decisions.

Local tumor progression patterns after radiofrequency ablation of colorectal cancer liver metastases

PURPOSE

We aimed to evaluate patterns of local tumor progression (LTP) after radiofrequency ablation (RF ablation) of colorectal cancer liver metastases (CRCLM) and to highlight the percentage of LTP not attributable to lesion size or RF ablation procedure-related factors (heat sink or insufficient ablation margin).

METHODS

CRCLM treated by RF ablation at a single tertiary care center from 2004-2012, with a minimum of six months of postprocedure follow-up, were included in this retrospective study. LTP morphology was classified as focal nodular (<90° of ablation margin), circumferential (>270°), or crescentic (90°-270°). Initial metastasis size, minimum ablation margin size, morphology of LTP, presence of a heat sink, and time to progression were recorded independently by two radiologists.

RESULTS

Thirty-two of 127 RF ablation treated metastases (25%) with a mean size of 23 mm (standard deviation 12 mm) exhibited LTP. Fifteen of 32 LTPs (47%) were classified as focal nodular, with seven having no procedure-related factor to explain recurrence. Ten of 32 LTPs (31%) were circumferential, with four having no procedure-related factor to explain recurrence. Seven of 32 LTPs (22%) were crescentic, with two having no procedure-related factor to explain recurrence. Of the 13 lesions without any obvious procedure-related reason for LTP, six (46%) were <3 cm in size.

CONCLUSION

Although LTP in RF ablation treated CRCLM can often be explained by procedure-related factors or size of the lesion, in this study up to six (5%) of the CRCLM we treated showed LTP without any reasonable cause.

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.

Clinical practice guidelines for the management of metastatic colorectal cancer: a consensus statement of the Hellenic Society of Medical Oncologists (HeSMO)

There is discrepancy and failure to adhere to current international guidelines for the management of metastatic colorectal cancer (CRC) in hospitals in Greece and Cyprus. The aim of the present document is to provide a consensus on the multidisciplinary management of metastastic CRC, considering both special characteristics of our Healthcare System and international guidelines. Following discussion and online communication among the members of an executive team chosen by the Hellenic Society of Medical Oncology (HeSMO), a consensus for metastastic CRC disease was developed. Statements were subjected to the Delphi methodology on two voting rounds by invited multidisciplinary international experts on CRC. Statements reaching level of agreement by ≥80% were considered as having achieved large consensus, whereas statements reaching 60-80% moderate consensus. One hundred and nine statements were developed. Ninety experts voted for those statements. The median rate of abstain per statement was 18.5% (range: 0-54%). In the end of the process, all statements achieved a large consensus. The importance of centralization, care by a multidisciplinary team, adherence to guidelines, and personalization is emphasized. R0 resection is the only intervention that may offer substantial improvement in the oncological outcomes.

Percutaneous cryoablation of hepatic tumors: long-term experience of a large U.S. series

PURPOSE

To report our long-term experience with percutaneous cryotherapy for primary and metastatic liver tumors, including historical perspectives on complications over time and local recurrence rates.

MATERIALS AND METHODS

Following IRB approval under HIPAA compliance, 342 CT fluoroscopic-guided, percutaneous cryotherapy procedures were performed for 443 masses in 212 outpatients with hepatocellular carcinoma (HCC; N = 36), or metastatic disease (N = 176), grouped as colorectal carcinoma (CRC) and non-CRC metastases. Tumor and ablation sizes were noted in relation to adjacent vasculature. All complications were graded according to standardized criteria. Patients were followed by CT and/or MRI at 1, 3, 6, 12, 18, 24 months and yearly thereafter. Local recurrences were defined as either "procedural" within the ice ablation zone, or "satellite" within 1 cm of the ablation rim to evaluate recurrence patterns.

RESULTS

Average tumor diameter of 2.8 cm was treated by average cryoprobe number of 4.5, which produced CT-visible ice ablation zone diameters averaging 5.2 cm. Grade >3 complications were primarily hematologic [N = 20/342; (5.8%)], and appeared related to pre-procedural anemia/thrombocytopenia, carcinoid tumor type, and large ablation volumes. No significant central biliary leak, strictures, or bilomas were noted. At a mean follow-up of 1.8 years, local tumor recurrences were 5.5%, 11.1%, and 9.4% for HCC, CRC, and non-CRC metastases, respectively, consisting mainly of satellite foci. No significant difference was noted for local recurrences near major blood vessels or tumors >3 cm diameter.

CONCLUSIONS

Percutaneous hepatic cryotherapy is a well-visualized, safe procedure that produces very low local recurrence rates, even for tumors near vasculature and diameters over 3 cm. Cryoablation deserves to be in the armamentarium of percutaneous hepatic ablation, especially with careful patient selection for tumors <4 cm and patients with platelet counts >100,000. Percutaneous hepatic cryoablation represents a highly flexible technique with particular benefits near central biliary structures and/or adjacent crucial structures.

Evidence-based medical oncology and interventional radiology paradigms for liver-dominant colorectal cancer metastases

Colorectal cancer metastasizes predictably, with liver predominance in most cases. Because liver involvement has been shown to be a major determinant of survival in this population, liver-directed therapies are increasingly considered even in cases where there is (limited) extrahepatic disease. Unfortunately, these patients carry a known risk of recurrence in the liver regardless of initial therapy choice. Therefore, there is a demand for minimally invasive, non-surgical, personalized cancer treatments to preserve quality of life in the induction, consolidation, and maintenance phases of cancer therapy. This report aims to review evidence-based conceptual, pharmacological, and technological paradigm shifts in parenteral and percutaneous treatment strategies as well as forthcoming evidence regarding next-generation systemic, locoregional, and local treatment approaches for this patient population.

Ablation therapy of hepatocellular carcinoma: a comparative study between radiofrequency and microwave ablation

PURPOSE

The aim of the study is to retrospectively evaluate and compare the therapeutic response of Radiofrequency (RF) and Microwave (MW) ablation therapy of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

53 consecutive patients (42 males, 11 females; mean age 59 years, range: 40-68, SD: 4.2) underwent CT-guided percutaneous RF and MW ablation of 68 HCC liver lesions. The morphologic tumor response (number, location and size) was evaluated by magnetic resonance imaging. The follow-up protocol was 24 h post-ablation then within 3 monthly intervals post-ablation in the first year and 6 monthly intervals thereafter.

RESULTS

Complete therapeutic response was noted in 84.4% (27/32) of lesions treated with RFA and in 88.9% (32/36) of lesions treated with MW ablation (P = 0.6). Complete response was achieved in all lesions ≤2.0 cm in diameter in both groups. There was no significant difference in rates of residual foci of HCC lesions between RF and MW ablation groups (P = 0.15, Log-rank test). Recurrence rate for 3, 6, 9, and 12 months in patients with HCC who underwent RF ablation compared with MW ablation were 6.3%, 3.1%, 3.1% versus 0%, 5.6%, 2.8%, and 2.8%. Progression-Free Survival rates for treated patients with RF ablation of 1, 2, and 3 years were 96.9%, 93.8%, and 90.6% and treated with MW ablation therapy were 97.2%, 94.5%, and 91.7, respectively (P = 0.98).

CONCLUSION

In conclusion, RF and MW ablation therapy showed no significant difference in the treatment of HCC regarding the complete response, rates of residual foci of untreated disease, and recurrence rate.

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.

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.

Non-operative therapies for colorectal liver metastases

Locoregional therapies for colorectal liver metastases complement systemic therapy by providing an opportunity for local control of hepatic spread. The armamentarium for liver-directed therapy includes ablative therapies, embolization, and stereotactic body radiation therapy. At this time, prospective studies comparing these modalities are limited and decision-making relies on a multidisciplinary approach for optimal patient management. Herein, we describe multiple therapeutic non-surgical procedures and an overview of the results of these treatments.

Complications after percutaneous ablation of liver tumors: a systematic review

BACKGROUND

Although ablation therapy has been accepted as a promising and safe technique for treatment of unrespectable hepatic tumors, investigation of its complications has been limited. A physician who performs ablation treatment of hepatic malignancies should be aware of the broad spectrum of complications. Proper management is possible only if the physician Performing ablation understands the broad spectrum of complications encountered after ablation.

OBJECTIVES

TO SYSTEMATICALLY REVIEW THE COMPLICATIONS AFTER DIFFERENT ABLATION MODALITIES: Radiofrequency ablation (RFA), microwave ablation (MWA) and Nano knife for the treatment of liver tumors and analyze possible risk factors that precipitate these complications.

SEARCH METHODS

WE PERFORMED ELECTRONIC SEARCHES IN THE FOLLOWING DATABASES: MEDLINE, EMBASE and COCHARNE. Current trials were identified through the Internet (from January 1, 2000 to January 1, 2014). We included only studies who specific mentioned complications after liver ablation therapy (RFA/MWA/Nano knife).

MAIN RESULTS

A total of 2,588 publications were identified, after detailed examination only 32 publications were included in the review. The included studies involved 15,744 participants. According to the type of technique, 13,044 and 2,700 patients were included for RFA and MWA. Analysis showed a pooled mortality of 0.15% for RFA, and 0.23% for MWA.

CONCLUSIONS

This systematic review gathers information from controlled clinical trials and observational studies which are vulnerable to different types of bias, never the less RFA and MWA can be considered safe techniques for the treatment of liver tumors.

"How we do it" - a practical approach to hepatic metastases ablation techniques

Secondary liver malignancies are associated with significant mortality and morbidity if left untreated. Colorectal cancer is the most frequent origin of hepatic metastases. A multidisciplinary approach to the treatment of hepatic metastases includes medical, surgical, radiation and interventional oncology. The role of interventional oncology in the management of hepatic malignancies continues to evolve and applies to a large and continuous spectrum of metastatic disease, from the relatively small solitary metastasis to larger tumors and multifocal liver disease. Within the past 10 years, several publications of percutaneous image-guided ablation indicated the effectiveness and safety of this minimally invasive therapy for selected patients with limited number (arguably up to 4 metastases) of relatively small (less than 5cm) hepatic metastases. Different image-guided procedures such radiofrequency, microwave, and laser cause thermal ablation and coagulation necrosis or cell death of the target tumor. Cryoablation, causing cell death via cellular freezing, has also been used. Recently, irreversible electroporation, a nonthermal modality, has also been used for liver tumor ablation. In the following section, we review the different liver ablation techniques, as well as indications for ablation, specific patient preparations, and different "tricks of the trade" that we use to achieve safe and effective liver tumor ablation. We also discuss appropriate imaging and clinical patient follow-up and potential complications of liver tumor ablation.

Surgical resection for local recurrence after radiofrequency ablation for colorectal liver metastasis is more extensive than primary resection

OBJECTIVE

As a minimally invasive modality, radiofrequency ablation (RFA) has been increasingly applied not only for the treatment of hepatocellular carcinoma, but also for that of colorectal liver metastasis (CLM). However, RFA for CLM has been shown to be associated with a high local recurrence rate, and no optimal treatment for RFA failure has been established yet. The aim of this study was to evaluate the feasibility and outcome of surgical resection for local recurrence after RFA.

MATERIAL AND METHODS

A retrospective study of 17 patients, who underwent surgery for local recurrence after RFA for resectable CLM, was carried out. The surgical procedures involved in the actual surgery were compared with those envisioned for the primary resection if RFA had not been selected.

RESULTS

Surgical resection for RFA recurrence was more invasive than the envisioned surgical procedure in 10 cases (58%). In addition, the proportions of cases that required technically demanding procedures among the patients receiving surgery for RFA recurrence were higher than those in envisioned operations; major hepatectomy, eight cases [47%] versus two cases [12%] (p<0.0205); excision and/or reconstruction of the major hepatic veins, three cases [18%] versus zero case [0%] (p=0.035); excision of diaphragm: three cases [18%] versus zero case [0%] (p=0.035). The 1-, 3- and 5-year overall survival rates were 92%, 45% and 45%, respectively.

CONCLUSIONS

Surgical resection for RFA recurrence for CLM required more invasive and technically demanding procedures. Thus, RFA for CLM should be limited to unresectable cases, and patients with resectable CLM should be thoroughly advised not to undergo RFA, but rather surgical resection.

Ablation for hepatocellular carcinoma: validating the 3-cm breakpoint

BACKGROUND

Although many previous studies on local ablation outcomes for hepatocellular carcinoma (HCC) have dichotomized tumor size with a 3-cm cutoff to determine prognostic significance, a growing number of reports describe excellent outcomes for larger tumors. To address the logic of this 3-cm cutoff beyond small single-center experiences, we stratified patients by 1-cm tumor size intervals and hypothesized that disease-specific survival (DSS) would not vary significantly between adjacent groups.

METHODS

Patients treated with local ablation for T1 HCC (≤8 cm) were identified from the surveillance, epidemiology, and end results database (2004-2008). Log-rank tests and multivariable Cox proportional hazards models were used to compare DSS curves of adjacent study groups.

RESULTS

There were 1,083 patients included in the study (26 % female, median age: 62 years). The 3-year DSS was significantly lower in patients with 3- to 4-cm tumors compared to 2- to 3-cm tumors (58 vs. 72 %, p = 0.002). In adjusted models, DSS did not vary significantly between any size intervals up to 3 cm. Patients with 3- to 4-cm tumors, however, had a poorer prognosis compared with patients with 2- to 3-cm tumors (hazard ratio: 1.6, 95 % confidence interval: 1.18-2.18, p = 0.002). DSS also fell when tumor size increased from 5-6 to 6-7 cm (53 vs. 21 %, 0.006).

CONCLUSIONS

This study emphasizes the 3-cm size, and possibly the 6-cm size, as informative predictive thresholds when ablating HCC, because variability of DSS occurred specifically at these tumor sizes. Future research in this field should either adopt a 3-cm breakpoint or provide evidence for alternative thresholds.

Current oncologic applications of radiofrequency ablation therapies

Radiofrequency ablation (RFA) uses high frequency alternating current to heat a volume of tissue around a needle electrode to induce focal coagulative necrosis with minimal injury to surrounding tissues. RFA can be performed via an open, laparoscopic, or image guided percutaneous approach and be performed under general or local anesthesia. Advances in delivery mechanisms, electrode designs, and higher power generators have increased the maximum volume that can be ablated, while maximizing oncological outcomes. In general, RFA is used to control local tumor growth, prevent recurrence, palliate symptoms, and improve survival in a subset of patients that are not candidates for surgical resection. It’s equivalence to surgical resection has yet to be proven in large randomized control trials. Currently, the use of RFA has been well described as a primary or adjuvant treatment modality of limited but unresectable hepatocellular carcinoma, liver metastasis, especially colorectal cancer metastases, primary lung tumors, renal cell carcinoma, boney metastasis and osteoid osteomas. The role of RFA in the primary treatment of early stage breast cancer is still evolving. This review will discuss the general features of RFA and outline its role in commonly encountered solid tumors.

Predictive value of apparent diffusion coefficient in evaluation of colorectal carcinoma hepatic metastases' response to radiofrequency ablation

PURPOSE

To establish the apparent diffusion coefficient (ADC) suitability to evaluate the radiofrequency ablation (RFA) outcome in patients with chemotherapy resistant or partially responding colorectal adenocarcinoma liver metastases.

MATERIALS AND METHODS

A total of 56 patients with 116 metastatic foci over 10 mm in diameter were examined with 1.5 Tesla MRI scanner 1 day before percutaneous RFA treatment. Lesions were evaluated in echo-planar diffusion-weighted images with b = 0, 15 and 500 s/mm(2) . On basis of computed tomography scan at 6 weeks, 3 and 6 months after RFA and serum CEA (carcinoembryonic antigen) level lesion were recognized as responding or nonresponding lesions. ADC values for b = 0-15 and 0-500 s/mm(2) of responding and nonresponding lesions were compared.

RESULTS

Noncomplete ablation concerned 28 lesions. Mean pretreatment ADC values for b = 0-15 and 0-500 s/mm(2) of responding metastases were significantly lower (2.14 and 1.48 × 10(-3) mm(2) /s) than those of nonresponding tumors (2.7 and 1.74 × 10(-3) mm(2) /s). Sensitivity, specificity, and accuracy of ADC values for b = 0-15 s/mm(2) were 79 (95%CI = 59-92), 85 (95%CI = 76-92), 84%; and for b = 0-500 s/mm(2) , the efficacy parameters were, respectively, 78 (95%CI = 56-92), 78 (95%CI = 67-86), and 78%. The P value was under 0.001 for both b parameters.

CONCLUSION

The pretreatment ADCs values of chemotherapy resistant or partially responding colorectal adenocarcinoma liver metastatic lesion can be predictive factor of tumors response to RFA therapy.

Treatment of pulmonary colorectal metastases by radiofrequency ablation

We evaluated the local tumor control and the survival benefit achieved with radiofrequency ablation (RFA) for nonoperable lung metastases in 45 patients with colorectal cancer. Median survival from the time of RFA was 46 months. One-, 2- and 3-year local tumor progression (LTP)-free survival rates were 92%, 77%, and 77%, respectively. RFA offers very good local control in patients with pulmonary metastases from colorectal cancer.

BACKGROUND

Radiofrequency ablation has emerged as a potential, lung function-preserving treatment of colorectal lung metastases.

PATIENTS AND METHODS

Forty-five patients with colorectal pulmonary metastases underwent computed tomography-guided RFA from December 2004 to June 2010. A baseline posttreatment scan was obtained 4-6 weeks after RFA and follow-up imaging studies every 3 months thereafter were obtained and compared to evaluate the tumor progression at site of ablation or elsewhere. The primary end points were LTP-free survival and overall survival from RFA procedure. The Kaplan-Meier method was used to analyze the end points. A Cox proportional hazard model with robust inference was used to estimate the associations between baseline factors and survival end points.

RESULTS

Sixty-nine metastases were ablated in 45 patients. Tumor size ranged from 0.4 to 3.5 cm. The median number of metastases ablated per patient was 1 (range, 1-3). Median follow-up after RFA was 18 months. Median survival from the time of RFA was 46 months (95% confidence interval [CI], 27.8-47.3). One-, 2- and 3-year overall survival rates from the time of RFA were 95% (95% CI, 82%-99%), 72% (95% CI, 52%-85%), and 50% (95% CI, 26%-71%), respectively. Nine of 69 lesions (13%) progressed and 4 were retreated with no progression after second RFA. Median time to progression was not reached. LTP-free survival from RFA was 92% (95% CI, 82%-97%) at 1 year, 77% (95% CI, 58%-88%) at 2 years, and 77% (95% CI, 58%-88%) at 3 years.

CONCLUSION

Radiofrequency ablation of lung metastases is an effective minimally invasive, parenchymal-sparing technique that has very good local control rates in patients with pulmonary metastases from colorectal cancer, with LTP-free survival of 77% at 3 years.

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.

[Abscesso-colonic fistula following radiofrequency ablation therapy for hepatocellular carcinoma; a case successfully treated with histoacryl embolization]

Hepatocellular carcinoma (HCC) is one of the most common malignant neoplasms occuring worldwide. Although surgical resection still remains the treatment of choice for HCC, radiofrequency ablation (RFA) has emerged as reliable alternatives to resection. It is less invasive and can be repeated after short intervals for sequential ablation in case of multiple lesions. The most common complication of RFA is liver abscess, and bile duct injury such as bile duct stricture has been reported. This is a case report of a rare complication of abscesso-colonic fistula after RFA for HCC. The case was treated by percutaneous abscess drainage and antibiotics and occlusion of abscesso-colonic fistula with n-butyl-2-cyanoacrylate embolization.

The current role of minimally invasive therapies in the management of liver tumors

This is a review of minimally invasive therapy options for liver tumors, such as highly focused ultrasound, microwave ablation, and irreversible electroporation, as well as new aspects of radiofrequency ablation. Radiofrequency ablation is recommended for patients with early-stage HCC with up to 3 lesions with a tumor diameter within 3 cm and for patients with non-resectable liver metastasis. Indications and contraindications to treatment are designated, and different modalities for image-based therapy guidance are compared. Options for therapy monitoring and controlling are reviewed, namely intraprocedural tools, imaging and functional parameters and their evolution during therapy. Prevention and control of local recurrences is discussed. We also present a short review of current clinical results in treating liver metastasis and primary liver tumors.

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.

Multi-modality treatment of colorectal liver metastases

Liver metastases synchronously or metachronously occur in approximately 50% of colorectal cancer patients. Multimodality comprehensive treatment is the best therapeutic strategy for these patients. However, the optimal pattern of multimodality therapy is still controversial, and it raises several significant concerns. Liver resection is the most important treatment for colorectal liver metastases. The definition of resectability has shifted to focus on the completion of R0 resection and normal liver function maintenance. The role of neoadjuvant and adjuvant chemotherapy still needs to be clarified. The management of either progression or complete remission during neoadjuvant chemotherapy is challenging. The optimal sequencing of surgery and chemotherapy in synchronous colorectal liver metastases patients is still unclear. Conversional chemotherapy, portal vein embolization, two-stage resection, and tumor ablation are effective approaches to improve resectability for initially unresectable patients. Several technical issues and concerns related to these methods need to be further explored. For patients with definitely unresectable liver disease, the necessity of resecting the primary tumor is still debatable, and evaluating and predicting the efficacy of targeted therapy deserve further investigation. This review discusses different patterns and important concerns of multidisciplinary treatment of colorectal liver metastases.

Lack of Anatomical Concordance between Preablation and Postablation CT Images: A Risk Factor Related to Ablation Site Recurrence

Objective. Variation in the position of the liver between preablation and postablation CT images hampers assessment of treatment of colorectal liver metastasis (CRLM). The aim of this study was to test the hypothesis that discordant preablation and postablation imaging is associated with more ablation site recurrences (ASRs). Methods. Patients with CRLM were included. Index-tumor size, location, number, RFA approachs and ablative margins were obtained on CT scans. Preablation and postablation CT images were assigned a "Similarity of Positioning Score" (SiPS). A suitable cutoff was determined. Images were classified as identical (SiPS-id) or nonidentical (SiPS-diff). ASR was identified prospectively on follow-up imaging. Results. Forty-seven patients with 97 tumors underwent 64 RFA procedures (39 patients/63 tumors open RFA, 25 patients/34 tumours CT-targeted RFA, 12 patients underwent >1 RFA). Images of 52 (54%) ablation sites were classified as SiPS-id, 45 (46%) as SiPS-diff. Index-tumor size, tumor location and number, concomitant partial hepatectomy, and RFA approach did not influence the SiPS. ASR developed in 11/47 (23%) patients and 20/97 (21%) tumours. ASR occurred less frequently after open RFA than after CT targeted RFA (P < 0.001). ASR was associated with larger index-tumour size (18.9 versus 12.8 mm, P = 0.011). Cox proportional hazard model confirmed SiPS-diff, index-tumour size >20 mm and CT-targeted RFA as independent risk factors for ASR. Conclusion. Variation in anatomical concordance between preablation and postablation images, index-tumor size, and a CT-targeted approach are risk factors for ASR in CRLM.

Percutaneous stereotactic radiofrequency ablation of colorectal liver metastases

OBJECTIVES

To evaluate the outcome of patients with colorectal liver metastasis (CRLM) treated with stereotactic radiofrequency ablation (SRFA).

METHODS

Following IRB approval, a retrospective evaluation of 98 SRFA treatment sessions of 189 CRLMs in 63 consecutive patients was performed. Local recurrence rate (LR), overall survival (OS) and disease-free survival (DFS) were analysed.

RESULTS

LR was identified in 16% of the tumours (31/189), with no significant differences (P = 0.635) when comparing tumour sizes <3 cm (17.7%), 3-5 cm (11.1%) and >5 cm (17.4%). The median OS from SRFA treatment was 33.2 months after a mean follow-up of 25 months (range 2-66); the corresponding 1-, 3- and 5- year survival rates were 87%, 44% and 27%. The median OS was significantly different when comparing unresectable and resectable patients (27 vs. 58 months, P = 0.002) with OS rates of 92%, 66% and 48% at 1, 3 and 5 years in resectable patients. Tumour size did not affect OS and DFS.

CONCLUSION

Due to the favourable outcome, SRFA challenges resection as first-line local treatment of patients with CRLM. As long as randomised studies are pending, we recommend entering an individual decision-making process with every patient.

KEY POINTS

Large colorectal liver metastases can be effectively treated by stereotactic radiofrequency ablation (SRFA). Using SRFA the overall survival is not affected by tumour size. SRFA achieves similar overall and disease-free survival rates as surgical resection. SRFA challenges surgical resection as the first-line treatment for colorectal liver metastases.

Ablative therapies for colorectal liver metastases: a systematic review

AIM

The standard treatment for colorectal liver metastases (CRLM) is surgical resection. Only 20-30% of patients are deemed suitable for surgery. Recently, much attention has focused on ablative therapies either to treat unresectable CRLM or to extend the margins of resectability. This review aims to assess the long-term outcome and complication rates of various ablative therapies used in the management of CRLM.

METHOD

A literature search was performed of electronic databases including Medline, Cochrane Collaboration Library and the National Library of Medicine's ClinicalTrials.gov. Inclusion criteria were ablation for CRLM with minimum 1 year follow-up and >10 patients, published between January 1994 and January 2010.

RESULTS

In all, 226 potentially relevant studies were identified, of which 75 met the inclusion criteria. Cryotherapy (26 studies) had local recurrence rates of 12-39%, with mean 1-, 3- and 5-year survival rates of 84%, 37% and 17%. The major complication rate ranged from 7% to 66%. Microwave ablation (13 studies) had a local recurrence rate of 5-13%, with a mean 1-, 3- and 5-year survival of 73%, 30% and 16%, and a major complication rate ranging from 3% to 16%. Radiofrequency ablation (36 studies) had a local recurrence rate of 10-31%, with a mean 1-, 3- and 5-year survival of 85%, 36% and 24%, with major complication rate ranging from 0% to 33%.

CONCLUSION

Ablative therapies offer significantly improved survival compared with palliative chemotherapy alone with 5-year survival rates of 17-24%. Complication rates amongst commonly used techniques are low.

In vivo evaluation of a MR-guided 980nm laser interstitial thermal therapy system for ablations in porcine liver

PURPOSE

To evaluate the use of a 980-nm diode laser for magnetic resonance-guided laser interstitial thermal therapy (MR-guided LITT) ablations in liver tissue in an in vivo porcine model.

MATERIALS AND METHODS

MR-guided guided LITT was performed on nine juvenile pigs placed under general anesthesia. Target ablation sites were selected in the left and right lobes of the liver. Laser applicators were placed in the liver using intermittent MR guidance. Up to four separate ablations were performed in each animal using a 15 or 30 W laser generator using one or two applicators. During the ablations, continuous MR-based temperature mapping (MR-thermal mapping), using a proton resonance frequency technique, was performed to monitor the size of the ablation in real-time. Extent of thermal tissue damage was continuously estimated based on Arrhenius model. Two-minute ablations were performed at each site. MR-thermal mapping of ablations within the posteroinferior liver were accomplished with continuous breathing at low tidal volume. In the mid right lobe of the liver, due to motion artefacts, MR-thermometry was performed intermittently during breath hold periods. In the left lobe of the liver, ablations were performed with ventilation using positive end expiratory pressure (PEEP) of 10 cm of water. Upon completion, MR imaging with gadolinium contrast was performed to assess the extent of treatment. Thermal lesions were subsequently measured using both, MR-thermal dose and MR gadolinium images, for comparison. Following the animal euthanasia, the liver was harvested and subjected to formalin fixation and paraffin embedding for histological examination.

RESULTS

Between one and four focal liver ablations (total 24 ablations) were successfully performed in nine animals with either a 15 or 30 W laser generator. For the 15-W laser generator, the average single applicator ablation size was (2.0 ± 0.5) × (2.6 ± 0.4) cm(2) , as measured by magnetic resonance (MR) thermometry, or (1.7 ± 0.4) × (2.2 ± 0.6) cm(2) , as measured with gadolinium contrast, with the difference being not statistically significant. For the 30-W laser generator, the average single applicator ablation size was (2.4 ± 0.3) × (3.3 ± 0.5) cm(2) by MR thermometry and (2.1 ± 0.4) × (2.9 ± 0.3) cm(2) by gadolinium enhancement, with no statistically significant difference. Simultaneously activating two applicators with the 15 W generator demonstrated ablation sizes of (3.7 ± 0.9) × (3.2 ± 0.1) cm(2) using MR thermometry and (2.3 ± 0.6) × (2.4 ± 0.3) cm(2) with gadolinium contrast, while using two applicators in the 30-W laser generator, yielded (4.5 ± 0.6) × (3.9 ± 0.2) cm(2) using MR thermometry and (4.4 ± 1.1) × (3.6 ± 0.5) cm(2) with gadolinium contrast enhancement.

CONCLUSION

In our experience, we found that liver ablations performed with a MR-guided 980-nm diode LITT system through the saline cooled catheter applicator could be performed throughout the liver. Additionally, liver ablations were safe and produced a clinically applicable ablation zone. These results suggest the 980-nm diode laser MR-guided LITT system could be effective in treatments of hepatic tumors.

Mortality and complication rates of percutaneous ablative techniques for the treatment of liver tumors: a systematic review

OBJECTIVES

Reported rates of major complications and mortality of radiofrequency ablation (RFA), microwave ablation (MWA) and percutaneous ethanol injection (PEI) for the treatment of liver tumours were substantially heterogeneous among studies. The aim was to analyse the mortality and major complication rates of percutaneous RFA, PEI and MWA.

METHODS

MEDLINE and EMBASE search from January 1982 to August 2010. Randomised clinical trials and observational studies, age >18, more than 50 patients for each technique analysed, studies reporting mortality and major complications were included. Random effects model was performed, with assessment for heterogeneity and publication bias.

RESULTS

Thirty-four studies including 9531, 1185, and 1442 patients for RFA, MWA, and PEI, respectively were included. For all ablative techniques pooled proportion mortality rate was 0.16% (95% confidence interval [CI], 0.10-0.24). Pooled mortality rate associated with RFA, PEI and MWA was 0.15% (0.08-0.23), 0.59% (0.14-1.3) and 0.23% (0.0-0.58) respectively. Pooled proportion of major complications was 3.29% (2.43-4.28). Major complication rates associated with RFA, MWA, and PEI was 4.1% (3.3-5.1), 4.6% (0.7-11.8) and 2.7% (0.28-7.4) respectively.

CONCLUSIONS

Percutaneous RFA, PEI and MWA can be considered safe techniques for the treatment of liver tumours.

Image-based monitoring of magnetic resonance-guided thermoablative therapies for liver tumors

Minimally invasive treatment options for liver tumor therapy have been increasingly used during the last decade because their benefit has been proven for primary and inoperable secondary liver tumors. Among these, radiofrequency ablation has gained widespread consideration. Optimal image-guidance offers precise anatomical information, helps to position interventional devices, and allows for differentiation between already-treated and remaining tumor tissue. Patient safety and complete ablation of the entire tumor are the overriding objectives of tumor ablation. These may be achieved most elegantly with magnetic resonance (MR)-guided therapy, where monitoring can be performed based on precise soft-tissue imaging and additional components, such as diffusion-weighted imaging and temperature mapping. New MR scanner types and newly developed sequence techniques have enabled MR-guided intervention to move beyond the experimental phase. This article reviews the current role of MR imaging in guiding radiofrequency ablation. Signal characteristics of primary and secondary liver tumors are identified, and signal alteration during therapy is described. Diffusion-weighted imaging (DWI) and temperature mapping as special components of MR therapy monitoring are introduced. Practical information concerning coils, sequence selection, and parameters, as well as sequence gating, is given. In addition, sources of artifacts are identified and techniques to decrease them are introduced, and the characteristic signs of residual tumor in T1-, T2-, and DWI are described. We hope to enable the reader to choose MR sequences that allow optimal therapy monitoring depending on the initial signal characteristics of the tumor as well as its size and location in the liver.

Percutaneous radiofrequency thermal ablation of primary and metastatic hepatic tumors: current concepts and review of the literature

The liver is a common site for primary malignancy and hematogenous metastasis. Although surgical resection of primary or metastatic hepatic tumors is generally regarded as first-line therapy, the majority of patients with hepatic malignancy have disease that is not amenable to surgical resection because of tumor location, poor hepatic reserve, or medical comorbidities. This has led to significant interest in the development of nonsurgical image-guided therapies, including radiofrequency ablation (RFA). RFA is appealing as a minimally invasive therapy that may be performed on an outpatient basis. It enables ablation of an area 3 to 5 cm in diameter, with relatively low morbidity and mortality rates. The results concerning the use of percutaneous RFA in the treatment of hepatocellular carcinoma, colorectal metastases, and other hepatic metastases are reviewed in this article. Clinical and technical considerations and complications are also discussed.

Volumetric arterial enhancement fraction predicts tumor recurrence after hepatic radiofrequency ablation of liver metastases: initial results

OBJECTIVE

The objective of our study was to investigate the diagnostic value of the volumetric arterial enhancement fraction of the liver with color mapping for the early detection of tumor relapse after hepatic radiofrequency ablation (RFA).

MATERIALS AND METHODS

Fifty-three patients (24 men, 29 women; mean age ± SD, 65 ± 10 years) with a total of 215 liver metastases treated by RFA and a mean postinterventional follow-up period of 20 ± 15 (SD) months were included in this retrospective study. Quantitative arterial enhancement fraction color maps of the whole liver were computed from triple-phase contrast-enhanced MDCT images. Follow-up examinations served as the standard of reference. The diagnostic performance of the arterial enhancement fraction color maps to predict subsequent tumor occurrence before tumor was visible on routine multiphase CT images was evaluated.

RESULTS

The mean arterial enhancement fraction of segments that developed metastases (62% ± 23%) was significantly higher than the mean of segments that did not develop metastases (39% ± 20%) (p < 0.0001). Receiver operating characteristic curve analysis revealed a probability of 77% for arterial enhancement fraction values to be higher in case of subsequent metastases as compared with liver parenchyma without tumor recurrence.

CONCLUSION

The arterial enhancement fraction provides incremental value in the imaging surveillance for liver metastases after RFA. Arterial enhancement fraction color maps may be suited to predict tumor recurrence earlier than routine assessment using contrast-enhanced MDCT.

Viable tumor tissue adherent to needle applicators after local ablation: a risk factor for local tumor progression

Background

Local tumor progression (LTP) is a serious complication after local ablation of malignant liver tumors, negatively influencing patient survival. LTP may be the result of incomplete ablation of the treated tumor. In this study, we determined whether viable tumor cells attached to the needle applicator after ablation was associated with LTP and disease-free survival.

Methods

In this prospective study, tissue was collected of 96 consecutive patients who underwent local liver ablations for 130 liver malignancies. Cells and tissue attached to the needle applicators were analyzed for viability using glucose-6-phosphate-dehydrogenase staining and autofluorescence intensity levels of H&E stained sections. Patients were followed-up until disease progression.

Results

Viable tumor cells were found on the needle applicators after local ablation in 26.7% of patients. The type of needle applicator used, an open approach, and the omission of track ablation were significantly correlated with viable tumor tissue adherent to the needle applicator. The presence of viable cells was an independent predictor of LTP. The attachment of viable cells to the needle applicators was associated with a shorter time to LTP.

Conclusions

Viable tumor cells adherent to the needle applicators were found after ablation of 26.7% of patients. An independent risk factor for viable cells adherent to the needle applicators is the omission of track ablation. We recommend using only RFA devices that have track ablation functionality. Adherence of viable tumor cells to the needle applicator after local ablation was an independent risk factor for LTP.