Hepatic tumor ablation

Research progress of physical transdermal enhancement techniques in tumor therapy

The advancement and popularity of transdermal drug delivery (TDD) based on the physical transdermal enhancement technique (PTET) has opened a new paradigm for local tumor treatment. The drug can be directly delivered to the tumor site through the skin, thus avoiding the toxic side effects caused by the first-pass effect and achieving high patient compliance. Further development of PTETs has provided many options for antitumor drugs and laid the foundation for future applications of wearable closed-loop targeting drug delivery systems. In this highlight, the different types of PTETs and related mechanisms, and applications of PTET-related tumor detection and therapy are highlighted. According to their type and characteristics, PTETs are categorized as follows: (1) iontophoresis, (2) electroporation, (3) ultrasound, (4) thermal ablation, and (5) microneedles. PTET-related applications in the local treatment of tumors are categorized as follows: (1) melanoma, (2) breast tumor, (3) squamous cell carcinoma, (4) cervical tumor, and (5) others. The challenges and future prospects of existing PTETs are also discussed. This highlight will provide guidance for the design of PTET-based wearable closed-loop targeting drug delivery systems and personalized therapy for tumors.

Role of thermal ablation in the management of colorectal liver metastasis

With a recent randomized prospective trial revealing that thermal ablative therapy as local tumor control improved overall survival (OS) in patients with unresectable colorectal cancer liver metastases (CRLM), thermal ablation continues to remain as an important treatment option in this patient population. Our aim of this article is to review the current role of the ablative therapy in the management of CRLM patients. Main indications for thermal ablation include (I) unresectable liver lesions; (II) in combination with hepatectomy; (III) in patients with significant medical comorbidities or poor performance status (PS); (IV) a small (<3 cm) solitary lesion, which would otherwise necessitate a major liver resection; and (V) patient preference. There are several approaches and modalities for ablative therapy, including open, percutaneous, and laparoscopic approaches, as well as radiofrequency ablation (RFA) and microwave ablation (MWA). Each approach and ablation modality have its own pros and cons. Percutaneous and laparoscopic approaches are preferred due to minimally invasive nature, yet laparoscopic approach has more benefits from thorough intraoperative ultrasound (US) exam as well as complete peritoneal staging with laparoscopy. Similarly, whereas high local tumor failure rate has been a major concern with RFA, MWA or microwave thermosphere ablation (MTA) have demonstrated significantly improved local tumor control due to homogenous tissue heating, ability to reach higher tissue temperatures, and less susceptible to the "heat-sink" effect. Although liver resection is the standard of care for CRLM, there have been some retrospective studies demonstrating similar oncological outcome between ablative therapy and surgical resection in very selected populations with small (<3 cm) solitary CRLM. Lastly, ablative therapy and liver resection should not be mutually exclusive, especially in the management of bilobar liver metastases. Concomitant ablative therapy with hepatectomy may spare the patients from having two-stage hepatectomy with less morbidity. The role of the thermal ablation will continue to evolve in patients with resectable and ablatable lesions owing to newly emerging technology, in addition to new systemic treatment options, including immunotherapy for metastatic colorectal cancer (CRC).

Management of people with early- or very early-stage hepatocellular carcinoma: an attempted network meta-analysis

BACKGROUND

Hepatocellular carcinoma (primary liver cancer) is classified in many ways. The Barcelona Clinic Liver Cancer (BCLC) group staging classifies the cancer based on patient's life expectancy. People with very early- or early-stage hepatocellular carcinoma have single tumour or three tumours of maximum diameter of 3 cm or less, Child-Pugh status A to B, and performance status 0 (fully functional). Management of hepatocellular carcinoma is uncertain.

OBJECTIVES

To assess the comparative benefits and harms of different interventions used in the treatment of early or very early hepatocellular carcinoma through a network meta-analysis and to generate rankings of the available interventions according to their safety and efficacy. However, it was not possible to assess whether the potential effect modifiers were similar across different comparisons. Therefore, we did not perform the network meta-analysis and instead assessed the benefits and harms of different interventions versus each other or versus sham or no intervention using standard Cochrane methodology.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, and trials registers to September 2016 to identify randomised clinical trials (RCTs) on hepatocellular carcinoma.

SELECTION CRITERIA

We included only RCTs, irrespective of language, blinding, or publication status, in participants with very early- or early-stage hepatocellular carcinoma, irrespective of the presence of cirrhosis, portal hypertension, aetiology of hepatocellular carcinoma, size and number of the tumours, and future remnant liver volume. We excluded trials including participants who were previously liver transplanted. We considered interventions compared with each other, sham, or no intervention.

DATA COLLECTION AND ANALYSIS

We calculated the odds ratio, mean difference, rate ratio, or hazard ratio with 95% confidence intervals using both fixed-effect and random-effects models based on available-participant analysis with Review Manager 5. We assessed the risk of bias according to Cochrane, controlled risk of random errors with Trial Sequential Analysis using Stata, and the quality of the evidence using GRADE.

MAIN RESULTS

Eighteen trials met the inclusion criteria for this review. Four trials (593 participants; 574 participants included for one or more analyses) compared surgery versus radiofrequency ablation in people with early hepatocellular carcinoma, eligible to undergo surgery. Fourteen trials (2533 participants; 2494 participants included for various analyses) compared different non-surgical interventions in people with early hepatocellular carcinoma, not eligible to undergo surgery. Overall, the quality of evidence was low or very low for all outcomes for both comparisons. Surgery versus radiofrequency ablationThe majority of participants had cirrhotic livers, and the hepatocellular carcinoma was of viral aetiology. The trials did not report the participants' portal hypertension status or whether they received adjuvant antiviral treatment or adjuvant immunotherapy. The average follow-up ranged from 29 months to 42 months (3 trials).There was no evidence of a difference in all-cause mortality at maximal follow-up for surgery versus radiofrequency ablation (hazard ratio 0.80, 95% confidence interval (CI) 0.60 to 1.08; 574 participants; 4 trials; I² = 68). Cancer-related mortality was lower in the surgery group (20/115 (17.4%)) than in the radiofrequency ablation group (43/115 (37.4%)) (odds ratio 0.35, 95% CI 0.19 to 0.65; 230 participants; 1 trial). Serious adverse events (number of participants) was higher in the surgery group (14/60 (23.3%)) than in the radiofrequency ablation group (1/60 (1.7%)) (odds ratio 17.96, 95% CI 2.28 to 141.60; 120 participants; 1 trial). The number of serious adverse events was higher in the surgery group (adjusted rate 11.3 events per 100 participants) than in the radiofrequency ablation group (3/186 (1.6 events per 100 participants)) (rate ratio 7.02, 95% CI 2.29 to 21.46; 391 participants; 2 trials; I² = 0%). None of the trials reported health-related quality of life. One trial was funded by a party with vested interests; three trials were funded by parties without any vested. Non-surgical interventionsThe majority of participants had cirrhotic livers, and the hepatocellular carcinoma was of viral aetiology. Most trials did not report the portal hypertension status of the participants, and none of the trials reported whether the participants received adjuvant antiviral treatment or adjuvant immunotherapy. The average follow-up ranged from 6 months to 37 months (11 trials). Trial participants, who were not eligible for surgery, were treated with radiofrequency ablation, laser ablation, microwave ablation, percutaneous acetic acid injection, percutaneous alcohol injection, a combination of radiofrequency ablation with systemic chemotherapy, a combination of radiofrequency ablation with percutaneous alcohol injection, a combination of transarterial chemoembolisation with percutaneous alcohol injection, or a combination of transarterial chemoembolisation with radiofrequency ablation.The mortality at maximal follow-up was higher in the percutaneous acetic acid injection (hazard ratio 1.77, 95% CI 1.12 to 2.79; 125 participants; 1 trial) and percutaneous alcohol injection (hazard ratio 1.49, 95% CI 1.18 to 1.88; 882 participants; 5 trials; I² = 57%) groups compared with the radiofrequency ablation group. There was no evidence of a difference in all-cause mortality at maximal follow-up for any of the other comparisons. The proportion of people with cancer-related mortality at maximal follow-up was higher in the percutaneous alcohol injection group (adjusted proportion 16.8%) compared with the radiofrequency ablation group (20/232 (8.6%)) (odds ratio 2.18, 95% CI 1.22 to 3.89; 458 participants; 3 trials; I² = 0%). There was no evidence of a difference in any of the comparisons that reported serious adverse events (number of participants or number of events). None of the trials reported health-related quality of life. Five trials were funded by parties without any vested interest; the source of funding was not available in the remaining trials.

AUTHORS' CONCLUSIONS

The evidence was of low or very low quality. There was no evidence of a difference in all-cause mortality at maximal follow-up between surgery and radiofrequency ablation in people eligible for surgery. All-cause mortality at maximal follow-up was higher with percutaneous acetic acid injection and percutaneous alcohol injection than with radiofrequency ablation in people not eligible for surgery. There was no evidence of a difference in all-cause mortality at maximal follow-up for the other comparisons. High-quality RCTs designed to assess clinically important differences in all-cause mortality and health-related quality of life, and having an adequate follow-up period (approximately five years) are needed.

Laparoscopic image-based navigation for microwave ablation of liver tumors-A multi-center study

BACKGROUND

Stereotactic navigation technology has been proposed to augment accuracy in targeting intrahepatic lesions for local ablation therapy. This retrospective study evaluated accuracy, efficacy, and safety when using laparoscopic image-guided microwave ablation (LIMA) for malignant liver tumors.

METHODS

All patients treated for malignant liver lesions using LIMA at two European centers between 2013 and 2015 were included for analysis. A landmark-based registration technique was applied for intraoperative tumor localization and positioning of ablation probes. Intraoperative efficiency of the procedure was measured as number of registration attempts and time needed to achieve sufficient registration accuracy. Technical accuracy was assessed as Fiducial Registration Error (FRE). Outcome at 90 days including mortality, postoperative morbidity, rates of incomplete ablations, and early intrahepatic recurrences were reported.

RESULTS

In 34 months, 54 interventions were performed comprising a total of 346 lesions (median lesions per patient 3 (1-25)). Eleven patients had concomitant laparoscopic resections of the liver or the colorectal primary tumor. Median time for registration was 4:38 min (0:26-19:34). Average FRE was 8.1 ± 2.8 mm. Follow-up at 90 days showed one death, 24% grade I/II, and 4% grade IIIa complications. Median length of hospital stay was 2 days (1-11). Early local recurrence was 9% per lesion and 32% per patient. Of these, 63% were successfully re-ablated within 6 months.

CONCLUSIONS

LIMA does not interfere with the intraoperative workflow and results in low complication and early local recurrence rates, even when simultaneously targeting multiple lesions. LIMA may represent a valid therapy option for patients with extensive hepatic disease within a multimodal treatment approach.

Management of people with intermediate-stage hepatocellular carcinoma: an attempted network meta-analysis

BACKGROUND

There is significant uncertainty in the treatment of intermediate-stage hepatocellular carcinoma which is defined by the Barcelona Clinic Liver Cancer (BCLC) as hepatocellular carcinoma stage B with large, multi-nodular, Child-Pugh status A to B, performance status 0 to 2, and without vascular occlusion or extrahepatic disease.

OBJECTIVES

To assess the comparative benefits and harms of different interventions used in the treatment of intermediate-stage hepatocellular carcinoma (BCLC stage B) through a network meta-analysis and to generate rankings of the available interventions according to their safety and efficacy. However, we found only one comparison. Therefore, we did not perform the network meta-analysis, and we assessed the comparative benefits and harms of different interventions versus each other, or versus placebo, sham, or no intervention (supportive treatment only) using standard Cochrane methodology.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and randomised clinical trials registers to September 2016 to identify randomised clinical trials on hepatocellular carcinoma.

SELECTION CRITERIA

We included only randomised clinical trials, irrespective of language, blinding, or publication status, in participants with intermediate-stage hepatocellular carcinoma, irrespective of the presence of cirrhosis, size, or number of the tumours (provided they met the criteria of intermediate-stage hepatocellular carcinoma), of presence or absence of portal hypertension, of aetiology of hepatocellular carcinoma, and of the future remnant liver volume. We excluded trials which included participants who had previously undergone liver transplantation. We considered any of the various interventions compared with each other or with no active intervention (supportive treatment only). We excluded trials which compared variations of the same intervention: for example, different methods of performing transarterial chemoembolisation.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We calculated the hazard ratio (HR) with 95% confidence intervals (CI) using both fixed-effect and random-effects models based on available-participant analysis with Review Manager. We assessed risk of bias according to Cochrane, controlled risk of random errors with Trial Sequential Analysis using Stata, and assessed the quality of the evidence using GRADE.

MAIN RESULTS

Three randomised clinical trials, including 430 participants, met the inclusion criteria for this review; however, data from two trials with 412 participants could be included in only one primary outcome (i.e. mortality). All three trials were at high risk of bias. All three trials included supportive care as cointervention. The comparisons included in the two trials reporting on mortality were: systemic chemotherapy with sorafenib versus no active intervention; and transarterial chemoembolisation plus systemic chemotherapy with sorafenib versus transarterial chemoembolisation alone. The trials did not report the duration of follow-up; however, it appeared that the participants were followed up for a period of about 18 to 30 months. The majority of the participants in the trials had cirrhotic livers. The trials included participants with intermediate-stage hepatocellular carcinoma arising from viral and non-viral aetiologies. The trials did not report the portal hypertension status of the participants. The mortality was 50% to 70% over a median follow-up period of 18 to 30 months. There was no evidence of difference in mortality at maximal follow-up between systemic chemotherapy versus no chemotherapy (hazard ratio 0.85, 95% CI 0.60 to 1.18; participants = 412; studies = 2; I² = 0%; very low quality evidence). A subgroup analysis performed by stratifying the analysis by the presence or absence of transarterial chemoembolisation as cointervention did not alter the results. None of the trials reported on serious adverse events other than mortality, health-related quality of life, recurrence of hepatocellular carcinoma, or length of hospital stay. One of the trials providing data was funded by the pharmaceutical industry, the other did not report the source of funding, and the trial with no data for the review was also funded by the pharmaceutical industry. We found two ongoing trials.

AUTHORS' CONCLUSIONS

Currently, there is no evidence from randomised clinical trials that people with intermediate-stage hepatocellular carcinoma would benefit from systemic chemotherapy with sorafenib either alone or when transarterial chemoembolisation was used as a cointervention (very low quality evidence). We need high-quality randomised clinical trials designed to measure differences in clinically important outcomes (e.g. all-cause mortality or health-related quality of life).

Safety and advantages of combined resection and microwave ablation in patients with bilobar hepatic malignancies

BACKGROUND

The multimodality approach has significantly improved outcomes for hepatic malignancies. Microwave ablation is often used in isolation or succession, and seldom in combination with resection. Potential benefits and pitfalls from combined resection and ablation therapy in patients with complex and extensive bilobar hepatic disease have not been well defined.

METHODS

A review of the University of Louisville prospective Hepato-Pancreatico-Biliary Patients database was performed with multi-focal bilobar disease that underwent microwave ablation with resection or microwave only included.

RESULTS

One hundred and eight were treated with microwave only (MWA, n = 108) or combined resection and ablation (CRA, n = 84) and were compared with similar disease-burden patients undergoing resection only (n = 84). The groups were comparable except that the MWA group was older (p = .02) and with higher co-morbidities (diabetes, hepatitis). The resection group had larger tumours (4 vs. 3.2 and 3 cm) but the CRA group had more numerous lesions (4 vs. 3 and 2, p = .002). Short-term outcomes including morbidity (47.6% vs. 43%, p = .0715) were similar between the CRA and resection only groups. Longer operative time (164 vs. 126 min, p = .003) and need for blood transfusion (p = .001) were independent predictors of complications. Survival analyses for colorectal metastasis patients (n = 158) demonstrated better overall survival (OS) (43.9 vs. 37.6 and 30.5 months, p = .035), disease-free survival (DFS) (38 vs. 26.6 and 16.9 months, p = .028) and local recurrence-free survival (LRFS) (55.4 vs. 17 and 22.9 months, p < .001) with resection only.

CONCLUSION

The use of microwave ablation in addition to surgical resection did not significantly increase the morbidities or short-term outcomes. In combination with systemic and other local forms of therapy, combined resection and ablation is a safe and effective procedure.

Single-stage resection and microwave ablation for bilobar colorectal liver metastases

BACKGROUND

Patients undergoing liver resection combined with microwave ablation (MWA) for bilobar colorectal metastasis may have similar overall survival to patients who undergo two-stage hepatectomy, but with less morbidity.

METHODS

This was a multi-institutional evaluation of patients who underwent MWA between 2003 and 2012. Morbidity (90-day) and mortality were compared between patients who had MWA alone and those who underwent combined resection and MWA (CRA). Mortality and overall survival after CRA were compared with published data on two-stage resections.

RESULTS

Some 201 patients with bilobar colorectal liver metastasis treated with MWA from four high-volume institutions were evaluated (100 MWA alone, 101 CRA). Patients who had MWA alone were older, but the groups were otherwise well matched demographically. The tumour burden was higher in the CRA group (mean number of lesions 3·9 versus 2·2; P = 0·003). Overall (31·7 versus 15·0 per cent; P = 0·006) and high-grade (13·9 versus 5·0 per cent; P = 0·030) complication rates were higher in the CRA group. Median overall survival was slightly shorter in the CRA group (38·4 versus 42·2 months; P = 0·132) but disease-free survival was similar (10·1 versus 9·3 months; P = 0·525). The morbidity and mortality of CRA compared favourably with rates in the existing literature on two-stage resection, and survival data were similar.

CONCLUSION

Single-stage hepatectomy and MWA resulted in survival similar to that following two-stage hepatectomy, with less overall morbidity.

Long-term survival following radiofrequency ablation of colorectal liver metastases: A retrospective study

AIM: To retrospectively evaluate the long-term survival of patients that received radiofrequency ablation (RFA) therapies of colorectal liver metastases.

METHODS: In 2005 to 2008, RFA of 105 colorectal liver metastases (CRLM) were performed on 49 patients in our institution. The liver metastases were evaluated, both before and after ablation therapies, with contrast enhanced computerised tomography and contrast enhanced ultrasonography. Histological evidence of malignant liver metastases was obtained in the few instances where contrast enhanced ultrasonography gave equivocal results. Accesses to the CRLM were guided ultrasonically in all patients. The data obtained from records of these ablations were retrospectively analysed and survival data were compared with existing studies in the literature.

RESULTS: 1-, 2-, 3-, 4- and 5-year survival rates, when no stringent selection criteria were applied, were 92%, 65%, 51%, 41% and 29% respectively. To explore the impact of the number and size of CRLM on patients’ survival, an exclusion of 13 patients (26.5%) with number of CRLM ≥ 5 and tumour size ≥ 40 mm resulted in 1-, 2-, 3-, 4- and 5-year survival rates improving to 94%, 69%, 53%, 42% and 31% respectively. It is of note that 9 of 49 patients developed extra-hepatic metastases, not visible or seen on pre-treatment scans, just after RFA treatment. These patients had poorer survival. The development of extra-hepatic metastases in nearly 20% of the patients included in our study can partly account for modestly lower survival rates as compared with earlier studies in the literature.

CONCLUSION: Our study underscores the fact that optimum patients’ selection before embarking on RFA treatment is vitally important to achieving a superior outcome.

Optimal Ablation Volumes Are Achieved at Submaximal Power Settings in a 2.45-GHz Microwave Ablation System

Introduction. Local ablative therapies, including microwave ablation (MWA), are common treatment modalities for in situ tumor destruction. Currently, 2.45-GHz ablation systems are gaining prominence because of the shorter application times required. The aims of this study were to determine optimal power and time to ablation volume (AbV) ratios for a new 1.8-mm–2.45-GHz antenna using ex vivo tissue models. Methods. The 1.8-mm–2.45-GHz Accu2i MWA system was employed to perform ablations in bovine liver, porcine muscle, and porcine kidney ex vivo. Whole tissues were prewarmed (35°C) and multiple ablations performed at power settings of 60 to 180 W for 2- to 6-minute time intervals. Postablation, tissues were dissected, AbVs calculated, and correlations to power and time settings made. Results. Significant increases in AbV were measured between each of the time points for a constant power setting in all 3 tissues. Increasing power settings led to significant increases in AbV at power settings ≤140 W. However, no significant increase in AbV was obtained at power settings >140 W. Conclusions. Optimal efficiency for MWA using a new 1.8-mm–2.45-GHz system is achieved at settings of ≤140 W for 6 minutes in a range of ex vivo tissue and no additional benefit occurs by increasing the power setting to 180 W in these tissues.

Laparoscopic microwave ablation of human liver tumours using a novel three-dimensional magnetic guidance system

BACKGROUND

Accurate antenna placement is essential for effective microwave ablation (MWA) of lesions. Laparoscopic targeting is made particularly challenging in liver tumours by the needle's trajectory as it passes through the abdominal wall into the liver. Previous optical three-dimensional guidance systems employing infrared technology have been limited by interference with the line of sight during procedures.

OBJECTIVE

The aim of this study was to evaluate a newly developed magnetic guidance system for laparoscopic MWA of liver tumours in a pilot study.

METHODS

Thirteen patients undergoing laparoscopic MWA of liver tumours gave consent to their participation in the study and were enrolled. Lesion targeting was performed using the InnerOptic AIM™ 3-D guidance system to track the real-time position and orientation of the antenna and ultrasound probe.

RESULTS

A total of 45 ablations were performed on 34 lesions. The median number of lesions per patient was two. The mean ± standard deviation lesion diameter was 18.0 ± 9.2 mm and the mean time to target acquisition was 3.5 min. The first-attempt success rate was 93%. There were no intraoperative or immediate postoperative complications. Over an average follow-up of 7.8 months, one patient was noted to have had an incomplete ablation, seven suffered regional recurrences, and five patients remained disease-free.

CONCLUSIONS

The AIM™ guidance system is an effective adjunct for laparoscopic ablation. It facilitates a high degree of accuracy and a good first-attempt success rate, and avoids the line of site interference associated with infrared systems.

Ablation therapy for hepatocellular carcinoma: past, present and future perspectives

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide, and is most commonly found in the setting of liver cirrhosis. Treatment of HCC must consider both the tumors present, as well as the remaining dysfunctional liver that both hinders treatment and can produce additional HCC over time. Ablation is an evolving part of the multimodality treatment approach to HCC that can effectively destroy tumors while preserving surrounding liver parenchyma. New technologies have made ablation an indispensable tool in the treatment of all stages of HCC. This review presents the history, present technologies and future potential of ablation in the treatment of HCC.

Microwave ablation using 915-MHz and 2.45-GHz systems: what are the differences?

OBJECTIVES

This study was conducted to evaluate differences between 915-MHz and 2.45-GHz microwave ablation (MWA) systems in the ablation of hepatic tumours.

METHODS

A retrospective analysis of patients undergoing hepatic tumour MWA utilizing two different systems over a 10-month period was carried out.

RESULTS

Data for a total of 48 patients with a mean age of 58 ± 1.24 years were analysed. A total of 124 tumours were ablated; 72 tumours were ablated with a 915-MHz system and 52 with a 2.45-GHz system. Mean tumour diameters were 1.7 ± 0.1 cm in the 915-MHz group and 2.5 ± 0.2 cm in the 2.45-GHz group (P < 0.01). Mean ablation time per burn was 8.1 ± 0.3 min in the 915-MHz group and 4.0 ± 0.1 min in the 2.45-GHz group (P < 0.01). The mean number of burns per lesion was 2.0 ± 0.1 in the 915-MHz group and 1.7 ± 0.1 in the 2.45-GHz group (P < 0.05). The mean ablation time per lesion was 9.7 ± 0.7 min in the 915-MHz group, and 6.6 ± 0.6 min in the 2.45-GHz group (P < 0.01). The 2.45-GHz system demonstrated a better correlation between ablation time and tumour size (r(2) = 0.6222) than the 915-MHz system; (r(2) = 0.0696). Mean total energy applied per lesion, and energy applied per cm, were greater with the 915-MHz system (P < 0.05 and P < 0.01, respectively). Total energy applied per lesion was similarly correlated for the 2.45-GHz (r(2) = 0.6263) and 915-MHz (r(2) = 0.7012) systems. Mean total energy applied per cm/min was greater with the 2.45-GHz system (P < 0.05).

CONCLUSIONS

Both 915-MHz and 2.45-GHz MWA systems achieve reproducible hepatic tumour ablation. The 2.45-GHz system achieves equivalent, but more predictable and faster ablations using a single antenna system.

Safety and early efficacy of irreversible electroporation for hepatic tumors in proximity to vital structures

INTRODUCTION

Irreversible electroporation (IRE) has shown promise for ablation of lesions in proximity to vital structures in the preclinical setting. This study aims to evaluate the safety and efficacy of IRE for hepatic tumors in the clinical setting.

METHODS

An IRB approved prospective registry of patients undergoing IRE for hepatic tumors over a 2-year period. Factors analyzed included patient and tumor characteristics, treatment related complications, and local recurrence free survival (LRFS) for ablated lesions. LRFS was calculated according to Kaplan-Meier, with secondary analyses stratified by procedural approach (laparotomy, laparoscopy, and percutaneous) and tumor histology.

RESULTS

There were 44 patients undergoing 48 total IRE procedures, 20 colorectal mets, 14 hepatocellular, and 10 other metastatsis. Initial success was achieved in 46 (100%) treatments. Five patients had 9 adverse events, with all complications resolving within 30 days. LRFS at 3, 6, and 12 months was 97.4%, 94.6%, and 59.5%. There was a trend toward higher recurrence rates for tumors over 4 cm (HR 3.236, 95% CI: 0.585-17.891; P = 0.178).

CONCLUSIONS

IRE appears to be a safe treatment for hepatic tumors in proximity to vital structures. Further prospective evaluation is needed to determine the optimal effectiveness of IRE in relation to size and technique for IRE of the liver.

Hepatic tumor ablation: application in a community hospital setting

Primary liver tumors are a common clinical problem in the United States and worldwide. Resection has historically been used to treat liver lesions. Commonly used liver-directed therapies include transarterial chemoembolization, selective internal radiation therapy, and ablative therapy. Only ablative therapy can cause direct destruction of the targeted tissue. The commercially available modalities in the United States are all based on thermoablative technology. This article examines the various ablative technologies and their application, as well as how these procedures can be performed safely and with optimal outcomes, in a community cancer center.

International multicentre prospective study on microwave ablation of liver tumours: preliminary results

BACKGROUND

Microwave ablation (MWA) is increasingly utilized in the treatment of hepatic tumours. Promising single-centre reports have demonstrated its safety and efficacy, but this modality has not been studied in a prospective, multicentre study.

METHODS

Eighteen international centres recorded operative and perioperative data for patients undergoing MWA for tumours of any origin in a voluntary Internet-based database. All patients underwent operative MWA using a 2.45-GHz generator with a 5-mm antenna.

RESULTS

Of the 140 patients, 114 (81.4%) were treated with MWA alone and 26 (18.6%) were treated with MWA combined with resection. Multiple tumours were treated with MWA in 40.0% of patients. A total of 299 tumours were treated in these 140 patients. The median size of ablated lesions was 2.5 cm (range: 0.5-9.5 cm). Tumours were treated with a median of one application (range: 1-6 applications) for a median of 4 min (range: 0.5-30.0 min). A power setting of 100 W was used in 78.9% of cases. Major morbidity was 8.3% and in-hospital mortality was 1.9%.

CONCLUSIONS

These multi-institution data demonstrate rapid ablation time and low morbidity and mortality rates in patients undergoing operative MWA with a high rate of multiple ablations and concomitant hepatic resection. Longterm follow-up will be required to determine the efficacy of MWA relative to other forms of ablative therapy.

Colour doppler ultrasonography provides real-time microwave field visualisation in an ex vivo porcine model

INTRODUCTION

Microwave ablation (MWA) uses non-ionising thermal energy to cause cell death by coagulative necrosis. Colour Doppler ultrasound (US) produces a spherical image during tissue ablation that appears to approximate the microwave near field (MNF) in shape and size. The aim of the present study was to determine whether colour Doppler US images observed during microwave ablation correlate with the actual thermocoagulation zone (TCZ) observed in liver tissue.

METHODS

Twenty MWAs were performed in ex vivo bovine liver using a 915-MHz ablation antenna set to 45 W for 6 min concomitant with Doppler US imaging. The edges of spherical images observed with colour Doppler US were marked circumferentially in the tissue. The tissue was transected parallel to the angle of antenna insertion, and the distances between methylene blue markings and the TCZ were measured.

RESULTS

The images observed using colour Doppler US were similar in size and shape to the actual TCZ observed in the tissue. The mean distance between the observed colour Doppler US field diameter and the measured TCZ was 2 ± 1 mm.

CONCLUSIONS

Using colour Doppler US, the visualised field during MWA correlates with the TCZ in an ex vivo bovine liver model. Real-time, dynamic feedback of the treatment area may increase the effectiveness of MWA for liver tumours in vivo.

Real-time three-dimensional guided ultrasound targeting system for microwave ablation of liver tumours: a human pilot study

OBJECTIVES

This study aimed to evaluate a novel three-dimensional ultrasound (US) guidance system for use in hepatic microwave ablation (MWA).

METHODS

An in vitro assessment was performed in which users with different degrees of experience were evaluated for accuracy in targeting phantom lesions embedded in agar using US alone, or US in conjunction with the InVision™ System (IVS). An eight-patient pilot trial of the IVS was then performed in the setting of open hepatic MWA, in which lesions would otherwise have been targeted with conventional US.

RESULTS

In vitro studies demonstrated that the IVS significantly improved targeting accuracy at all levels of operator experience (novice, beginner and expert). In the human trial, a total of 31 tumours were targeted and all lesions were hit in one pass, as assessed by independent US image observations. There were no adverse operative events; however, there was minor line-of-sight interference with the infra-red tracking mechanism when some lesions high on the dome of the liver were targeted.

CONCLUSIONS

The IVS significantly increased the accuracy of complex targeting procedures of phantom lesions and enhanced targeting in an eight-patient clinical pilot study. During the accrual phase of this pilot study, the development of improved non-optical tracking hardware obviated the requirement to maintain a direct line of sight. The trial was then halted prematurely in order to focus on the application of the IVS utilizing this non-optical modality.