Clinical effectiveness of bipolar radiofrequency ablation for small liver cancers

Thermal immuno-nanomedicine in cancer

Immunotherapy has revolutionized the treatment of patients with cancer. However, promoting antitumour immunity in patients with tumours that are resistant to these therapies remains a challenge. Thermal therapies provide a promising immune-adjuvant strategy for use with immunotherapy, mostly owing to the capacity to reprogramme the tumour microenvironment through induction of immunogenic cell death, which also promotes the recruitment of endogenous immune cells. Thus, thermal immunotherapeutic strategies for various cancers are an area of considerable research interest. In this Review, we describe the role of the various thermal therapies and provide an update on attempts to combine these with immunotherapies in clinical trials. We also provide an overview of the preclinical development of various thermal immuno-nanomedicines, which are capable of combining thermal therapies with various immunotherapy strategies in a single therapeutic platform. Finally, we discuss the challenges associated with the clinical translation of thermal immuno-nanomedicines and emphasize the importance of multidisciplinary and inter-professional collaboration to facilitate the optimal translation of this technology from bench to bedside.

Bipolar radiofrequency ablation treatment of liver cancer employing monopolar needles: A comprehensive investigation on the efficacy of time-based switching

Radiofrequency ablation (RFA) is a thermal ablative treatment method that is commonly used to treat liver cancer. However, the thermal coagulation zone generated using the conventional RFA system can only successfully treat tumours up to 3 cm in diameter. Switching bipolar RFA has been proposed as a way to increase the thermal coagulation zone. Presently, the understanding of the underlying thermal processes that takes place during switching bipolar RFA remains limited. Hence, the objective of this study is to provide a comprehensive understanding on the thermal ablative effects of time-based switching bipolar RFA on liver tissue. Five switch intervals, namely 50, 100, 150, 200 and 300 s were investigated using a two-compartment 3D finite element model. The study was performed using two pairs of RF electrodes in a four-probe configuration, where the electrodes were alternated based on their respective switch interval. The physics employed in the present study were verified against experimental data from the literature. Results obtained show that using a shorter switch interval can improve the homogeneity of temperature distribution within the tissue and increase the rate of temperature rise by delaying the occurrence of roll-off. The coagulation volume obtained was the largest using switch interval of 50 s, followed by 100, 150, 200 and 300 s. The present study demonstrated that the transient thermal response of switching bipolar RFA can be improved by using shorter switch intervals.

Thermal and thermal damage responses during switching bipolar radiofrequency ablation employing bipolar needles: A computational study on the effects of different electrode configuration, input voltage and ablation duration

Recent studies have demonstrated the effectiveness of switching bipolar radiofrequency ablation (bRFA) in treating liver cancer. Nevertheless, the clinical use of the treatment remains less common than conventional monopolar RFA - likely due to the lack of understanding of how the tissues respond thermally to the switching effect. The problem is exacerbated by the numerous possible switching combinations when bRFA is performed using bipolar needles, thus making theoretical deduction and experimental studies difficult. This article addresses this issue via computational modelling by examining if significant variation in the treatment outcome exists amongst six different electrode configurations defined by the X-, C-, U-, N-, Z- and O-models. Results indicated that the tissue thermal and thermal damage responses varied depending on the electrode configuration and the operating conditions (input voltage and ablation duration). For a spherical tumour, 30 mm in diameter, complete ablation could not be attained in all configurations with 70 V input voltage and 5 minutes ablation duration. Increasing the input voltage to 90 V enlarged the coagulation zone in the X-model only. With the other configurations, extending the ablation duration to 10 minutes was found to be the better at enlarging the coagulation zone.

The Efficacy and Therapeutic Outcome of Bipolar Radiofrequency Ablation for the Treatment for Hepatocellular Carcinoma in the Real-World Setting, Compared with Monopolar Radiofrequency Ablation Conducted during the Same Period

BACKGROUND

Several reports have suggested that the bipolar radiofrequency ablation (RFA) system is useful for the treatment of hepatocellular carcinoma (HCC). We evaluated the efficacy and safety of the bipolar RFA system for HCC treatment in the real-world setting.

METHODS

A total of 155 patients with 224 HCC tumors were enrolled. First, we examined the characteristics and outcomes of two RFA systems, monopolar and bipolar. Second, we identified the factors associated with local tumor progression in 72 patients with 104 HCC tumors, who could be followed up for at least 3 months after treatment and had been treated with the bipolar RFA system.

RESULTS

Of the baseline characteristics, tumor size and location were associated with the selection of the bipolar RFA system. A sufficient ablative zone margin (≥5 mm) was obtained by bipolar RFA in 81 of 94 (86.1%). The 1- and 2-year local tumor progression rates were 15.6 and 26.3%, respectively. An alpha-fetoprotein-L3 (AFP-L3) ratio >10% (HR: 7.64; 95% CI: 1.7-39.8, p = 0.007) and an insufficient ablative zone margin (<5 mm) (HR: 4.53; 95% CI: 1.02-20.3, p = 0.047) were related to local tumor progression in Cox regression analysis. Although severe adverse events were not observed in most cases, severe hepatic infarction occurred in 1 patient.

CONCLUSIONS

The bipolar RFA system is safe and effective for HCC treatment. Tumor localization within the liver is an important factor associated with bipolar RFA. Careful follow-up or reconsideration of treatment is necessary for cases with AFP-L3 ratio >10% or insufficient ablative zone margin (<5 mm), which were associated with local tumor progression.

Complications after Radiofrequency Ablation for Hepatocellular Carcinoma: A Multicenter Study Involving 9,411 Japanese Patients

INTRODUCTION

Radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) is considered a safe and minimally invasive procedure. We previously reported that the mortality and complication rates for RFA were 0.038% (5/13,283 patients) and 3.54% (579 complications/16,346 procedures), respectively, from 1999 to 2010 (previous period). In this study, we investigated the clinical criteria for RFA and the mortality and complication rates from 2011 to 2015 (recent period).

METHODS

Data were collected from 25 centers by using a questionnaire developed by the Chugoku-Shikoku Society for Local Ablation Therapy of HCC. The criteria for RFA, RFA modification, use of image-guidance modalities, mortality, and complications during the previous and recent periods were compared.

RESULTS

We evaluated 11,298 procedures for 9,411 patients, including those that involved new devices (bipolar RFA and internally adjustable electrode system). The criterion of hepatic function for RFA increased from a Child-Pugh score ≤8 during the previous period to ≤9 during the recent period. The criteria regarding the tumor location and other risk factors have been expanded recently because of the increased use of several modifications of the RFA procedure and image-guidance modalities. The mortality rate was 0.064% (6/9,411 patients), and the complication rate was 2.92% (330 complications/11,298 procedures). There was no difference in mortality rates between the 2 periods (p = 0.38), but the complication rates was significantly lower during the recent period (p = 0.038).

DISCUSSION AND CONCLUSIONS

Our findings confirmed that RFA, including the use of new devices, is a low-risk procedure for HCC, despite the expansion of the criteria for RFA during the recent period.

A computational model to investigate the influence of electrode lengths on the single probe bipolar radiofrequency ablation of the liver

BACKGROUND AND OBJECTIVES

Recently, there have been calls for RFA to be implemented in the bipolar mode for cancer treatment due to the benefits it offers over the monopolar mode. These include the ability to prevent skin burns at the grounding pad and to avoid tumour track seeding. The usage of bipolar RFA in clinical practice remains uncommon however, as not many research studies have been carried out on bipolar RFA. As such, there is still uncertainty in understanding the effects of the different RF probe configurations on the treatment outcome of RFA. This paper demonstrates that the electrode lengths have a strong influence on the mechanics of bipolar RFA. The information obtained here may lead to further optimization of the system for subsequent uses in the hospitals.

METHODS

A 2D model in the axisymmetric coordinates was developed to simulate the electro-thermophysiological responses of the tissue during a single probe bipolar RFA. Two different probe configurations were considered, namely the configuration where the active electrode is longer than the ground and the configuration where the ground electrode is longer than the active. The mathematical model was first verified with an existing experimental study found in the literature.

RESULTS

Results from the simulations showed that heating is confined only to the region around the shorter electrode, regardless of whether the shorter electrode is the active or the ground. Consequently, thermal coagulation also occurs in the region surrounding the shorter electrode. This opened up the possibility for a better customized treatment through the development of RF probes with adjustable electrode lengths.

CONCLUSIONS

The electrode length was found to play a significant role on the outcome of single probe bipolar RFA. In particular, the length of the shorter electrode becomes the limiting factor that influences the mechanics of single probe bipolar RFA. Results from this study can be used to further develop and optimize bipolar RFA as an effective and reliable cancer treatment technique.

Prospective cohort trial to confirm the efficacy of no-touch radio frequency ablation

BACKGROUND AND AIM

The aim of the present prospective study was to evaluate tumor recurrence (intrasubsegmental recurrence-free survival and local tumor recurrence-free survival) and hepatic functional reserve following no-touch ablation.

METHODS

The prospective cohort study protocols were approved by the institutional ethics committee. All patients provided written, informed consent. Between January 2014 and September 2016, 231 patients with 277 hepatocellular carcinoma nodules were prospectively enrolled. An internally cooled bipolar electrode was used for no-touch ablation, while a monopolar electrode was used for direct puncture ablation. The intrasubsegmental recurrence-free survival rate was the primary end-point. The secondary outcomes were the local recurrence-free survival rate, the disease-free survival rate, and the changes in the Child-Pugh score.

RESULTS

No-touch ablation resulted in significantly higher cumulative intrasubsegmental tumor recurrence-free survival rates than direct puncture ablation (98.0% vs 87.1% at 1 year, 96.9% vs 76.8% at 2 years, and 91.0% vs 68.3% at 3 years, P < 0.001). The no-touch group also showed significantly better local recurrence-free survival and disease-free survival. Even when only primary cases were analyzed, the same results were obtained. To adjust for differences in the background characteristics, inverse probability of treatment weighting adjustment was performed. Only intrasubsegmental tumor recurrence-free survival was significantly better in the no-touch group (hazard ratio [HR], 0.08; 95% confidence interval [CI], 0.02-0.20, P < 0.001); there was no difference in local tumor recurrence-free survival (HR, 0.36; 95% CI, 0.10-1.02, P = 0.071).

CONCLUSIONS

No-touch ablation appears to be an ideal method for the prevention of intrahepatic dissemination.

Transcatheter Arterial Chemoembolization With or Without Radiofrequency Ablation: Outcomes in Patients With Barcelona Clinic Liver Cancer Stage B Hepatocellular Carcinoma

OBJECTIVE

The objective of our study was to clarify the indications for transcatheter arterial chemoembolization (TACE) of the hepatic artery combined with radiofrequency ablation (RFA), which we refer to as "TACE-RFA," for patients with hepatocellular carcinoma (HCC) beyond the Milan criteria. This study assessed the prognoses of patients with intermediate-stage HCC, which we defined as Barcelona Clinic Liver Cancer (BCLC) stage B (hereafter referred to as BCLC-B), according to the BCLC-B substages through treatment in a multicenter study.

MATERIALS AND METHODS

Two-hundred thirty patients with intermediate-stage HCC who were treated from January 2000 to December 2015 were enrolled. These patients were divided into four classes (B1-B4) according to the Bolondi classification. Between these substages, the prognosis of patients who underwent TACE-RFA was compared with that of patients who underwent TACE, the latter of which is the suggested standard therapy for patients with BCLC-B HCC.

RESULTS

TACE-RFA and hepatic resection survival curves were better than those of TACE (p < 0.001 for TACE-RFA vs TACE). In particular, for substages B1 and B2, the overall survival rates of patients who underwent TACE-RFA were significantly higher than those who underwent TACE (B1, p < 0.001 for TACE-RFA vs TACE; B2, p = 0.015 for TACE-RFA vs TACE).

CONCLUSION

The indications for TACE-RFA may be expanding to BCLC-B HCC. For patients with disease classified as substages B1 and B2, TACE-RFA may be a better treatment modality than TACE alone.

Clinical utility of multipolar ablation with a 3-D simulator system for patients with liver cancer

BACKGROUND AND AIM

The aim of this study is to confirm the efficacy of multipolar ablation with a new simulator system, three-dimensional (3-D) sim-Navigator, for patients with hepatocellular carcinoma by assessing relapse-free survival and shape of the ablation volume under clinical conditions.

METHODS

All participants provided written, informed consent, and study protocols were approved by the institutional ethics committee. Twenty-seven patients with 27 nodules were treated by no-touch ablation using the new simulator system. Another 21 patients with 21 nodules treated without the simulator system were enrolled as controls. Tumor progression and shape of ablation volume were assessed. Predictors of tumor progression were assessed by Cox proportional hazard model.

RESULTS

No significant differences in clinical characteristics were seen between groups. Mean sphericity was 0.48 ± 0.07 with 3-D sim-Navigator and 0.37 ± 0.07 without 3-D sim-Navigator (P < 0.001). Median surface-to-volume ratio and compactness were also significantly closer to those of a sphere with 3-D sim-Navigator (P = 0.017, P < 0.001). Relapse-free survival rates at 1 and 1.5 years were 94.1% and 82.4%, respectively, with 3-D sim-Navigator, compared with 83.2% and 55.5% without (P = 0.056). The only independent factor predicting relapse-free survival was use of 3-D sim-Navigator (hazard ratio, 0.12; 95%CI, 0.01-0.87; P = 0.035).

CONCLUSIONS

Ideal ablation area was acquired by this simulation and navigation system in clinics. This system improved local tumor progression by facilitating appropriate insertion of multiple electrodes.

Multipolar versus monopolar radiofrequency ablation for hepatocellular carcinoma in the caudate lobe: Results of a propensity score analysis

AIM

This study aimed to compare multipolar radiofrequency ablation (RFA) with monopolar RFA as the major treatment for nodules of hepatocellular carcinoma in the caudate lobe.

METHODS

This retrospective study was approved by the institutional review board. Data were reviewed from 101 patients who met the Milan criteria and were treated by multipolar RFA (n = 22) or monopolar RFA (n = 79). After propensity score matching, complications and local tumor progression were compared between the two groups.

RESULTS

Before propensity score matching (n = 101), the 2-year relapse-free survival rates for multipolar and monopolar RFA (65.1% vs. 38.8%, respectively; P = 0.064) and the local tumor progression rate (12.5% vs. 14.9%, respectively; P = 0.313) were not significantly different. There were no significant differences between the two RFA techniques by treatment efficacy of transcatheter hepatic arterial embolization, location of tumor, and puncture route. After matching (n = 44), the 2-year relapse-free survival rate for the multipolar and monopolar groups (65.1% vs. 22.7%, respectively; P = 0.004) was significantly different, and the local tumor progression rate (12.5% vs. 22.9%, respectively; P = 0.004) was significantly different. No severe complications occurred in the patients treated by multipolar RFA.

CONCLUSION

Multipolar RFA appears to be a safe and effective method for hepatocellular carcinoma nodules in the caudate lobe.

No-touch radiofrequency ablation using multiple electrodes: An in vivo comparison study of switching monopolar versus switching bipolar modes in porcine livers

Objective

To evaluate the in vivo technical feasibility, efficiency, and safety of switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) as a no-touch ablation technique in the porcine liver.

Materials and methods

The animal care and use committee approved this animal study and 16 pigs were used in two independent experiments. In the first experiment, RFA was performed on 2-cm tumor mimickers in the liver using a no-touch technique in the SM mode (2 groups, SM1: 10 minutes, n = 10; SM2: 15 minutes, n = 10) and SB-mode (1 group, SB: 10 minutes, n = 10). The technical success with sufficient safety margins, creation of confluent necrosis, ablation size, and distance between the electrode and ablation zone margin (DEM), were compared between groups. In the second experiment, thermal injury to the adjacent anatomic organs was compared between SM-RFA (15 minutes, n = 13) and SB-RFA modes (10 minutes, n = 13).

Results

The rates of the technical success and the creation of confluent necrosis were higher in the SB group than in the SM1 groups (100% vs. 60% and 90% vs. 40%, both p < 0.05). The ablation volume in the SM2 group was significantly larger than that in the SB group (59.2±18.7 cm³ vs. 39.8±9.7 cm^3,p < 0.05), and the DEM in the SM2 group was also larger than that in the SB group (1.39±0.21 cm vs. 1.07±0.10 cm, p < 0.05). In the second experiment, the incidence of thermal injury to the adjacent organs and tissues in the SB group (23.1%, 3/13) was significantly lower than that in the SM group (69.2%, 8/13) (p = 0.021).

Conclusion

SB-RFA was more advantageous for a no-touch technique for liver tumors, showing the potential of a better safety profile than SM-RFA.

No-Touch Radiofrequency Ablation: A Comparison of Switching Bipolar and Switching Monopolar Ablation in Ex Vivo Bovine Liver

OBJECTIVE

To evaluate the feasibility, efficiency, and safety of no-touch switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) using ex vivo bovine livers.

MATERIALS AND METHODS

A pork loin cube was inserted as a tumor mimicker in the bovine liver block; RFA was performed using the no-touch technique in the SM (group A1; 10 minutes, n = 10, group A2; 15 minutes, n = 10) and SB (group B; 10 minutes, n = 10) modes. The groups were compared based on the creation of confluent necrosis with sufficient safety margins, the dimensions, and distance between the electrode and ablation zone margin (DEM). To evaluate safety, small bowel loops were placed above the liver surface and 30 additional ablations were performed in the same groups.

RESULTS

Confluent necroses with sufficient safety margins were created in all specimens. SM RFA created significantly larger volumes of ablation compared to SB RFA (all p < 0.001). The DEM of group B was significantly lower than those of groups A1 and A2 (all p < 0.001). Although thermal injury to the small bowel was noted in 90%, 100%, and 30% of the cases in groups A1, A2, and B, respectively, full depth injury was noted only in 60% of group A2 cases.

CONCLUSION

The no-touch RFA technique is feasible in both the SB and SM modes; however, SB RFA appears to be more advantageous compared to SM RFA in the creation of an ablation zone while avoiding the unnecessary creation of an adjacent parenchymal ablation zone or adjacent small bowel injuries.

Short-Term Results of Laparoscopic Radiofrequency Ablation Using a Multipolar System for Localized Hepatocellular Carcinoma

BACKGROUND AND AIM

Multipolar radiofrequency ablation (RFA) is feasible for the treatment of hepatocellular carcinoma (HCC) for which a large ablative area is planned, and it imposes a light physical burden on patients. Multipolar RFA via the percutaneous approach is performed in the majority of cases, but the efficacy of multipolar RFA with a laparoscopic approach has rarely been studied. This study aimed to evaluate the efficacy and safety of multipolar laparoscopic RFA (LRA) for localized HCC over the short term.

METHODS

From January 2014 to January 2016, 77 consecutive patients with 130 HCCs treated by multipolar LRA were assessed. One to three bipolar needle applicators were inserted under laparoscopic ultrasonography guidance, regardless of tumor location. We intended to achieve parallel insertions and no-touch ablation as much as possible.

RESULTS

The median size of the main tumor was 22 mm (range, 10-42 mm). The median follow-up time was 13.6 months (range, 3.1-24.8 months). In all cases, a sufficient ablative area was obtained as planned, without thermal injury of adjacent organs. During the follow-up period, all patients were alive with no local tumor progression, while intrahepatic recurrence distant from the primary site occurred in 7 patients. The 2-year local tumor progression-free survival rate and overall cancer-free survival rate were 100 and 81.6%, respectively. There were no procedural major complications caused prolonging the hospitalization, and all patients were discharged without subjective symptoms 4-7 days after LRA.

CONCLUSIONS

Multipolar LRA was efficacious in the treatment of localized HCCs by safely achieving a good ablative area.

Quick and stable parallel puncture of hepatic tumors using a double-barreled needle direction system for ultrasound-guided bipolar radiofrequency ablation

AIM

In bipolar radiofrequency ablation (RFA) therapy, insertion of multiple needles at appropriate points on a target is difficult. The aim of our study was to evaluate a simplified method for multi-electrode insertion using a newly developed double-barreled needle guidance system for percutaneous RFA of hepatic tumors.

METHODS

RFA using two bipolar electrodes was performed in 15 consecutive patients (nine men, six women; mean age, 72.0 ± 8.2 years) with a solitary small (≤3 cm) hepatic tumor. The first five nodules were treated using the conventional puncture method with the standard attachment, then 10 nodules were ablated using the parallel puncture method with the double-barreled attachment. The times required for double-needle placement and the shapes of the ablated areas were compared between the two puncture methods.

RESULTS

The parallel puncture method required a shorter time for double-needle placement than the conventional method (12 s [range, 8-24] vs 96 s [range, 50-240]; P = 0.0003), and allowed continuous observation of the tip of all needles and the size of the ablated area as it increased until completion of the ablation. The method also provided a stable ellipsoidal ablated area. The median height, width and thickness were 30 mm (range, 22-34), 30 mm (range, 21-33) and 20 mm (range, 7-25), respectively, using 20-mm electrodes, and 34 mm (range, 32-41), 36 mm (range, 35-38) and 24 mm (range, 23-24), respectively, using 30-mm electrodes.

CONCLUSION

The parallel puncture method may be a feasible procedure for multi-needle RFA therapy.

Usefulness of a New Three-Dimensional Simulator System for Radiofrequency Ablation

Multipuncture radiofrequency ablation is expected to produce a large ablated area and reduce intrahepatic recurrence of hepatocellular carcinoma; however, it requires considerable skill. This study evaluated the utility of a new simulator system for multipuncture radiofrequency ablation. To understand positioning of multipuncture electrodes on three-dimensional images, we developed a new technology by expanding real-time virtual ultrasonography. We performed 21 experimental punctures in phantoms. Electrode insertion directions and positions were confirmed on computed tomography, and accuracy and utility of the simulator system were evaluated by measuring angles and intersections for each electrode. Moreover, to appropriately assess placement of the three electrodes, puncture procedures with or without the simulator were performed by experts and non-experts. Technical success was defined as maximum angle and distance ratio, as calculated by maximum and minimum distances between electrodes. In punctures using 2 electrodes, correlations between angles on each imaging modality were strong (ultrasound vs. simulator: r = 0.991, p<0.001, simulator vs. computed tomography: r = 0.991, p<0.001, ultrasound vs. computed tomography: r = 0.999, p<0.001). Correlations between distances in each imaging modality were also strong (ultrasound vs. simulator: r = 0.993, p<0.001; simulator vs. computed tomography: r = 0.994, p<0.001; ultrasound vs. computed tomography: r = 0.994, p<0.001). In cases with 3 electrodes, distances between each electrode correlated strongly (yellow-labeled vs. red-labeled: r = 0.980, p<0.001; red-labeled vs. blue-labeled: r = 0.953, p<0.001; yellow-labeled vs. blue-labeled: r = 0.953, p<0.001). Both angle and distance ratio (expert with simulator vs. without simulator; p = 0.03, p = 0.02) were significantly smaller in procedures performed by experts using the simulator system. The new simulator system appears to accurately guide electrode positioning. This simulator system could allow multipuncture radiofrequency ablation to be performed more effectively and comfortably.

Treatment efficacy and safety of ultrasound-guided percutaneous bipolar radiofrequency ablation for benign thyroid nodules

OBJECTIVE

To evaluate the therapeutic efficacy and safety of ultrasound-guided percutaneous bipolar radiofrequency ablation (BRFA) of benign thyroid nodules by comparison with a matched untreated control group.

METHODS

The therapeutic efficacy and safety in 35 patients who were subjected to a single session of ultrasound-guided percutaneous BRFA (Group A) for benign thyroid nodules were compared with those in 35 untreated patients (Group B) with benign nodules. The benign nature of all the nodules was confirmed by ultrasound-guided fine-needle aspiration biopsy (FNAB), and all the patients had normal thyroid functions. BRFA was performed with a bipolar electrode (CelonProSurge 150-T20) with an output power of 20 W. Nodule volume, thyroid function and clinical symptoms of all the patients were compared before treatment and during follow-up.

RESULTS

In Group A, the BRFA procedures were completed with a mean time of 10.02 ± 3.30 min (range, 5.47-16.03 min) and with a mean total energy deposition of 10.747 ± 3704 J (range, 5510-17.770 J). The procedures were tolerated well in all the patients without causing any major complications. At the 6-month follow-up, all of the nodule volume decreased significantly (from 8.81 ± 8.66 to 1.59 ± 1.55 ml, p < 0.001) in Group A, whereas the nodule volume increased from 6.90 ± 3.77 to 7.87 ± 3.95 ml in Group B (p < 0.001). All (100%) the 35 nodules in Group A had volume reduction ratios (VRRs) of >50%, among which 3 (8.57%) had VRRs >90%. In Group A, the clinical symptoms of the patients who had symptoms before BRFA disappeared, whereas in Group B, the patients had no resolution of clinical symptoms at the 6-month follow-up.

CONCLUSION

Ultrasound-guided percutaneous BRFA seems to be an effective and safe method for the treatment of benign thyroid nodules. It may gain a wide use in clinical practice.

ADVANCES IN KNOWLEDGE

Based on the comparable efficacy and clinical symptoms between the BRFA and untreated groups, the technique of BRFA can be used as an effective and safe method for the treatment of benign thyroid nodules.

Comparison of percutaneous radiofrequency ablation and CyberKnife® for initial solitary hepatocellular carcinoma: A pilot study

AIM: To compare therapeutic outcomes and adverse events in initial solitary hepatocellular carcinoma (HCC) treated with radiofrequency ablation (RFA) and CyberKnife^®.

METHODS: Seventy three consecutive patients with initial solitary HCC treated with RFA (38 patients; RFA group) and CyberKnife^® (35 patients; CK group) were enrolled in this study. Background factors were compared between the two groups. Local and intrahepatic distant recurrence control, and cumulative survival rates were compared between the two groups. These were determined using the Kaplan-Meier method, and the significance of differences was analyzed by log-rank test. The presence of more grade 3 on CTCAE ver. 4.0 early and late adverse events was investigated.

RESULTS: In background factors, age was significantly higher (P = 0.005) and the tumor diameter was significantly larger (P = 0.001) in the CK group. The 1-year local recurrence control rates were 97.4% and 97.1% in the RFA and CK groups, respectively (P = 0.71); the 1-year intrahepatic distant recurrence control rates were 85.6% and 86.1%, respectively (P = 0.91); and the 1-year cumulative survival rates were 100% and 95.2%, respectively (P = 0.075), showing no significant difference in any rate between the two groups. There were no late adverse event in the RFA group, but 11.4% in the CK group had late adverse events. In the CK group, the Child-Pugh score at 12 mo after treatment was significantly higher than that in the RFA group (P = 0.003) and significantly higher than the score before treatment (P = 0.034).

CONCLUSION: The occurrence of adverse events is a concern, but CyberKnife^® treatment is likely to become an important option for local treatment of early HCC.

A case of hepatocellular carcinoma treated by radiofrequency ablation confirming the adjacent major bile duct under hybrid contrast mode through a biliary drainage catheter

Bile duct injury is a potential complication of radiofrequency ablation (RFA). Bipolar RFA devices have recently become available. Because visibility of the bipolar RFA electrodes is not good on ultrasonography, more careful usage of the electrodes to avoid bile ducts is needed. We present a case with hepatocellular carcinoma (HCC) located near the B5 intrahepatic bile duct. To view the bile duct, we used contrast medium for ultrasonography, administered through a biliary drainage catheter for endoscopic nasobiliary drainage (ENBD). Infusing the contrast medium allowed clear visualization of the HCC adjacent to the major bile duct during RFA. We also used a navigation system for bipolar RFA to confirm positions of the electrodes and HCC. We confirmed complete ablation of the HCC while avoiding bile duct injury and late bile duct stenosis. Administration of contrast medium for ultrasonography through an ENBD tube appears useful to avoid bile duct injury during RFA.

A case of small hepatocellular carcinoma treated with laparoscopic multipolar radiofrequency ablation with a no-touch ablation procedure

A 77-year-old man with hepatocellular carcinoma was admitted to our institution. Computed tomography revealed two nodules, one at the surface and one within the liver, ≤3 cm in diameter. We performed laparoscopic radiofrequency ablation using a bipolar system with a "no-touch ablation" procedure using multiple applicators for insertion, not into the tumor directly, but to the perimeter of the tumor. A sufficient ablated area was obtained regardless of tumor location. No operative complications were encountered and adequate therapeutic effect was achieved safely. Laparoscopic multipolar radiofrequency ablation is a feasible procedure for treating hepatocellular carcinoma.