Endoscopic Ultrasound-Guided Radiofrequency Ablation (EUS-RFA) of the Pancreas in a Porcine Model. Gastroenterol Res Pract. 2012;2012:431451. [PMID: 23049547 PMCID: PMC3459266 DOI: 10.1155/2012/431451]

Endoscopic Ultrasound-Guided Radiofrequency Ablation for Pancreatic Adenocarcinoma: A Scoping Review with Meta-Analysis

Background: Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) has recently been proposed as an alternative treatment option for patients with unresectable pancreatic adenocarcinoma (uPDAC) or metastatic pancreatic adenocarcinoma (mPDAC). This review aims to evaluate the technical feasibility, safety, and clinical outcomes of EUS-RFA in treating PDAC, based on the available literature. Methods: Following the PRISMA-DTA guidelines, a comprehensive search of databases, including PubMed, Scopus, and the Cochrane Library, was conducted, focusing on studies reporting on EUS-RFA for PDAC. Articles involving human subjects diagnosed with PDAC and treated with EUS-RFA, written in English, and published up to 30 June 2024, were included. Key outcome measures such as technical success rate, adverse events, tumor response, and patient survival were extracted and analyzed. The review process involved title and abstract screening, followed by full-text review. A meta-analysis was performed for adverse event rates using a random-effects model. Results: We identified 11 studies according to our inclusion criteria, with a total of 137 patients with PDAC. Except for the initial experience with a lower technical success rate due to tumor-related stiffness, all subsequent studies reported a pooled success rate of 100%. Most studies referred to locally advanced or metastatic PDAC, while one reported EUS-RFA in resectable PDAC. A meta-analysis for adverse events was performed, indicating a pooled adverse event rate of 22.6% (95% confidence interval: 0.16-0.30), with the most common adverse event being mild abdominal pain. Severe complications were rare. One study reported a median progression-free survival (PFS) of 16.3 months. Overall survival and PFS were scarcely reported, with median overall survival ranging from 12 to 24 months, inferior to that of the standard approach for uPDAC consisting of neoadjuvant chemoradiotherapy followed by surgery. Conclusions: EUS-RFA is a technically feasible and safe procedure for treating uPDAC or mPDAC and is under investigation for use in resectable PDAC. Even though the short-term outcomes are encouraging, larger cohort studies are necessary to understand long-term efficacy and survival benefits, including progression-free survival.

Reducing the incidence of pancreatic cancer through radiofrequency ablation of mucinous cystic neoplasms: What is the evidence?

Pancreatic cystic lesions are mostly discovered incidentally during cross-sectional imaging for other indications. They range from benign cysts to premalignant lesions, posing a risk for development of pancreatic cancer. Surveillance of cysts with low-risk features and surgical resection of high-risk ones has been the standard of care. However, the lack of consensus between national society guidelines results in discordant management and follow-up. One of the upcoming therapeutic modalities for pancreatic cysts, including mucinous cystic neoplasms (MCN), is endoscopic ultrasound (EUS)-guided interventions, including injection of chemotherapeutic agents or EUS-guided radiofrequency ablation (EUS-RFA). EUS-RFA is emerging as a promising minimally invasive tool with the need for further investigation to understand its clinical utility. This review discusses the physiology, clinical studies, adverse events, and future perspectives of RFA for various pancreatic lesions, with particular regard with MCN.

Comparative efficacies and safeties of cylindrical interstitial laser ablation and radiofrequency ablation on swine pancreas

Laser ablation (LA) has been evaluated for the minimally invasive thermal treatment of various cancers, but conventional unidirectional endoscopic ultrasound (EUS)-guided LA has limitations. Therefore, we developed a cylindrical laser diffuser to overcome the limitations of unidirectional EUS-guided LA. The purpose of this study was to compare the efficacies and safeties of EUS-guided LA using a novel cylindrical laser diffuser and radiofrequency ablation (RFA) in vivo in swine pancreas. EUS-guided RFA (15 W, 30 s, 450 J) and cylindrical interstitial LA (CILA) (5 W, 90 s, 450 J) were applied to normal pancreatic tissue in six anesthetized pigs (three per group). Laboratory tests were performed at baseline, immediately after ablation (day 0), and 2 days after procedures (day 2). Two days after procedures, all pigs were sacrificed, and histopathological safety and efficacy assessments were performed. Technically, EUS-guided RFA and CILA were performed successfully in all cases. No major complications, including perforation or acute pancreatitis, occurred during the experiment in either group. All animals remained in excellent condition throughout the experimental period, and laboratory tests provided no evidence of a major complication. Average necrotic volumes in the RFA and CILA groups were 424.2 mm3 and 3747.4 mm3, respectively, and average necrotic volume was significantly larger in CILA group (p < 0.001). EUS-guided RFA and CILA had acceptable safety profiles in the normal swine pancreas model. Our findings indicate EUS-guided CILA has potential for the effective local treatment of pancreatic cancer as an alternative to EUS-guided RFA.

Endoscopic ultrasound-guided radiofrequency ablation of pancreatic insulinoma: a state of the art review

INTRODUCTION

Insulinomas are the most common functional pancreatic neuroendocrine tumors (PNETs) that lead to incapacitating hypoglycemia. Guidelines recommend surgical resection as the mainstay of management. However, surgery is fraught with complications, causing significant peri/post-operative morbidity. Since insulinomas are usually benign, solitary, small (<2 cm), and do not need lymphadenectomy, hence, in this regard, endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) is now being increasingly performed, to circumvent these adverse events and impairment of pancreatic function.

AREAS COVERED

A comprehensive literature search was undertaken across various databases (PubMed/MEDLINE, Embase, Scopus), with no language restriction, for relevant articles (case series, reviews, case reports) pertaining to EUS-RFA for insulinoma and PNETs, till October 2023. In this review, we have explicated the role of EUS-RFA for insulinoma management, detailing thoroughly its mechanism of action, EUS-RFA devices with data on its safety and efficacy, and an algorithmic approach for its management.

EXPERT OPINION

EUS-RFA is being advocated as a 'mini-invasive' option with the potential to replace surgery as a first-line approach for benign, sporadic, solitary, and small (<2 cm) insulinomas. Under real-time guidance, EUS-RFA has immense precision, is safe, predictable, with acceptable safety profile. Presently, it is being frequently performed for high-risk or inoperable candidates. Current need-of-the-hour is a randomized controlled trial to substantiate its role in the therapeutic algorithm for insulinoma management.

Safety and efficacy of endoscopic ultrasound-guided radiofrequency ablation for pancreatic insulinoma: A single-center experience

BACKGROUND/OBJECTIVES

Insulinomas are rare, functioning pancreatic neuroendocrine neoplasms (pNEN), whose gold standard therapy is surgical resection. Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) is a recent technique that has emerged as a minimally invasive therapeutic option for patients with pancreatic lesions not eligible for surgery. In this study, we aimed to describe a series of patients with unresectable pancreatic insulinoma treated with EUS-RFA.

METHODS

This is a single-center, retrospective study including all consecutive patients with functioning pancreatic insulinoma undergoing EUS-RFA for surgical unfitness or surgery refusal, between March 2017 and September 2021. Technical success (i.e., complete mass ablation), adverse event rate and severity, clinical and radiologic outcomes (i.e., symptom remission with a normal concentration of blood glucose, and the presence of intralesional necrosis), and post-procedural follow-up were assessed.

RESULTS

A total of 10 patients (mean age: 67.1 ± 10.1years; F:M 7:3) were included. The mean size of insulinoma was 11.9 ± 3.3 mm. Technical success and clinical remission were achieved in 100% of patients. Only one (10%) patient was successfully treated with two RFA sessions. Two procedure-related early adverse events occurred, including two (20%) cases of mild abdominal pain. No major complications were observed. The complete radiologic response within 3 months after EUS-RFA was observed in all patients (100%). After a median follow-up of 19.5 (range12-59) months, symptom remission and persistent euglycemia were assessed in all the patients.

CONCLUSIONS

Data from this case series suggest that EUS-RFA is a feasible and safe therapeutic approach for pancreatic insulinomas in patients unwilling or unable to undergo surgery with medium-term efficacy.

Role of Therapeutic Endoscopic Ultrasound in Management of Pancreatic Cancer: An Endoscopic Oncologist Perspective

Pancreatic cancer is a highly lethal disease with an aggressive clinical course. Patients with pancreatic cancer are usually asymptomatic until significant progression of their disease. Additionally, there are no effective screening guidelines for pancreatic cancer in the general population. This leads to a delay in diagnosis and treatment, resulting in poor clinical outcomes and low survival rates. Endoscopic Ultrasound (EUS) is an indispensable tool for the diagnosis and staging of pancreatic cancer. In the modern era, with exponential advancements in technology and device innovation, EUS is also being increasingly used in a variety of therapeutic interventions. In the context of pancreatic cancer where therapies are limited due to the advanced stage of the disease at diagnosis, EUS-guided interventions offer new and innovative options. Moreover, due to their minimally invasive nature and ability to provide real-time images for tumor localization and therapy, they are associated with fewer complication rates compared to conventional open and laparoscopic approaches. In this article, we detail the most current and important therapeutic applications of EUS for pancreatic cancer, namely EUS-guided Fine Needle Injections, EUS-guided Radiotherapy, and EUS-guided Ablations. Furthermore, we also discuss the feasibility and safety profile of each intervention in patients with pancreatic cancer to provide gastrointestinal medical oncologists, radiation and surgical oncologists, and therapeutic endoscopists with valuable information to facilitate patient discussions and aid in the complex decision-making process.

Endoscopic Ultrasound-Guided Local Ablative Therapies for the Treatment of Pancreatic Neuroendocrine Tumors and Cystic Lesions: A Review of the Current Literature

Since its emergence as a diagnostic modality in the 1980s, endoscopic ultrasound (EUS) has provided the clinician profound access to gastrointestinal organs to aid in the direct visualization, sampling, and subsequent identification of pancreatic pathology. In recent years, advancements in EUS as an interventional technique have promoted the use of local ablative therapies as a minimally invasive alternative to the surgical management of pancreatic neuroendocrine tumors (pNETs) and pancreatic cystic neoplasms (PCNs), especially for those deemed to be poor operative candidates. EUS-guided local therapies have demonstrated promising efficacy in addressing a spectrum of pancreatic neoplasms, while also balancing local adverse effects on healthy parenchyma. This article serves as a review of the current literature detailing the mechanisms, outcomes, complications, and limitations of EUS-guided local ablative therapies such as chemical ablation and radiofrequency ablation (RFA) for the treatment of pNETs and PCNs, as well as a discussion of future applications of EUS-guided techniques to address a broader scope of pancreatic pathology.

Efficacy and Safety of Endoscopic Ultrasound-Guided Radiofrequency Ablation for Pancreatic Neuroendocrine Tumors: A Systematic Review and Metanalysis

Introduction: The development of dedicated endoscopes and the technical evolution of endoscopic ultrasound (EUS) have allowed a direct approach to pancreatic neoplastic lesions both for diagnosis and treatment. Among the more promising targets are pancreatic neuroendocrine tumors (Pan-NETs). Aim: to describe the evolution of endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) with particular attention to the treatment of PanNETs, focusing on safety and clinical efficacy of the technique. Methods: MEDLINE, Scopus, and Cochrane Library databases were searched for studies reporting about EUS-RFA for the treatment of PanNETs. Studies with outcomes of interest were selected and results were reported to describe clinical success, complications, fol-low-ups, and electrodes used. Clinical success was defined as the disappearance of clinical symp-toms for functional (F-) PanNETs and as complete ablation per nonfunctional (NF)-PanNETs. The pooled data were analyzed by a random-effects model. Results: Nineteen studies were selected, including 183 patients (82 males, 44.8%) with 196 lesions (101 F-PanNETs and 95 NF-PanNETs). Pooled estimates for the overall AE rates for the clinical efficacy were 17.8% (95% CI 9.1-26.4%) and 95.1% (95% CI 91.2-98.9%) for F-PanNETs and 24.6% (95% CI 7.4-41.8%) and 93.4% (95% CI 88.4-98.4%) for NF-PanNETs. Conclusions: EUS-RFA appears to be a mini-invasive technique with a good safety and efficacy profile for the treatment of F- and NF-PanNETs. EUS-RFA could be of-fered as possible alternative to surgery for the treatment of low-grade NF- or F-PanNETs, especially for those patients that are not eligible or are at high-risk for surgery.

A Review on Endoscopic Ultrasound-Guided Radiofrequency Ablation (EUS-RFA) of Pancreatic Lesions

The morbidity associated with pancreatectomies limits surgical options for high-risk patients with pancreatic neoplasms that warrant resection. Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) offers a minimally invasive and potentially definitive means to treat pancreatic neuroendocrine tumors and precancerous pancreatic cystic lesions. In addition, EUS-RFA may play a role in the treatment and palliation of non-surgical cases of pancreatic adenocarcinoma. The efficacy of RFA appears to be further enhanced by systemic immunomodulatory effects. Here, we review current studies on the developing role of EUS-RFA in these pancreatic pathologies.

Endoscopic ultrasound guided radiofrequency ablation for pancreatic tumors: A critical review focusing on safety, efficacy and controversies

The role of endoscopic ultrasound (EUS) in the last two decades has shifted from a diagnostic tool to an important therapeutic tool treating mainly pancreato-biliary disorders. In recent years, its applications for treating pancreatic diseases have broadened, including the implementation of radiofrequency ablation (RFA), which has been traditionally used for treating solid tumors. In this critical in-depth review, we summarized all the papers throughout the literature regarding EUS-RFA for pancreatic neuroendocrine neoplasms, adenocarcinoma, and pancreatic cystic lesions. Overall, for pancreatic neuroendocrine neoplasms we identified 16 papers that reported 96 patients who underwent EUS-RFA, with acceptable adverse events that were rated mild to moderate and a high complete radiological resolution rate of 90%. For pancreatic adenocarcinoma, we identified 8 papers with 121 patients. Adverse events occurred in 13% of patients, mostly rated mild. However, no clear survival benefit was demonstrated. For pancreatic cystic lesions, we identified 4 papers with 38 patients. The adverse events were mostly mild and occurred in 9.1% of patients, and complete or partial radiological resolution of the cysts was reported in 36.8%. Notably, the procedure was technically feasible for most of the patients. Nevertheless, a long road remains before this technique finds its definite place in guidelines due to several controversies. EUS-RFA for pancreatic tumors seems to be safe and effective, especially for pancreatic neuroendocrine neoplasms, but multicenter prospective trials are needed to consider this treatment as a gold standard.

Endobiliary and Pancreatic Radiofrequency Ablations

Radio frequency ablation (RFA) involves use of thermal energy to perform ablation of tissues. It has a wide range of application in gastrointestinal tract. Over the last few years, several studies have reported successful and safe application in the biliary and pancreatic tissues. It is particularly beneficial in patients with biliary malignancies in whom it has shown to improve survival. Additionally, it can be applied in occluded metal stents secondary to tumor ingrowth to prolong the patency of stents. In pancreas, RFA can successfully ablate cystic lesions and neuroendocrine tumors. It has also been applied in unresectable pancreatic cancers. This review discusses the application of endobiliary and pancreatic RFAs.

Endoscopic Ultrasound-Guided Pancreatic Interstitial Laser Ablation Using a Cylindrical Laser Diffuser: A Long-Term Follow-Up Study

BACKGROUND AND AIMS

Local ablative treatment is another option for improving outcomes and has been evaluated for locally advanced pancreatic cancer. We previously suggested endoscopic ultrasound (EUS)-guided interstitial laser ablation using a cylindrical laser diffuser (CILA) might be a feasible therapeutic option based on experiments performed on pancreatic cancer cell lines and porcine model with a short follow-up (3 days). The aim of this study was to investigate the safety of EUS-CILA performed using optimal settings in porcine pancreas with a long-term follow-up (2 weeks).

METHODS

EUS-CILA (laser energy of 450 J; 5 W for 90 s) was applied to normal pancreatic tissue in porcine (n = 5) under EUS guidance. Animals were observed clinically for 2 weeks after EUS-CILA to evaluate complications. Computed tomography and laboratory tests were carried out to evaluate safety. Two weeks after EUS-CILA, all pigs were sacrificed, and histopathological safety and efficacy evaluations were conducted.

RESULTS

EUS-CILA was technically successful in all five cases. No major complications occurred during the follow-up period. Body weight of porcine did not change during the study period without any significant change in feed intake. Animals remained in excellent condition throughout the experimental period, and laboratory tests and computed tomography (CT) scans provided no evidence of a major complication. Histopathological evaluation showed complete ablation in the ablated area with clear delineation of surrounding normal pancreatic tissue. Mean ablated volume was 55.5 mm² × 29.0 mm and mean ablated areas in the pancreatic sections of the five pigs were not significantly different (p = 0.368).

CONCLUSIONS

In conclusion, our experimental study suggests that EUS-CILA is safe and has the potential to be an effective local treatment modality. No major morbidity or mortality occurred during the study period. Further evaluations are warranted before clinical application.

EUS-RFA of the pancreas: where are we and future directions

Surgical resection remains the gold standard for pancreatic cancer, high-risk pancreatic neuroendocrine tumors (PNETs) and pancreatic cystic neoplasms (PCNs). However, a majority of pancreatic cancers are unresectable at the time of diagnosis. In addition, surgical resection of pancreatic lesions can be associated with morbidity and mortality. A less-invasive alternative therapeutic intervention to avoid short term and long-term adverse events is desirable, as is a minimally-invasive palliative therapy for unresectable or recurrent pancreatic cancers. Endoscopic ultrasound guided radiofrequency ablation (EUS-RFA) allows for selective tissue ablation with minimal injury to the surrounding tissue. EUS-RFA of pancreatic tumors has shown high clinical and technical success with acceptable side effects in pancreatic lesions, lymph nodes, and the celiac plexus. This paper will review the pathophysiology, available technology, safety and efficacy, and future directions of EUS-RFA.

Role of endoscopic ultrasound in anticancer therapy: Current evidence and future perspectives

The digestive system is one of the most common sites of malignancies in humans. Since gastrointestinal tumors represent a massive global health burden both in terms of morbidity and health care expenditures, scientists continuously develop novel diagnostic and therapeutic methods to ameliorate the detrimental effects of this group of diseases. Apart from the well-established role of the endoscopic ultrasound (EUS) in the diagnostic course of gastrointestinal and hepatobiliary malignancies, we have recently become acquainted with a vast array of its therapeutic possibilities. A multitude of previously established, evidence-based methods that might now be guided by the EUS emerged: Radiofrequency ablation, brachytherapy, fine needle injection, celiac plexus neurolysis, and endoscopic submucosal dissection. In this review we endeavored to provide a comprehensive overview of the role of these methods in different malignancies of the digestive system, primarily in the treatment and symptom control in pancreatic cancer, and additionally in the management of hepatic, gastrointestinal tumors, and pancreatic cysts.

Assessment and Modeling of Plasmonic Photothermal Therapy Delivered via a Fiberoptic Microneedle Device Ex Vivo

Plasmonic photothermal therapy (PPTT) has potential as a superior treatment method for pancreatic cancer, a disease with high mortality partially attributable to the currently non-selective treatment options. PPTT utilizes gold nanoparticles infused into a targeted tissue volume and exposed to a specific light wavelength to induce selective hyperthermia. The current study focuses on developing this approach within an ex vivo porcine pancreas model via an innovative fiberoptic microneedle device (FMD) for co-delivering light and gold nanoparticles. The effects of laser wavelengths (808 vs. 1064 nm), irradiances (20-50 mW·mm-2), and gold nanorod (GNR) concentrations (0.1-3 nM) on tissue temperature profiles were evaluated to assess and control hyperthermic generation. The GNRs had a peak absorbance at ~800 nm. Results showed that, at 808 nm, photon absorption and subsequent heat generation within tissue without GNRs was 65% less than 1064 nm. The combination of GNRs and 808 nm resulted in a 200% higher temperature rise than the 1064 nm under similar conditions. A computational model was developed to predict the temperature shift and was validated against experimental results with a deviation of <5%. These results show promise for both a predictive model and spatially selective, tunable treatment modality for pancreatic cancer.

Endoscopic ultrasound-guided ethanol and radiofrequency ablation of pancreatic insulinomas: a systematic literature review

BACKGROUND

Insulinoma is the most common neuroendocrine neoplasm of the pancreas, characterised by hypoglycaemic symptoms. Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) and ethanol ablation (EUS-EA) are novel methods for treating insulinoma.We aimed to perform a systematic review to assess the efficacy and safety of EUS-guided ablation techniques for pancreatic insulinomas.

METHODS

We systematically searched for articles detailing EUS-guided ablations of insulinomas. We performed a qualitative analysis and summarised data on the efficacy and safety of EUS-RFA and EUS-EA techniques.

RESULTS

In total, we identified 35 case reports and case series describing 75 patients with insulinomas treatment with EUS-guided ablation. Twenty-seven patients were treated with EUS-RFA, 47 patients with EUS-EA, and 1 patient received EUS-EA and EUS-RFA in the same session. In total, 84 insulinomas were ablated (EUS-RFA: 31, EUS-EA: 53). Most insulinomas were in the head of the pancreas (40%). The clinical success rate for EUS-guided ablation techniques was 98.5%. The median glucose level was 1.95 (Q1-Q3: 1.69-2.13) mmol/L before ablation compared to 6.20 (Q1-Q3: 5.30-7.05) mmol/L after treatment. The median insulin and C-peptide levels before and after RFA/EA were 230 (Q1-Q2: 120-257) pmol/L and 41 (Q1-Q2 35-42) pmol/L; 2077 (Q1-Q2 1644-2459) pmol/L and 819 (Q1-Q2 696-1072) pmol/L, respectively. There were eleven adverse events: seven abdominal pain, two mild acute pancreatitis, one necrotising acute pancreatitis and one local hematoma. All patients recovered, and there were no periprocedural deaths.

CONCLUSIONS

EUS-guided ablation of insulinoma seems to be a safe and effective treatment and is an alternative to surgical resection in selected cases.

Personalized Approach to the Role of Endoscopic Ultrasound in the Diagnosis and Management of Pancreaticobiliary Malignancies

Pancreaticobiliary malignancies arise from different areas within the pancreas and biliary tree. Endoscopic ultrasound (EUS) is a well-recognized diagnostic and therapeutic modality in the treatment of pancreaticobiliary diseases, and more specifically, pancreaticobiliary malignancies. Traditionally used for diagnostic purposes, EUS plays a critical role in tissue sampling and cancer staging. The emergence of the new field of interventional EUS has allowed EUS to also play a critical role in therapeutic management. Novel interventional EUS procedures such as EUS-guided gastrojejunostomy (EUS-GE), EUS-guided biliary drainage (EUS-BD), and EUS-guided gallbladder drainage (EUS-GLB) can be utilized to treat complications of pancreaticobiliary malignancies such as gastric outlet obstruction, obstructive jaundice, and cholecystitis. In addition, interventional EUS procedures can be utilized for the palliation of unresectable malignancies both for source control with EUS-radiofrequency ablation (EUS-RFA) and for the treatment of abdominal pain refractory to opioid medications with EUS-guided celiac axis neurolysis. However, patient selection remains a critical component in both diagnostic and therapeutic interventions and must be tailored to individual patient wishes, disease pathology, and overall prognosis.

Systematic review of endoscopy ultrasound-guided thermal ablation treatment for pancreatic cancer

The development of curvilinear-array EUS and EUS-guided fine-needle aspiration (EUS-FNA) has led these approaches to become interventional procedures rather than purely diagnostic, as a minimally invasive antitumor therapeutic alternative to radiological and surgical treatments. The possibility to accurately position needle devices and to reach a deep target like the pancreas gland under real-time imaging guidance has expanded the use of EUS to ablate tumors. Currently, a variety of probes specifically designed for EUS ablation are available, including radiofrequency, hybrid cryothermal ablation (combining radiofrequency with cryotechnology), photodynamic therapy, and laser ablation. To date, several studies have demonstrated the safety and feasibility of these ablation techniques in the pancreatic setting, but only a few small series on pancreatic thermal ablation under EUS guidance are available. EUS-guided thermal ablation is primarily used for pancreatic cancer. It is well suited to this disease because of its superior anatomical access compared with other imaging modalities and the dismal prognosis despite improvements in chemoradiotherapy and surgery in the management of pancreatic cancer. Other targets are pancreatic neuroendocrine tumors and pancreatic cystic neoplasms, which are curable by surgical resection, but some patients are poor surgical candidates or prefer conservative management. This is a literature review of previously published clinical studies on EUS-guided thermal ablative therapies. Data on the long-term efficacy of EUS-guided antitumor thermal ablation therapy and large prospective randomized studies are still needed to confirm the real clinical benefits of these techniques for the management of pancreatic neoplasms.

Endoscopic ultrasound-guided ablation of pancreatic cystic neoplasms: ready for prime time?

With the increase in the use of cross-sectional diagnostic imaging, there has been a concomitant rise in the rate of detected pancreatic cystic lesions. Recent years have seen the rise of newly developed therapeutic modalities to treat pancreatic lesions via ablation. Specifically, through the use of endoscopic ultrasound-guided therapy, endoscopists can potentially ablate these lesions safely and with minimally invasive techniques. In this manuscript we review 4 major endoscopic ultrasound-guided ablative therapies: radiofrequency ablation, ethanol injection, chemo ablation, and cryoablation. We also review the efficacy and safety of these techniques and future directions in the management of cystic pancreatic lesions.

Thermal ablation of pancreatic cancer: A systematic literature review of clinical practice and pre-clinical studies

PURPOSE

Pancreatic cancer is a challenging malignancy with low treatment option and poor life expectancy. Thermal ablation techniques were proposed as alternative treatment options, especially in advanced stages and for unfit-for-surgery patients. This systematic review describes the thermal ablative techniques -i.e., Laser (LA), Radiofrequency (RFA), Microwave (MWA) Ablation, High-Intensity Focused Ultrasound (HIFU) and cryoablation- available for pancreatic cancer treatment. Additionally, an analysis of the efficacy, complication rate and overall survival for each technique is conducted.

MATERIAL AND METHODS

This review collects the ex vivo, preclinical and clinical studies presenting the use of thermal techniques in the pancreatic cancer treatment, searched up to March 2018 in PubMed and Medline. Abstracts, letters-to-the-editor, expert opinions, reviews and non-English language manuscripts were excluded.

RESULTS

Sixty-five papers were included. For the ex vivo and preclinical studies, there are: 12 records for LA, 8 for RFA, 0 for MWA, 6 for HIFU, 1 for cryoablation and 3 for hybrid techniques. For clinical studies, 1 paper for LA, 14 for RFA, 1 for MWA, 17 for HIFU, 1 for cryoablation and 1 for hybrid techniques.

CONCLUSIONS

Important technological advances are presented in ex vivo and preclinical studies, as the real-time thermometry, nanotechnology and hybrid techniques to enhance the thermal outcome. Conversely, a lack of standardization in the clinical employment of the procedures emerged, leading to contrasting results on the safety and feasibility of some analyzed techniques. Uniform conclusions on the safety and feasibility of these techniques for pancreatic cancer will require further structured investigation.

Optimization of an Endoscopic Radiofrequency Ablation Electrode

Radiofrequency ablation (RFA) is an increasingly used, minimally invasive, cancer treatment modality for patients who are unwilling or unable to undergo a major resective surgery. There is a need for RFA electrodes that generate thermal ablation zones that closely match the geometry of typical tumors, especially for endoscopic ultrasound-guided (EUS) RFA. In this paper, the procedure for optimization of an RFA electrode is presented. First, a novel compliant electrode design is proposed. Next, a thermal ablation model is developed to predict the ablation zone produced by an RFA electrode in biological tissue. Then, a multi-objective genetic algorithm is used to optimize two cases of the electrode geometry to match the region of destructed tissue to a spherical tumor of a specified diameter. This optimization procedure is then applied to EUS-RFA ablation of pancreatic tissue. For a target 2.5 cm spherical tumor, the optimal design parameters of the compliant electrode design are found for two cases. Cases 1 and 2 optimal solutions filled 70.9% and 87.0% of the target volume as compared to only 25.1% for a standard straight electrode. The results of the optimization demonstrate how computational models combined with optimization can be used for systematic design of ablation electrodes. The optimization procedure may be applied to RFA of various tissue types for systematic design of electrodes for a specific target shape.

Intratumoral radiofrequency hyperthermia-enhanced direct chemotherapy of pancreatic cancer

Purpose

To investigate the technical feasibility of using ultrasound-guided intratumoral radiofrequency hyperthermia (RFH) to enhance local chemotherapy of rat orthotopic pancreatic cancers.

Materials and Methods

Orthotopic pancreatic cancer masses were established by inoculating luciferase/mCherry labeled-pancreatic cancer cells into the pancreatic tails of Lewis model rats via a laparotomy approach. Twenty-four rats with pancreatic cancer and 24 mice with subcutaneous pancreatic cancer xenografts in four study groups (n = 6/group) received various treatments: i) combination therapy of intratumoral MR imaging-heating-guidewire-mediated RFH (42^oC) plus local chemotherapy (gemcitabine); ii) intratumoral chemotherapy alone; iii) RFH alone; and (iv)phosphate-buffered saline (PBS). Transcutaneous ultrasound imaging was used to guide the treatment and subsequently follow changes in tumor sizes. Bioluminescence optical imaging was performed to follow photon signal changes. Sonographic and optical findings were correlated with histology at 14 days.

Results

Optical imaging demonstrated a significantly decreased bioluminescence signal in mice with combination therapy group, compared with the other control groups (0.51±0.18 VS 1.6±0.4 VS 3.18±0.9 VS 3.5±0.96, p < 0.05). Ultrasound imaging showed the smallest tumor volumes of both mice and rat group with the combination therapy, compared with other control groups (0.62±0.16 VS 1.25±0.19 VS 2.28±0.25 VS 2.64±0.26, p < 0.05) and (0.75±0.18 VS 1.31±0.30 VS 1.61±0.28 VS 1.72±0.28, p < 0.05). Both imaging findings were confirmed by histologic correlation.

Conclusion

Intratumoral RFH can augment the chemotherapeutic effect in an orthotopic pancreatic cancer model.

Endoscopic ultrasound-guided radiofrequency ablation in gastroenterology: New horizons in search

Radiofrequency ablation (RFA) has been widely used for the treatment of various solid organ malignancies. Over the last decade, endosonographers have gradually shifted the application of RFA from porcine models to humans to treat a spectrum of diseases. RFA is performed in patients with pancreatic carcinoma who are not candidates for surgery. In this paper, we will discuss various indications for RFA, its procedural details and complications. At present, endoscopic ultrasound-guided RFA is gradually incorporated into the management of various diseases and opens a new avenue for disease treatment.

Endoscopic Management of Pancreatic Cysts

Management of pancreatic cystic lesions relies on patients' clinical presentation, imaging, and endoscopic ultrasound. Current research in basic science, radiology, and endoscopy is evolving and making progress in this condition which is relatively common in the general population. This review focuses on the recent endoscopic ultrasound approaches to the diagnosis of these pancreatic disorders.

Endoscopic Radiofrequency Ablation of the Pancreas

Radiofrequency ablation (RFA) is a well-established technique to ablate dysplastic and neoplastic tissue via local thermal coagulative necrosis. Despite the widespread use in management of several cancers, the application of RFA in pancreas has been limited due to the increased risks of complications from the increased sensitivity of pancreatic tissue to thermal injury and proximity to vascular and biliary structures. RFA has been successfully used during laparotomy for locally advanced pancreatic carcinoma but requires an invasive approach. Endoscopic ultrasound-guided RFA offers the best combination of excellent visualization, real-time imaging guidance, and precise localization with minimal invasiveness. Several animal and human studies have demonstrated the technical feasibility and safety of endoscopic RFA in the pancreas. This article provides a comprehensive review of endoscopic RFA in the management of pancreatic lesions.

Echoendoscopic ablative therapy for solid pancreatic tumors

Initially, endoscopic ultrasound (EUS) was developed to inspect the pancreas and other organs adjacent to the gastrointestinal tract. After introduction of curvilinear-array echoendoscopes, EUS has been used for a variety of interventions in gastroenterology, including fine needle aspiration, pancreatobiliary drainage and tumor ablation. EUS-guided ablation of pancreatic cystic tumors with ethanol and with or without cytotoxic agents has been studied, showing its potential to become an alternative to surgery. However, only few attempts at using ethanol ablation to treat solid pancreatic tumors have been reported. Recently, EUS-guided radiofrequency ablation was introduced and has been cautiously applied for pancreatic cancer. This article focuses on the clinical application of EUS for the ablation of solid pancreatic tumors.

Endoscopy-guided ablation of pancreatic lesions: Technical possibilities and clinical outlook

Endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP)-guided ablation procedures are emerging as a minimally invasive therapeutic alternative to radiological and surgical treatments for locally advanced pancreatic cancer (LAPC), pancreatic neuroendocrine tumours (PNETs), and pancreatic cystic lesions (PCLs). The advantages of treatment under endoscopic control are the real-time imaging guidance and the possibility to reach a deep target like the pancreas. Currently, radiofrequency probes specifically designed for ERCP or EUS ablation are available as well as hybrid cryotherm probe combining radiofrequency with cryotechnology. To date, many reports and case series have confirmed the safety and feasibility of that kind of ablation technique in the pancreatic setting. Moreover, EUS-guided fine-needle injection is emerging as a method to deliver ablative and anti-tumoral agents inside the tumuor. Ethanol injection has been proposed mostly for the treatment of PCLs and for symptomatic functioning PNETs, and the use of gemcitabine and paclitaxel is also interesting in this setting. EUS-guided injection of chemical or biological agents including mixed lymphocyte culture, oncolytic viruses, and immature dendritic cells has been investigated for the treatment of LAPC. Data on the long-term efficacy of these approaches, and large prospective randomized studies are needed to confirm the real clinical benefits of these techniques for the management of pancreatic lesions.

Thermal ablation of pancreatic cyst with a prototype endoscopic ultrasound capable radiofrequency needle device: A pilot feasibility study

BACKGROUND AND OBJECTIVES

Pancreatic cysts are evaluated by endoscopic ultrasound and fine needle aspiration (EUS). The only accepted treatment is pancreatectomy, which is associated with morbidity and mortality. This study evaluated the optimal thermal dosimetry of a novel radiofrequency ablation device using a standard electrosurgical unit in ex vivo cyst models.

METHODS

A modified EUS 22-gauge monopolar needle prototype with a tip electrode connected to a standard electrosurgical unit (Erbe USA, Marietta, GA, USA) was used to induce a subboiling point temperature. A cyst model was created using 2-cm sections of porcine small intestine ligated and filled with saline. After ablation, the cyst models were prepared for pathological evaluation. The epithelial layers were measured in at least two different sites with a micrometer and compared with the corresponding control sample.

RESULTS

Thirty-two cyst models were ablated with maximum temperatures of 50°C, 60°C, 90°C, and 97°C in 8, 11, 11, and 2 cysts, respectively. Longer ablation times were required to induce higher temperatures. A trend in the reduction in thickness of the measured layers was observed after exposure to higher temperatures. A temperature over 50°C was required for the ablation of the muscularis, submucosa, and villi, and over 60°C was required to ablate the mucosal crypts.

CONCLUSIONS

In a preclinical model, a novel radiofrequency EUS-capable needle connected to a standard electrosurgical unit using standard low-voltage coagulation provided ablation in a temperature-dependent fashion with a threshold of at least 60°C and a safe cyst margin below 97°C. This potentially will allow low-cost, convenient cyst ablation.

Review of endoscopic radiofrequency in biliopancreatic tumours with emphasis on clinical benefits, controversies and safety

Most pancreatic cancers and extrahepatic cholangiocarcinomas are unresectable at the time of diagnosis, and even in case of a resectable cancer, for elderly or patients with coexistent comorbidities, surgery is not an option. Current treatment alternatives in these scenarios are very limited. Biliary stenting with self-expanding metal stents (SEMS) is the mainstay palliative treatment of biliary obstruction due to unresectable pancreatic cancer or cholangiocarcinoma. Nevertheless, more than 50% of SEMS become occluded after 6 mo due to tumour over- and ingrowth, leading to hospital readmissions and reinterventions that significantly impair quality of life. Regimes of chemotherapy or chemoradiotherapy also provide minimal survival benefits. Therefore, novel therapies are eagerly awaited. Radiofrequency (RF) energy causes coagulative necrosis leading to local destruction of the accessed malignant tissue and has an established role in the treatment of malignancies in several solid organs, especially liver cancers. However, pancreatic and extrahepatic biliary cancers are not easily accessed by a percutaneous route, making the procedure dangerous. Over the past five years, the development of dedicated devices compatible with endoscopic instruments has offered a minimally invasive option for RF energy delivery in biliopancreatic cancers. Emerging experience with endoscopic RF ablation (RFA) in this setting has been reported in the literature, but little is known about its feasibility, efficacy and safety. A literature review makes it clear that RFA in biliopancreatic tumours is feasible with high rates of technical success and acceptable safety profile. Although available data suggest a benefit of survival with RFA, there is not enough evidence to draw a firm conclusion about its efficacy. For this reason, prospective randomized trials comparing RFA with standard palliative treatments with quality-of-life and survival endpoints are required. Anecdotal reports have also highlighted a potential curative role of RFA in small pancreatic tumours and benign conditions, such as ductal extension of ampullomas, intrahepatic adenomas or non-tumoural biliary strictures. These newest indications also deserve further examination in larger series of studies.

Interventional Therapy for Pancreatic Cancer

BACKGROUND

Palliative therapy and primarily chemoradiotherapy are the mainstream treatments in patients with locally advanced or metastatic pancreatic cancer (PC). Conventional endoscopy and endoscopic ultrasound (EUS)-guided interventional therapy has emerged as an important procedure for PC management. In this review, the progress in conventional endoscopy and EUS for PC management is discussed.

SUMMARY

For local palliative therapy against PC, EUS-guided fine needle injection (FNI) could deliver different kinds of agents, such as radioactive seeds and fiducials. Although their feasibility and safety have been proven, the long-term efficiency of EUS-FNI is still not established. For pain, EUS-celiac plexus neurolysis (CPN) is effective. However, CPN can only relieve the pain to a limited degree, with short duration. Endoscopy-guided stent placement is the preferred strategy for biliary and duodenal obstruction. Plastic and metal stents are equally effective for the relief of obstructive jaundice. The functional times of metal stents are longer than those of a plastic stent.

KEY MESSAGE

For biliary obstruction, a metal stent is the first choice. The long-term efficiency of EUS-FNI still needs further study.

PRACTICAL IMPLICATIONS

Endoscopy and EUS-guided interventions have gradually become the mainstream method for local treatment of PC due to mini-invasiveness and real-time observation. PC is the second most common gastrointestinal malignancy and the sixth leading cause of cancer mortality in the United States, leading to about 4.0% of all cancer deaths [Siegel et al: CA Cancer J Clin 2014;64:9-29]. The only curative approach for patients with PC is surgical resection, but unfortunately 80-90% of patients have a surgically inoperable disease, with 53% having local metastases at the time of diagnosis [Weinberg et al: Oncology (Williston Park) 2015;29:809-820, 886]. Therefore, palliative therapy and primarily chemoradiotherapy are the mainstream of treatment in patients with locally advanced or metastatic PC. Although overall survival has improved from 6 to 8.5-11 months (some of them even survived for a year or more), the overall survival rate has not improved, and the 5-year survival is less than 4% [Weinberg et al: Oncology (Williston Park) 2015;29:809-820, 886; Greenlee et al: CA Cancer J Clin 2001;51:15-36; Zhang et al: Gastroenterol Res Pract 2016;2016:8962321]. Hence, it is crucial to develop more effective local treatment strategies for tumor tissue and symptom palliation. At present, endoscopy has gradually become the mainstream method for local treatment of gastrointestinal cancer due to mini-invasiveness and real-time observation. Conventional endoscopy can be used to manage the complication caused by PC, including endoscopic biliary stent placement for obstructive jaundice, and duodenal stent placement for duodenal obstruction. In addition, in those cases in whom obstructive jaundice failed to be relieved by endoscopic biliary stent placement, EUS-guided biliary drainage has emerged as an alternative procedure. Furthermore, antitumor agents can be delivered into tumor tissue or celiac plexus directly under interventional EUS guided to manage the tumor or the pain caused by the tumor. In this review, the progress in conventional endoscopy and EUS for PC management is discussed.

Advanced endoscopic ultrasound management techniques for preneoplastic pancreatic cystic lesions

Pancreatic cystic lesions can be benign, premalignant or malignant. The recent increase in detection and tremendous clinical variability of pancreatic cysts has presented a significant therapeutic challenge to physicians. Mucinous cystic neoplasms are of particular interest given their known malignant potential. This review article provides a brief but comprehensive review of premalignant pancreatic cystic lesions with advanced endoscopic ultrasound (EUS) management approaches. A comprehensive literature search was performed using PubMed, Cochrane, OVID and EMBASE databases. Preneoplastic pancreatic cystic lesions include mucinous cystadenoma and intraductal papillary mucinous neoplasm. The 2012 International Sendai Guidelines guide physicians in their management of pancreatic cystic lesions. Some of the advanced EUS management techniques include ethanol ablation, chemotherapeutic (paclitaxel) ablation, radiofrequency ablation and cryotherapy. In future, EUS-guided injections of drug-eluting beads and neodymium:yttrium aluminum agent laser ablation is predicted to be an integral part of EUS-guided management techniques. In summary, International Sendai Consensus Guidelines should be used to make a decision regarding management of pancreatic cystic lesions. Advanced EUS techniques are proving extremely beneficial in management, especially in those patients who are at high surgical risk.

Endoscopic Ultrasound-Guided Radiofrequency Ablation of the Pancreatic Tumors: A Promising Tool in Management of Pancreatic Tumors

Objective. Radiofrequency ablation is a well-established antitumor treatment and is recognized as one of the least invasive therapeutic modalities for pancreatic neoplasm. Endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) delivery can be used to treat both pancreatic cancer and asymptomatic premalignant pancreatic neoplasms and may serve as a less invasive alternative to surgical resection. This is an appealing option that may result in less morbidity and mortality. The aim of this review was to summarize and evaluate the clinical and technical effectiveness of EUS-guided RFA of pancreatic neoplasms. Methods. A through literature review was performed to identify the studies describing this novel technique. In this review article, we have summarized human case series. The indications, techniques, limitations, and complications reported are discussed. Results. A total of six studies were included. Overall, a 100% technical success rate was reported in human studies. Complications related to endoscopic ultrasound-guided radiofrequency ablation delivery have been described; however, few cases have presented life-threatening outcomes. Conclusion. We believe that this novel technique can be a safe and effective alternative approach in the management of selected patients.

Interventional Nanotheranostics of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for over 90% of all pancreatic cancer. Nanoparticles (NPs) offer new opportunities for image-guided therapy owing to the unique physicochemical properties of the nanoscale effect and the multifunctional capabilities of NPs. However, major obstacles exist for NP-mediated cancer theranostics, especially in PDAC. The hypovascular nature of PDAC may impede the deposition of NPs into the tumor after systemic administration, and most NPs localize predominantly in the mononuclear phagocytic system, leading to a relatively poor tumor-to-surrounding-organ uptake ratio. Image guidance combined with minimally invasive interventional procedures may help circumvent these barriers to poor drug delivery of NPs in PDAC. Interventional treatments allow regional drug delivery, targeted vascular embolization, direct tumor ablation, and the possibility of disrupting the stromal barrier of PDAC. Interventional treatments also have potentially fewer complications, faster recovery, and lower cost compared with conventional therapies. This work is an overview of current image-guided interventional cancer nanotheranostics with specific attention given to their applications for the management of PDAC.

Initial experience of EUS-guided radiofrequency ablation of unresectable pancreatic cancer

BACKGROUND AND AIMS

Radiofrequency ablation (RFA) has been used as a valuable treatment modality for various unresectable malignancies. EUS-guided radiofrequency ablation (EUS-RFA) of the porcine pancreas was reported to be feasible and safe in our previous study, suggesting that EUS-RFA may be applicable as an adjunct and effective alternative treatment method for unresectable pancreatic cancer. This study aimed to assess the technical feasibility and safety of EUS-RFA for unresectable pancreatic cancer.

METHODS

An 18-gauge endoscopic RFA electrode and a radiofrequency generator were used for the procedure. The length of the exposed tip of the RFA electrode was 10 mm. After insertion of the RFA electrode into the mass, the radiofrequency generator was activated to deliver 20 to 50 W ablation power for 10 seconds. Depending on tumor size, the procedure was repeated to sufficiently cover the tumor.

RESULTS

EUS-RFA was performed successfully in all 6 patients (median age 62 years, range 43-73 years). Pancreatic cancer was located in the head (n = 4) or body (n = 2) of the pancreas. The median diameter of masses was 3.8 cm (range 3cm-9cm). Four patients had stage 3 disease, and 2 patients had stage 4 disease. After the procedure, 2 patients experienced mild abdominal pain, but there were no other adverse events such as pancreatitis or bleeding.

CONCLUSIONS

EUS-RFA could be a technically feasible and safe option for patients with unresectable pancreatic cancer.

EUS-guided radiofrequency ablation for management of pancreatic insulinoma by using a novel needle electrode (with videos)

BACKGROUND AND AIMS

Insulinomas are one of the most common functional pancreatic neuroendocrine tumors. Surgical removal is the standard of care. Patients unfit for or refusing surgery need an alternative nonsurgical method to alleviate symptoms. EUS has been used to localize, aspirate, and tattoo insulinomas and to inject alcohol for local ablation. This study is aimed at assessing the feasibility of EUS-guided radiofrequency ablation (EUS-RFA) for managing patients with a symptomatic insulinoma by using a novel EUS-RFA needle electrode.

METHODS

The EUS-RFA system used consists of a prototype 19-gauge needle electrode, generator, and internal cooling system. EUS-guided RFA is performed under real-time visualization at 50 W to ablate pancreatic insulinomas.

RESULTS

In this observational human case series from a tertiary care center, 3 patients with a symptomatic pancreatic insulinoma, not eligible for surgery, underwent EUS-RFA by using an internally cooled prototype needle electrode. All had rapid symptom relief with biochemical improvement and remained symptom free at 11 to 12 months of follow-up. There were no procedure-related adverse events.

CONCLUSIONS

EUS-RFA with the novel device can be considered in select patients with a symptomatic pancreatic insulinoma based on preliminary findings of a beneficial effect without adverse events. Assessment of the safety profile requires larger prospective trials.

Endoscopic ultrasound-guided radiofrequency ablation of the pancreas: An experimental study with pathological correlation

Background:

The treatment of pancreatic cancer represents a major objective in clinical research, as it still remains the fourth leading cause of cancer deaths among men and women, with approximately 6% of all cancer-related deaths.

Materials and Methods:

We studied the assessment of an endoscopic ultrasound (EUS)-guided radiofrequency ablation (RFA) probe through a 19G needle in order to achieve a desirable necrosis area in the pancreas. Radiofrequency ablation of the head of the pancreas was performed on 10 Yorkshire pigs with a weight between 25 kg and 35 kg and a length of 40-70 cm. Using an EUS-guided RFA experimental probe, we ablated an area of 2-3 cm width. The biological samples were harvested after 3 days and 5 days and necropsy was performed 1 week after the procedure.

Results:

All pigs showed no significant change regarding their behavior and no signs of complication was encountered. Blood analysis revealed increased values of amylase, alkaline phosphatase, and gamma-glutamyl transpeptidase on the 3rd day but a decrease on the 5th day. After necropsy and isolation of the pancreas, the ablated area was easily found, describing a solid necrosis. The pathological examination revealed a coagulative necrosis area with minimal invasion and inflammatory tissue at about 2 cm surrounding the lesion.

Conclusion:

EUS-RFA is a feasible technique and might represent a promising therapy for the future treatment of pancreatic cancer. However, further studies are necessary to investigate EUS-guided RFA as an option for palliation in pancreatic cancer until it can be successfully used in human patients.

Evaluation of radiofrequency ablation using the 1-Fr wire electrode in the porcine pancreas, liver, gallbladder, spleen, kidney, stomach, and lymph nodes: A pilot study

OBJECTIVES

The frequency of detecting asymptomatic incidental lesions of the pancreas is increasing. A substantial number of these lesions are either malignant or premalignant, thus mandating pancreatic resection. A less invasive treatment option may be feasible for selected patients. Endoscopic ultrasound-guided radiofrequency ablation (RFA) may be offered as a treatment option for these patients. The objective of this study was to evaluate the performance characteristics of monopolar RFA using a 1-Fr wire electrode in the porcine pancreas, liver, gallbladder, spleen, kidney, stomach, and lymph nodes.

METHODS

Six Yorkshire pigs were used for this study. The internal organs were accessed after a midline laparotomy. Manual monopolar RFAs were performed over a 90-second period using a wide range of power settings (3, 4, 5, 10, 15, and 25 W). The pancreas was exposed at all power settings; the other organs were exposed at power settings of 3, 4, 5, and 10 W. The maximum diameter of coagulative necrosis was measured.

RESULTS

In all study animals, RFA was performed in the target organs without difficulty. Only the pancreas showed definite coagulative necrosis. The maximum diameter of coagulative necrosis (8.0±1.7 mm) was achieved at 5 W. No definite coagulative necrosis was noted in the other organs.

CONCLUSIONS

Monopolar RFA using a 1-Fr wire electrode resulted in coagulative necrosis in the porcine pancreas. RFA in higher power settings resulted in relatively homogeneous necrosis. At a given power setting, the RFA effect is likely to be differ according to electrical properties of the target tissue. This article is protected by copyright. All rights reserved.

Using the Promise of Sonodynamic Therapy in the Clinical Setting against Disseminated Cancers

Sonodynamic therapy (SDT) is a form of ultrasound therapy in which specialized chemotherapeutic agents known as sonosensitizers are administered to increase the efficacy of ultrasound-mediated preferential damage of neoplastic cells. Multiple in vitro and in vivo studies have indicated that SDT has the ability to exhibit profound physical and chemical changes on cellular structure. As supportive as the data have been, assessment of this method at the clinical level has been limited to only solid tumors. Although SDT has shown efficacy against multiple adherent neoplastic cell lines, it has also shown particular promise with leukemia-derived cell lines. Potential procedures to administer SDT to leukemia patients are heating the appendages as ultrasound is applied to these areas (Heat and Treat), using an ultrasound probe to scan the body for malignant growths (Target and Destroy), and extracorporeal blood sonication (EBS) through dialysis. Each method offers a unique set of benefits and concerns that will need to be evaluated in preclinical mammalian models of malignancy before clinical examination can be considered.

Emerging indications of endoscopic radiofrequency ablation

INTRODUCTION

Radiofrequency ablation (RFA) is a well-validated treatment of dysplastic Barrett's esophagus. Other indications of endoscopic RFA are under evaluation.

RESULTS

Four prospective studies (total 69 patients) have shown that RFA achieved complete remission of early esophageal squamous intra-epithelial neoplasia at a rate of 80%, but with a substantial risk of stricture. In the setting of gastric antral vascular ectasia, two prospective monocenter studies, and a retrospective multicenter study, (total 51 patients), suggest that RFA is efficacious in terms of reducing transfusion dependency. In the setting of chronic hemorrhagic radiation proctopathy, a prospective monocenter study and a retrospective multicenter study (total 56 patients) suggest that RFA is an efficient treatment. A retrospective comparative study (64 patients) suggests that RFA improves stents patency in malignant biliary strictures.

CONCLUSIONS

Endoscopic RFA is an upcoming treatment modality in early esophageal squamous intra-epithelial neoplasia, as well as in gastric, rectal, and biliary diseases.

Endoscopic Ultrasound-Guided Treatment of Pancreatic Cystic and Solid Masses

Pancreatic tumor is one of the most difficult diseases to diagnose and treat because of its anatomical location and characteristics. Recently, there have been several innovative trials on the treatment of pancreatic tumors using endoscopic ultrasound (EUS) because it allows selective access to the difficult to reach target organ along the gastrointestinal tract and can differentiate vessels by color Doppler. Among these trials, several have investigated EUS-guided ethanol lavage with or without paclitaxel for pancreatic cystic tumors. These studies show a 33% to 79% complete resolution rate with a favorable safety profile. Compared to EUS-guided ethanol lavage for pancreatic cystic tumors, EUS-guided radiofrequency ablation is considered a less invasive treatment method for pancreatic cancer. Although there are still several difficulties and concerns about complications, one clinical study reported 72.8% feasibility with favorable safety, and therefore, we anticipate the results of ongoing studies with these new less invasive techniques.

Therapeutic Endoscopic Ultrasound

Endoscopic ultrasound (EUS) technology has evolved dramatically over the past 20 years, from being a supplementary diagnostic aid available only in large medical centers to being a core diagnostic and therapeutic tool that is widely available. Although formal recommendations and practice guidelines have not been developed, there are considerable data supporting the use of EUS for its technical accuracy in diagnosing pancreaticobiliary and gastrointestinal pathology. Endosonography is now routine practice not only for pathologic diagnosis and tumor staging but also for drainage of cystic lesions and celiac plexus neurolysis. In this article, we cover the use of EUS in biliary and pancreatic intervention, ablative therapy, enterostomy, and vascular intervention.

Endoscopic ultrasound guided radiofrequency ablation, for pancreatic cystic neoplasms and neuroendocrine tumors

AIM

To outline the feasibility, safety, adverse events and early results of endoscopic ultrasound (EUS)-radiofrequency ablation (RFA) in pancreatic neoplasms using a novel probe.

METHODS

This is a multi-center, pilot safety feasibility study. The intervention described was radiofrequency ablation (RF) which was applied with an innovative monopolar RF probe (1.2 mm Habib EUS-RFA catheter) placed through a 19 or 22 gauge fine needle aspiration (FNA) needle once FNA was performed in patients with a tumor in the head of the pancreas. The Habib™ EUS-RFA is a 1 Fr wire (0.33 mm, 0.013") with a working length of 190 cm, which can be inserted through the biopsy channel of an echoendoscope. RF power is applied to the electrode at the end of the wire to coagulate tissue in the liver and pancreas.

RESULTS

Eight patients [median age of 65 (range 27-82) years; 7 female and 1 male] were recruited in a prospective multicenter trial. Six had a pancreatic cystic neoplasm (four a mucinous cyst, one had intraductal papillary mucinous neoplasm and one a microcystic adenoma) and two had a neuroendocrine tumors (NET) in the head of pancreas. The mean size of the cystic neoplasm and NET were 36.5 mm (SD ± 17.9 mm) and 27.5 mm (SD ± 17.7 mm) respectively. The EUS-RFA was successfully completed in all cases. Among the 6 patients with a cystic neoplasm, post procedure imaging in 3-6 mo showed complete resolution of the cysts in 2 cases, whilst in three more there was a 48.4% reduction [mean pre RF 38.8 mm (SD ± 21.7 mm) vs mean post RF 20 mm (SD ± 17.1 mm)] in size. In regards to the NET patients, there was a change in vascularity and central necrosis after EUS-RFA. No major complications were observed within 48 h of the procedure. Two patients had mild abdominal pain that resolved within 3 d.

CONCLUSION

EUS-RFA of pancreatic neoplasms with a novel monopolar RF probe was well tolerated in all cases. Our preliminary data suggest that the procedure is straightforward and safe. The response ranged from complete resolution to a 50% reduction in size.

Radiofrequency ablation of pancreatic ductal adenocarcinoma: The past, the present and the future

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers with a grim overall 5-year survival rate of 5%. Advances in surgical techniques, critical care, molecular diagnosis, diagnostic imaging, endosonology and adjuvant therapy have improved outcomes; but still more needs to be achieved. There is an urgent need to discover new avenues that may impact survival. Radiofrequency ablation (RFA) has attracted attention as an adjunctive treatment in PDAC. A review of English literature in PubMed was done using the MESH terms for PDAC and RFA. All the articles were reviewed and core information was tabulated for reference. After a comprehensive review of all articles the data was evaluated to discover the role of RFA in PDAC management. Indications, contraindications, feasibility, success rate, safety, complications and impact on survival were reviewed and are discussed further. RFA appears to be an attractive option for non-metastatic locally advanced PDAC. RFA is feasible but has a significant morbidity. At the present time the integration of RFA into the management of pancreatic ductal adenocarcinoma is evolving. It should be considered as having a complimentary role to current standard therapy in the multimodal management care model. It is likely that indications and patient selection for pancreatic RFA will expand.

Endoscopic ultrasound-guided therapies in pancreatic neoplasms

Endoscopic ultrasound (EUS) has evolved from being primarily a diagnostic modality into an interventional endoscopic tool for the management of both benign and malignant gastrointestinal illnesses. EUS-guided therapy has garnered particular interest as a minimally invasive approach for the treatment of pancreatic cancer, a disease often complicated by its aggressive course and poor survival. The potential advantage of an EUS-guided approach revolves around real-time imaging for targeted therapy of a difficult to reach organ. In this review, we focus on EUS-guided therapies for pancreatic neoplasms.