Endoscopic Ultrasound-Guided Direct Intervention for Solid Pancreatic Tumors

Endoscopic Ultrasound-Guided Antitumor Therapy

Endoscopic ultrasound (EUS) has been used for various interventions to manage intra-abdominal lesions. EUS-guided antitumor therapy via delivery of chemotherapeutic agents, energy, and radioactive seeds has advantages of less invasiveness than surgical approaches, and the anatomic proximity allows easy and accurate access to the pancreas. The feasibility of EUS-guided antitumor therapy has been reported both in pancreatic solid and cystic neoplasms, with promising preliminary results. Randomized controlled trials are mandatory to further confirm its role.

Gold Nanoparticles-Mediated Photothermal Therapy of Pancreas Using GATE: A New Simulation Platform

This work presents the first investigation of gold nanorods (GNRs)-based photothermal therapy of the pancreas tumor using the Monte Carlo-based code implemented with Geant4 Application for Emission Tomography (GATE). The model of a human pancreas was obtained by segmenting an abdominal computed tomography (CT) scan, and its physical and chemical properties, were obtained from experimental and theoretical data. In GATE, GNRs-mediated hyperthermal therapy, simple heat diffusion as well as interstitial laser ablation were then modeled in the pancreas tumor by defining the optical parameters of this tissue when it is loaded with GNRs. Two different experimental setups on ex vivo pancreas tissue and GNRs-embedded water were devised to benchmark the developed Monte Carlo-based model for the hyperthermia in the pancreas alone and with GNRs, respectively. The influence of GNRs on heat distribution and temperature increase within the pancreas tumor was compared for two different power values (1.2 W and 2.1 W) when the tumor was exposed to 808 nm laser irradiation and with two different laser applicator diameters. Benchmark tests demonstrated the possibility of the accurate simulating of NPs-assisted thermal therapy and reproducing the experimental data with GATE software. Then, the output of the simulated GNR-mediated hyperthermia emphasized the importance of the precise evaluation of all of the parameters for optimizing the preplanning of cancer thermal therapy. Simulation results on temperature distribution in the pancreas tumor showed that the temperature enhancement caused by raising the power was increased with time in both the tumor with and without GNRs, but it was higher for the GNR-load tumor compared to tumor alone.

Estimation of porcine pancreas optical properties in the 600-1100 nm wavelength range for light-based therapies

This work reports the optical properties of porcine pancreatic tissue in the broad wavelength range of 600–1100 nm. Absorption and reduced scattering coefficients (µ_a and µ_s′) of the ex vivo pancreas were obtained by means of Time-domain Diffuse Optical Spectroscopy. We have investigated different experimental conditions—including compression, repositioning, spatial sampling, temporal stability—the effect of the freezing procedure (fresh vs frozen-thawed pancreas), and finally inter-sample variability. Good repeatability under different experimental conditions was obtained (median coefficient of variation less than 8% and ~ 16% for µ_a and µ_s′, respectively). Freezing–thawing the samples caused an irreversible threefold reduction of µ_s′ and no effect on µ_a. The absorption and reduced scattering spectra averaged over different samples were in the range of 0.12–0.74 cm⁻¹ and 12–21 cm⁻¹ with an inter-sample variation of ~ 10% and ~ 40% for µ_a and µ_s′, respectively. The calculated effective transport coefficient (µ_eff) for fresh pancreatic tissue shows that regions between 800–900 nm and 1050–1100 nm are similar and offer the lowest tissue attenuation in the considered range (i.e., µ_eff ranging from 2.4 to 2.7 cm⁻¹). These data, describing specific light-pancreas interactions in the therapeutic optical window for the first time, provide pivotal information for planning of light-based thermotherapies (e.g., laser ablation) and instruction of light transport models for biophotonic applications involving this organ.

Endoscopic Management of Pancreatobiliary Malignancies

Pancreatobiliary malignancies have poor prognosis, and many patients are inoperable at the time of diagnosis. When surgical resection is impossible, systemic chemotherapy or radiotherapy is traditionally conducted with trial of immunotherapy or gene therapy lately. With the rapid development of endoscopic instruments and accessories in recent years, not only endoscopic early detection, characterization, and staging but also endoscopic palliative management of the pancreatobiliary malignancies is expanding the horizons. Endoscopic management is often preferred due to similar efficacy to surgical management with less morbidity. Here, we review the methodology and treatment outcome of various endoscopic management strategies in pancreatobiliary malignancies including endoscopic complication management, local palliative therapy, endoscopy-assisted therapy, and pain control utilizing endoscopic retrograde cholangiopancreatography or endoscopic ultrasound.

Advanced Endoscopic Techniques for the Diagnosis of Pancreatic Cancer and Management of Biliary and GastricOutlet Obstruction

Following high-quality imaging studies for staging, endoscopic ultrasound examination fine needle aspiration/biopsy is the preferred modality for tissue diagnosis of pancreatic cancer. Endoscopic retrograde cholangiopancreatography with metal stent placement is used for palliation of malignant biliary obstruction. Metal stents can be placed in patients with resectable pancreatic cancer in whom surgery is going to be delayed. For palliation of gastric outlet obstruction, endoscopic enteral stenting is often selected because of its less invasiveness. Endoscopic ultrasound-guided biliary drainage for malignant biliary obstruction or gastrojejunostomy for gastric outlet obstruction are emerging less invasive techniques as compared with palliative surgery.

New Isotopes for the Treatment of Pancreatic Cancer in Collaboration With CERN: A Mini Review

The use of radioactivity in medicine has been developed over a century. The discovery of radioisotopes and their interactions with living cells and tissue has led to the emergence of new diagnostic and therapeutic modalities. The CERN-MEDICIS infrastructure, recently inaugurated at the European Center for Nuclear Research (CERN), provides a wide range of radioisotopes of interest for diagnosis and treatment in oncology. Our objective is to draw attention to the progress made in nuclear medicine in collaboration with CERN and potential future applications, in particular for the treatment of aggressive tumors such as pancreatic adenocarcinoma, through an extensive review of literature. Fifty seven out of two hundred and ten articles, published between 1997 and 2020, were selected based on relevancy. Meetings were held with a multi-disciplinary team, including specialists in physics, biological engineering, chemistry, oncology and surgery, all actively involved in the CERN-MEDICIS project. In summary, new diagnostic, and therapeutic modalities are emerging for the treatment of pancreatic adenocarcinoma. Targeted radiotherapy or brachytherapy could be combined with existing therapies to improve the quality of life and survival of these patients. Many studies are still in the pre-clinical stage but open new paths for patients with poor prognosis.

Diagnostic and Interventional Role of Endoscopic Ultrasonography for the Management of Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (PanNENs) are relatively rare, but their incidence has increased significantly in the last decades. Precise diagnosis and prognostic stratification are crucial for proper patient management. Endoscopic ultrasound (EUS) is the modality of choice for diagnosis of solid pancreatic tumors, showing a higher tumor detection rate than other imaging modalities, especially for small size lesions. EUS also serves as a guide for preoperative sampling and other interventions. EUS-tissue acquisition is a safe and highly accurate technique for cyto/histological diagnosis of PanNENs with a well-demonstrated correlation between Ki-67 proliferation index values and tumor grading on EUS and surgical specimens according to the WHO 2017 classification. Furthermore, the possibility of a preoperative EUS-guided fine needle tattooing or fiducial markers placement may help the surgeon to locate small and deep tumors, thus avoiding formal pancreatic resections in favor of parenchymal-sparing surgery. Finally, locoregional ablative treatments using either ethanol injection or radiofrequency ablation have been proposed in recent studies with promising results in order to control symptoms or reduce tumor burden in selected patients unfit for surgery with functioning or non-functioning PanNENs. This article review highlights the current role of EUS in PanNENs management, focusing on the present and future applications of EUS-guided interventions.

Endoscopic Ultrasound-Guided Fiducial Placement for Stereotactic Body Radiation Therapy in Pancreatic Malignancy

Stereotactic body radiation therapy (SBRT) is an important treatment option for pancreatic cancer, which is known to be one of the malignancies with the worst prognosis. However, the high radiation doses delivered during SBRT may cause damage to adjacent radiosensitive organs. To minimize such damage, fiducial markers are used for localization during SBRT for pancreatic cancer. The development of endoscopic ultrasound (EUS) has enabled fiducial markers to be inserted into the pancreas using an EUS fine-needle aspiration (FNA) needle, unlike in the past when percutaneous placement was generally performed. For successful EUS-guided fiducial marker placement, it is necessary for the fiducial markers to be loaded within the EUS-FNA needles to have a low probability of complications and a low migration risk, and to be stably observed in SBRT imaging. A systematic review has shown that the technical success rate of EUS-guided fiducial marker placement is 96.27%, whereas the fiducial marker migration and adverse event rates are 4.33% and 4.85%, respectively. Nonetheless, standardized techniques for fiducial marker placement and the characteristics of optimal fiducial markers have not yet been established. This review will introduce the characteristics (e.g., materials and shapes) of fiducial markers used in fiducial marker placement for pancreatic cancer and will discuss conventional techniques along with their success rates, difficulties, and adverse events.

Endoscopic retrograde cholangiopancreatography guided interventions in the management of pancreatic cancer

Pancreatic cancer is the leading cause of cancer-related morbidity and mortality with an overall five-year survival of less than 9% in the United States. At presentation, the majority of patients have painless jaundice, pruritis, and malaise, a triad that develops secondary to obstruction, which often occurs late in the course of the disease process. The technical advancements in radiological imaging and endoscopic interventions have played a crucial role in the diagnosis, staging, and management of patients with pancreatic cancer. Endoscopic retrograde cholangiopancreatography (ERCP)-guided diagnosis (with brush cytology, serial pancreatic juice aspiration cytologic examination technique, or biliary biopsy) and therapeutic interventions such as pancreatobiliary decompression, intraductal and relief of gastric outlet obstruction play a pivotal role in the management of advanced pancreatic cancer and are increasingly used due to improved morbidity and complication rates compared to surgical management. In this review, we highlight various ERCP-guided diagnostic and therapeutic interventions for the management of pancreatic cancer.

Necrosis volume and Choi criteria predict the response to endoscopic ultrasonography-guided HybridTherm ablation of locally advanced pancreatic cancer

Background and study aims  Endoscopic ultrasound (EUS)-guided ablation of pancreatic ductal adenocarcinoma (PDAC) with HybridTherm-Probe (EUS-HTP) is feasible and safe, but the radiological response and ideal tool to measure it have not been investigated yet. The aims of this study were to: 1) assess the radiological response to EUS-HTP evaluating the vital tumor volume reduction rate, Response Evaluation Criteria in Solid Tumors (RECIST1.1) and Choi criteria; 2) determine the prognostic predictive yield of these criteria. Patients and methods  A retrospective analysis was performed of patients with locally advanced PDAC after primary treatment or unfit for chemotherapy prospectively treated by EUS-HTP. Computed tomography scan was performed 1 month after EUS-HTP to evaluate: 1) vital tumor volume reduction rate (VTVRR) by measuring necrosis and tumor volumes through a computer-aided detection system; and 2) RECIST1.1 and Choi criteria. Results  EUS-HTP was feasible in 22 of 31 patients (71 %), with no severe adverse events. Median post-HTP survival was 7 months (1 - 35). Compared to pre-HTP tumor volume, a significant 1-month VTVRR (mean 21.4 %) was observed after EUS-HTP ( P  = 0.005). We identified through ROC analysis a VTVRR > 11.46 % as the best cut-off to determine post-HTP 6-month survival outcome (AUC = 0.733; sensitivity = 70.0 %, specificity = 83.3 %). This cut-off was significantly associated with longer overall survival (HR = 0.372; P  = 0.039). According to RECIST1.1 and Choi criteria, good responders to EUS-HTP were 60 % and 46.7 %, respectively. Good responders according to Choi, but not to RECIST1.1, had longer survival (HR = 0.407; P  = 0.04). Conclusions  EUS-HTP induces a significant 1-month VTVRR. This effect is assessed accurately by evaluation of necrosis and tumor volumes. Use of VTVRR and Choi criteria, but not RECIST 1.1 criteria, might identify patients who could benefit clinically from EUS-HTP.

Management of Gastrointestinal Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are derived from neuroendocrine cell system and can have benign or malignant characteristics. They are rare tumors, but have been increasing in incidence over the past 40 years. Patients with NENs may develop symptoms due to primary tumor invasion, metastasis, or from secretion of hormonally active tumor substances. Multiple imaging modalities are used for diagnosis and staging, including specialty scans such as ¹¹¹In pentetreotide (Octreoscan) and ⁶⁸Gallium-DOTATATE, along with endoscopy, endoscopic ultrasound, and biochemical marker testing. Treatment involves both surgical approach, for both primary and metastatic lesions, as well as medical management for symptom management and disease progression. This article will review the current clinical knowledge regarding the diagnosis, treatment, and prognosis of these fascinating neoplasms and the associated hormonal syndromes.

Evaluation of the feasibility of intrapancreatic delivery of drug-loaded microparticles via EUS-guided fine needle injection using a swine model

Background and study aims  Patients with pancreatic cancer often have locally advanced or metastatic disease and are not candidates for curative surgery. Polymer-based microparticles (MPs) represent a drug delivery system that offers sustained release of a chemotherapeutic drug after intralesional injection for local tumor management. The aim of this study was to determine the feasibility of endoscopic ultrasound-guided fine-needle injection (EUS-FNI) of drug-loaded MPs tagged with a fluorophore and fiducial markers for locating the injection site. Secondary aims were to determine the tissue-specific effects of MPs. Methods  Five pigs underwent EUS with selection of an injection site within the pancreas that was marked by placing fiducial markers prior to the MPs injection. EUS-FNI of either blank microparticles (BMPs), containing no drug, or gemcitabine-loaded microparticles (GMPs) was performed. A saline flush containing Spot Endoscopic Marker was used to expel any residual MPs in the needle shaft and tattoo the injection site. Results  A green fluorescent protein flashlight was used to successfully identify the site of MP injection sites in the dissected pancreas. Frozen sections of pig pancreas demonstrated a defined deposit, confirming the delivery of the MPs. Finally, fluorescence microscopy showed activation of caspase-mediated cell death in pancreases of animals that received injections of GMPs. Conclusions  This pilot study demonstrated that fiducial marker placement and pancreatic EUS-FNI of MPs was successful in all pigs with no animals demonstrating pancreatitis. Further studies are needed to determine the role for intralesional injection of drug-loaded MPs in borderline resectable or unresectable pancreatic cancer.

Current Status of Endoscopic Ultrasound Techniques for Pancreatic Neoplasms

Endoscopic ultrasound (EUS) now plays an important role in the management of pancreatic neoplasms. There are various types of pancreatic neoplasms, from benign to malignant lesions, and the role of EUS ranges from the imaging diagnosis to treatment. EUS is useful for the detection, characterization, and tissue acquisition of pancreatic lesions. Recent advancement of contrast-enhanced harmonic EUS and elastography enables better characterization of pancreatic lesions. In addition to these enhanced EUS imaging techniques, EUS-guided tissue acquisition is now the standard procedure to establish the pathological diagnosis of pancreatic neoplasms. While these diagnostic roles of EUS have been established, EUS-guided interventions such as ablation and drainage are also increasingly utilized in the management of pancreatic neoplasms. However, most of these EUS-guided interventions are not yet standardized in terms of techniques and devices and thus need further investigations.

EUS-guided irreversible electroporation using endoscopic needle-electrode in porcine pancreas

BACKGROUND

Endoscopic irreversible electroporation (IRE) can be performed using a flexible, thin, needle-shaped electrode for an endoscopic ultrasound (EUS)-guided procedure. This study aimed to evaluate the feasibility and efficacy of performing EUS-guided IRE with endoscopic needle-electrode in porcine pancreas.

METHODS

Experimental endoscopic IRE on the pancreas were performed by EUS-guided approach in three pigs and compared with surgical approach in three pigs. The animals were killed after 24 h and their pancreases collected.

RESULTS

IRE ablation using endoscopic needle-electrode was successful technically in EUS-guided approaches for the pancreas. Immediately following IRE, the ablated pancreatic tissue showed no gross change except focal hemorrhage. H&E staining presented a well-demarcated ablation site measuring 1.0-1.5 cm in diameter in the pancreas. TUNEL immunohistochemistry showed diffuse cell death along the puncture site 24 h after IRE. No complication was observed in pigs after endoscopic IRE ablation.

CONCLUSION

EUS-guided IRE ablation was feasible and effective for pancreas using the newly developed device.

Future Perspectives on Endoscopic Ultrasonography-Guided Therapy for Pancreatic Neoplasm

Endoscopic ultrasonography (EUS)-guided therapy with ethanol injection or catheter-based radiofrequency ablation for pancreatic neoplasm has been conducted as a potential alternate treatment modality for patients who are not eligible for surgery. On the basis of the limited number of studies available, EUS-guided ablation therapy with the aforementioned methods for small pancreatic neoplasms has demonstrated promising technical feasibility and safety profiles. To be considered as a legitimate alternative option to surgery, however, EUS-guided ablation therapy must provide a long-term efficacy profile along with the consensus among experts regarding its treatment parameter. This review focuses on the clinical issues and future perspectives of EUS-guided therapy for pancreatic neoplasm.

Diagnosis of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are relatively rare; however, the incidence has increased over the last few decades. They are classified as functional or non-functional tumors according to the presence of associated clinical symptoms. The majority are non-functional tumors. For classification and staging, the World Health Organization 2010 classification system is the most commonly accepted. Chromogranin A is the most sensitive marker but has insufficient specificity. In general, PNETs are hypervascular tumors, and multiphasic contrast-enhanced computed tomography is considered the first choice for imaging study. Multiphasic magnetic resonance imaging can detect PNETs smaller than 2 cm and small liver metastasis compared with other modalities. Somatostatin receptor scintigraphy is often used in cases where functional PNETs are suspected. Positron emission tomography (PET) scan with 18F-fluorodeoxyglucose cannot visualize PNETs, but PET with 68-Ga DOTATATE can. Endoscopic ultrasonography can characterize smaller PNETs using contrast and confirm histology through fine needle aspiration or biopsy. In this article, we review the characteristics of grading systems and diagnostic modalities commonly used for PNETs.