EUS-guided investigational therapy for pancreatic cancer

Time-dependent image changes after ethanol injection into the pancreas: an experimental study using a porcine model

Background

Ethanol, a commonly available agent, has been used to successfully ablate cystic and solid lesions in the pancreas. The aim of this study is to investigate the effects of an ethanol injection into the porcine pancreas and observe the time-dependent image changes in the pancreatic parenchyma.

Methods

Pure ethanol was injected into the pancreatic tail using a 25-gauge EUS needle with direct ultrasound guidance under celiotomy: 1 mL and 2 mL were injected, respectively. The abdomen was closed after the injection. MRI was performed before the procedure, immediately after, and on postoperative day (POD) seven. Blood samples were taken before the procedure and on PODs one, three, five, and seven. The pigs were euthanised on POD seven.

Results

Immediately after the injection, linear high signal areas in the pancreatic tail on T2 and rounded speckled high signal areas on DWI images were detected in both animals, measuring 35 × 32 mm in the 1 mL injected pig and 42 × 38mm in the 2 mL injected pig. After POD seven, rounded high signal areas were noted on T2 images, measuring 22 × 18 mm and 36 × 28 mm respectively. On POD one, the 1 mL injected animal had a 53% elevation in serum amylase while the 2 mL injected animal had a 66% elevation. Histologically, cystic and necrotic changes in the parenchyma were observed, measuring 23 × 22 mm and 40 × 35 mm respectively.

Conclusions

Our results, which are limited to normal pancreas, suggested that a 1 mL injection caused localised changes within the pancreas while a 2 mL injection induced more widespread changes beyond the pancreas. The effective area of ethanol was widespread immediately after injection, and then the area was reduced with cystic and necrosis changes.

Rapid on-site cytopathological examination (ROSE) performed by endosonagraphers and its improvement in the diagnosis of pancreatic solid lesions

PURPOSE

To evaluate the diagnosis improvement of EUS-FNA when using ROSE performed by the endosonographer.

METHODS

A retrospective study was conducted. A total of 48 pancreatic solid masses EUS-FNA were divided into two groups according to the availability of on-site cytology (ROSE) - the first 24 patients (group A-without ROSE) and the latter 24 cases (group B-with ROSE). Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, complications and inadequacy rate of EUS-FNA were determined and compared.

RESULTS

Among the 48 EUS-FNA, the overall performance was: sensitivity 82%; specificity 100%; positive predictive value (PPV) 100%; negative predictive value (NPV) 70% and accuracy 87%. The sensitivity of the Group A was 71%, versus 94% in-group B (p=0.61). Moreover, the negative predictive value was 58% versus 87% (p=0.72). The accuracy rate increased from 79% to 96% (p=0.67) in the ROSE group. The number of punctures was similar between the groups. No major complications were reported.

CONCLUSION

Rapid on-site cytopathological examination, even when performed by the endosonographer, may improve the diagnostic performance in the diagnosis of solid pancreatic lesions, regardless of the slight increase in the number of punctures.

Endoscopic ultrasound-guided ethanol injection in the pancreas in a porcine model: a preliminary study

BACKGROUND AND AIM

Despite aggressive multimodal treatments, survival rates for patients with pancreatic cancer remain disappointing. Local progression is problematic, and minimally invasive procedures allowing locoregional control are needed. In this study, we attempted endoscopic ultrasound (EUS)-guided injection of ethanol into the pancreas.

METHODS

Under EUS guidance, pure ethanol (2 mL) was injected into normal tissue of the pancreatic body in two anesthetized domestic pigs. Serum concentrations of amylase, aspartame aminotransferase, alanine aminotransferase, alkaline phosphatase, and lactate dehydrogenase were measured before treatment and at 2 h, 48 h and 2 weeks after injection. Body weight and clinical signs were also observed. After the animals were euthanized, the pancreases were analyzed histologically.

RESULTS

EUS imaging allows real-time surveillance of the injection procedure. Mild diarrhea was noted in one animal, but no other adverse effects were observed. No marked changes in laboratory tests were noted. Histologically, parenchymal necrosis extending over a wide area was seen without severe inflammation.

CONCLUSION

EUS-guided ethanol injection in the pancreas seems to be technically simple. More detailed assessments of the safety and dose-effect relationship issues associated with this procedure are required.

The multidisciplinary management of gastrointestinal cancer. Pancreatic cancer: from pathogenesis to cure

Pancreatic cancer is the fourth leading cause of cancer-related death in the USA. The disease has a high mortality rate and the 5-year survival rate is estimated to be 4%. Currently, surgical resection is only possible in 20% of patients; even then, the overall 5-year survival rate is only 25%. As such, surgical therapy alone is not sufficient for pancreatic carcinoma, and prospective investigation of additional modalities is crucial. Numerous negative trials have shown that chemotherapy alone is the standard of care after resection of pancreatic carcinoma. However, results remain poor and progress with new drugs is needed in this setting. For locally advanced disease, the situation is more complicated; the ideal chemoradiation schedule has not been clearly defined, and improvements could come in the near future from the use of new radiotherapy tools and targeted therapies. For advanced disease, chemotherapy alone has given very disappointing results. A multidisciplinary approach combining biological assessment of targets with clinical trials to evaluate new targeted drugs should be considered.

Endosurgery: what do we need?

A paradigm shift in therapeutic endoscopy occurred with the advent of mucosectomy for the treatment of mucosal neoplasms and suture plication for gastroesophageal reflux disease. The objectives changed from finding simple, easy, and quick alternatives to surgery to reproducing surgical results. A radical version of flexible endoscopy has emerged to meet new goals of full-thickness resections, creation of anastomoses, and lumen reconfiguration. This will require a new generation of endosurgical tools that cut, stitch, and staple with added dimensions of multiaxis orientation and triangulation.

Current medical treatment of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (NETs) consist of a wide group of neoplasms, with different biological behaviors in terms of aggressiveness and hormone production. In the last two decades, significant progress has been observed in our understanding of their biology, diagnosis and treatment. Surgery remains to be the only curative approach, but unfortunately the diagnosis is often delayed due to the slow growth of these tumors and the difficulty in identifying the symptoms related to the tumor-released hormones. In addition to surgery, other approaches to control the disease are biological therapy consisting of somatostatin analogs and interferon (IFN), systemic chemotherapy, radioligand therapy and local therapy with chemoembolization. Several newer cytotoxic agents, including irinotecan, gemcitabine, taxanes, oxaliplatin, capecitabine and PS-341 have been studied in metastatic patients. Considering the high vascularity of these tumors, antiangiogenic agents like endostatin and thalidomide have also been evaluated in advanced NETs. Although these agents seem to have potential activity in NETs and may increase progression free survival, none of these currently available medical therapeutic options are curative. While more efficient novel strategies are to be developed, the rationale use of the current therapeutic options may improve quality of life, control the symptoms related to the hypersecretion of hormones and/or peptides, control tumor proliferation and prolong survival in patients suffering from NETs.

EUS-guided interstitial brachytherapy of the pancreas: a feasibility study

BACKGROUND

Intraoperative interstitial brachytherapy has been effective when used at laparotomy to improve local control in locally advanced pancreatic cancer. Our aim in this study was to investigate the feasibility and the safety of EUS-guided brachytherapy of the pancreas in a porcine model.

METHODS

A modified 18-gauge needle with radioactive seeds was inserted, under EUS guidance, into the pancreas. The radioactive seeds were implanted into the tissue by the needle. After 14 days of clinical observation, the animals were euthanized, and the tissue response to brachytherapy was examined.

OBSERVATIONS

All the seeds were successfully implanted, and no migration occurred. Localized tissue necrosis and fibrosis was achieved in the pancreas, without significant complication. One pig had mild hyperlipasemia. Biochemical parameters were normal in the remaining pigs.

CONCLUSIONS

EUS-guided implantation of radioactive seeds is a safe, simple, and minimally invasive technique for interstitial brachytherapy.

Pancreatic neoplasms

Patients who present with signs and symptoms suggesting a pancreatic neoplasm typically undergo initial imaging with transabdominal ultrasound or CT. When a pancreatic mass or fullness is identified, it may represent an inflammatory mass, benign process, or malignancy. Endoscopic ultrasound (EUS) is performed commonly to further characterize the lesion, obtain a tissue diagnosis, and for staging. This article reviews the role of EUS for the diagnosis and staging of pancreatic tumors.

ENDOSCOPIC ULTRASOUND INSTRUMENTATION, APPLICATIONS IN HUMANS, AND POTENTIAL VETERINARY APPLICATIONS

Endoluminal scanning under endoscopic guidance, or endoscopic ultrasonography (EUS), has become the most significant advance for imaging the gastrointestinal (GI) tract wall and contiguous organs in the past 20 years. It was originally designed to overcome the limitations in humans to imaging the abdominal organs transabdominally, such as large penetration depths and GI air. This imaging modality provides detailed images of pathological processes both within and outside of the GI wall since a high-frequency transducer can be brought into close proximity with the target regions. It has found most success in humans for the staging of lung, gastric, and esophageal cancer, the detection of both lymphatic and hepatic metastases, and diagnosis of pancreatitis and pancreatic cancer, as well as achieving an important role in interventional and therapeutic procedures. The EUS examination can be performed to examine both the thorax and abdomen in animals when both conventional transthoracic or transabdominal ultrasound are inadequate due to intervening air, bone, large penetration depths, or obesity. The echoendoscope is similar to a conventional endoscope but has an ultrasound transducer at its tip. Both radial and linear multifrequency scanners are available. Linear scanners allow fine-needle aspiration (FNA) of the bowel wall or extraluminal structures. Transducer coupling is either by direct mucosal contact or by inflation of a water-filled balloon surrounding the transducer. Current thoracic applications for EUS in veterinary medicine include examination of the mediastinum, bronchial lymph nodes, esophagus, and pulmonary lesions as well as FNA of pulmonary masses. Abdominal applications include examination of both pancreatic limbs and the liver, including portosystemic shunts, detection of lymphadenomegaly, and examination of the gastric wall, duodenum, and jejunum. Other potential applications in dogs and cats include tumor staging and intrapelvic ultrasound.

Endoscopic ultrasonography for the diagnosis of intrathoracic lesions in two dogs

Endoscopic ultrasound was developed initially in humans to overcome limitations of conventional ultrasound in examining certain internal organs due to intervening bone or air-filled structures. Endoscopic ultrasound has been used most widely in investigation of the gastrointestinal tract in humans, but many intrathoracic applications as well as endoscopic ultrasound-guided techniques have recently been described. Mediastinal and pulmonary structures can be examined with endoscopic ultrasound since a high frequency ultrasound probe can be brought into close contact with the areas of interest via a transesophageal approach. The purpose of this report is to describe the application of endoscopic ultrasound as an aid in the diagnosis of intrathoracic disease in the dog. Two dogs, one with a history of prior esophageal foreign body extraction, the other with apathy, weakness and dyspnea were referred for further investigation. Both dogs had caudal intrathoracic soft tissue opacities diagnosed radiographically, but their origin and nature were difficult to determine. Conventional ultrasound was limiting in both dogs due to their location and superimposition of gas-filled structures. With endosonography lesions were characterized more completely. We have found endoscopic ultrasound to be an elegant diagnostic tool for the investigation of radiographically detected intrathoracic lesions in the dog whose origins are difficult to determine or do not lend themselves to investigation by conventional ultrasound. Endoscopic ultrasound provides valuable diagnostic information complementary to that provided radiographically which aids in therapeutic planning. Endoscopic ultrasound was also more sensitive for detecting mediastinal lymphadenomegaly than radiography in one of the dogs. An additional advantage of endoscopic ultrasound is the fact that US-guided tissue sampling can be performed during the examination.

Endoscopic ultrasound: diagnostic and therapeutic applications

Endoscopic ultrasound (EUS) comprises several techniques of performing high-frequency ultrasound via an endoscope placed in the gastrointestinal tract (oesophagus, stomach, duodenum and pancreaticobiliary tree and rectum). It has rapidly become an important tool in the investigation of a variety of lumenal disorders as well as locoregional staging of gastrointestinal malignancies. Needle biopsy of peri-intestinal structures, such as lymph nodes and pancreatic masses, can also be performed under real-time ultrasound control. To date, the utilization of this technology in Australia has been limited by cost constraints and a paucity of training opportunities. EUS continues to be a rapidly growing area in clinical gastroenterology. Recent studies continue to define its role, particularly in the loco-regional staging of a variety of malignancies. In addition, new instruments permit tissue sampling and a variety of therapeutic manoeuvres under direct ultrasound guidance.33; 26-32)