Pancreatic neuroendocrine tumors: clinical features, diagnosis and medical treatment: advances

Contemporary Approaches to the Surgical Management of Pancreatic Neuroendocrine Tumors

The incidence of pancreatic neuroendocrine tumors (PNETs) is on the rise primarily due to the increasing use of cross-sectional imaging. Most of these incidentally detected lesions are non-functional PNETs with a small proportion of lesions being hormone-secreting, functional neoplasms. With recent advances in surgical approaches and systemic therapies, the management of PNETs have undergone a paradigm shift towards a more individualized approach. In this manuscript, we review the histologic classification and diagnostic approaches to both functional and non-functional PNETs. Additionally, we detail multidisciplinary approaches and surgical considerations tailored to the tumor's biology, location, and functionality based on recent evidence. We also discuss the complexities of metastatic disease, exploring liver-directed therapies and the evolving landscape of minimally invasive surgical techniques.

Preoperative pancreatic stent placement before the enucleation of insulinoma located in the head and neck of the pancreas in proximity to the main pancreatic duct: study protocol for a multicentre randomised clinical trial in Chinese tertiary medical centres

INTRODUCTION

The surgical intervention approach to insulinomas in proximity to the main pancreatic duct remains controversial. Standard pancreatic resection is recommended by several guidelines; however, enucleation (EN) still attracts surgeons with less risk of late exocrine/endocrine insufficiency, despite a higher postoperative pancreatic fistula (POPF) rate. Recently, the efficacy and safety of preoperative pancreatic stent placement before the EN have been demonstrated. Thus, a multicentre open-label study is being conducted to evaluate the efficacy and safety of stent placement in improving the outcome of EN of insulinomas in proximity to the main pancreatic duct.

METHODS AND ANALYSIS

This is a prospective, randomised, open-label, superiority clinical trial conducted at multiple tertiary centres in China. The major eligibility criterion is the presence of insulinoma located in the head and neck of the pancreas in proximity (≤2 mm) to the main pancreatic duct. Blocked randomisation will be performed to allocate patients into the stent EN group and the direct EN group. Patients in the stent EN group will go through stent placement by the endoscopist within 24 hours before the EN surgery, whereas other patients will receive EN surgery directly. The primary outcome is the assessment of the superiority of stent placement in reducing POPF rate measured by the International Study Group of Pancreatic Surgery standard. Both interventions will be performed in an inpatient setting and regular follow-up will be performed. The primary outcome (POPF rate) will be tested for superiority with the Χ2 test. The difference in secondary outcomes between the two groups will be analysed using appropriate tests.

ETHICS AND DISSEMINATION

The study has been approved by the Peking Union Medical College Hospital Institutional Review Board (K23C0195), Ruijin Hospital Ethics Committee (2023-314), Peking University First Hospital Ethics Committee (2024033-001), Institutional Review Board of Xuanwu Hospital of Capital Medical University (2023223-002), Ethics Committee of the First Affiliated Hospital of Xi'an Jiaotong University (XJTU1AF2023LSK-473), Institutional Review Board of Tongji Medical College Tongji Hospital (TJ-IRB202402059), Ethics Committee of Tongji Medical College Union Hospital (2023-0929) and Shanghai Cancer Center Institutional Review Board (2309282-16). The results of the study will be published in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT05523778.

[Current views on the treatment of insulinoma]

RELEVANCE

Insulinoma is the most common hormonally active neuroendocrine tumor (NET) of the pancreas. In recent years, there has been a trend towards an increase in the incidence of NET especially insulinoma.

AIM

Summarizing and analyzing current data on various approaches to the treatment of insulinoma. Our review includes a comprehensive assessment of the advantages and disadvantages of currently available insulinoma treatment methods in comparison with past experience, as well as a review of promising methods that are not currently widely used.

MATERIALS AND METHODS

Analysis of literature from such databases as scientific electronic library elibrary.ru, Pubmed, Google Scholar, MedLine, Scopus and Web of Science.

RESULTS

The most common treatment for insulinoma is surgery. For patients with high operative risk, alternative methods such as alcohol ablation, radiofrequency ablation, and tumor embolization may be used. Medications include the use of somatostatin analogues, diazoxide. The literature describes the potential benefit of the use of beta-blockers, phenytoin, glucagon, however, in clinical trials, these drugs have not demonstrated a significant effect. For the treatment of malignant and metastatically advanced insulinoma, targeted therapy (primarily Everolimus), chemotherapy, as well as embolization (including chemoembolization, radioembolization), radiofrequency ablation (RFA), microwave ablation and cryoablation, ultrasound ablation (HIFU), laser ablation, brachytherapy, irreversible electroporation are used.

CONCLUSION

The study of new drugs is an important task for scientists, among medications the most promising are new generations of somatostatin analogues, targeted drugs and chemotherapy drugs. The rare frequency of insulinoma makes it difficult to conduct randomized controlled trials and prospective studies. That is why physicians and scientists need to maintain close contacts with each other and take into account the experience of treating each patient with such disease, which will help develop effective treatment algorithms in the future.

Podophyllotoxin-mediated neurotoxicity via the microbiota-gut-brain axis in SD rats based on the toxicological evidence chain (TEC) concept

Podophyllotoxin (PPT) is a naturally occurring aryltetralin lignan. However, its clinical application has been limited due to its neurotoxicity, the mechanism of which remains unclear. This study aimed to investigate the potential involvement of the microbiota-gut-brain (MGB) axis in PPT-induced neurotoxicity using the toxicological evidence chain concept. Our approach included behavioral testing in rats, evaluation of colon and hippocampal pathological changes, examination of proinflammatory factors, brain-gut peptides, and an in-depth analysis of gut microbiome and metabolic profiles. Our results demonstrated that PPT exposure compromised cognitive functions, induced damage to the colon and hippocampus, and increased intestinal permeability in rats. Furthermore, it elevated proinflammatory factors, particularly TNF-α and IL-6, while causing disruptions in the gut microbiota, favoring Escherichia-Shigella over Lactobacillus. Significant alterations in metabolic profiles in feces, serum, and hippocampus, particularly in tryptophan metabolism with a correlation to inflammatory factors and Escherichia-Shigella, were also observed. Our findings suggest that PPT promotes the enrichment of Escherichia-Shigella leading to inflammatory factor production and alterations in kynurenine metabolism in the hippocampus, potentially contributing to neurotoxicity. The study provides novel insights into the mechanistic pathways of PPT-induced neurotoxicity, emphasizing the role of the MGB axis and offering avenues for therapeutic interventions.

[Radiotheranostics Based on Chemical Control of Radioactivity Pharmacokinetics]

Recently, radiotheranostics, which systematically combines diagnosis by nuclear medicine imaging and treatment by internal radiotherapy, constitutes a new modality in cancer treatment, with some clinical reports showing marked effects on cancer. We have been developing multifunctional chelates containing a target recognition unit, a radiation release unit, and a radioactivity pharmacokinetics control unit in the same molecule to develop efficient agents for cancer radiotheranostics based on chemical control of radioactivity pharmacokinetics. Using these compounds, we have achieved improved cancer accumulation and reduced renal accumulation in tumor-bearing mice, and have developed novel hybrid radiotheranostic agents that can be applied to simultaneously perform target-specific molecular imaging using γ-ray emitting radionuclides and internal radiotherapy using α-particle-emitting radionuclides. For example, 111In/225Ac-labeled PSMA-DA1, which targets prostate-specific membrane antigen (PSMA) for radiotheranostics, achieved clear in vivo imaging of PSMA in tumor-bearing mice and showed marked tumor growth inhibition. In addition to PSMA, this platform for radiotheranostics has also shown efficacy against various cancer target molecules, including carbonic anhydrase IX (CA-IX), which is highly expressed in hypoxic regions of cancer, and glucagon-like peptide-1 receptor (GLP-1R), which is highly expressed in insulinomas. This review presents these recent results of our studies on radiotheranostics for cancer.

An integrative view on glucagon function and putative role in the progression of pancreatic neuroendocrine tumours (pNETs) and hepatocellular carcinomas (HCC)

Cancer metabolism research area evolved greatly, however, is still unknown the impact of systemic metabolism control and diet on cancer. It makes sense that systemic regulators of metabolism can act directly on cancer cells and activate signalling, prompting metabolic remodelling needed to sustain cancer cell survival, tumour growth and disease progression. In the present review, we describe the main glucagon functions in the control of glycaemia and of metabolic pathways overall. Furthermore, an integrative view on how glucagon and related signalling pathways can contribute for pancreatic neuroendocrine tumours (pNETs) and hepatocellular carcinomas (HCC) progression, since pancreas and liver are the major organs exposed to higher levels of glucagon, pancreas as a producer and liver as a scavenger. The main objective is to bring to discussion some glucagon-dependent mechanisms by presenting an integrative view on microenvironmental and systemic aspects in pNETs and HCC biology.

Gastric variceal bleeding as a form of presentation of a pancreatic neuroendocrine tumor

NETs (neuroendocrine tumors) constitute a heterogeneous group of epithelial-type neoplasms with a predominantly neuroendocrine differentiation. Although the most common locations are the pancreas, digestive tract, and lung, this type of neoplasm can arise in virtually any organ in the body. They are rare tumors with a wide variety of clinical presentations. Symptomatic tumors are more frequent in younger patients and present at more advanced pathological stages. We present the case of a 42-year-old male with idiopathic splenomegaly and bicytopenia (anaemia and thrombocytopenia) under study by haematology department who was admitted due to an episode of melena and hemoglobin of 4.5 mg/dl. Isolated gastric varices (IGV1) with red spots were confirmed at gastroscopy and endoscopic variceal obturation using cyanoacrylate was performed in two sessions. An endoscopic ultrasonography was performed, showing thrombosis of the splenic vein extending towards the splenoportal confluence with anechoic serpiginous structures outside and inside the gastric wall suggestive of collateral circulation with gastric varices (GV). An increase in portal caliber was observed, with no signs of liver cirrhosis. Computed tomography confirms the findings. Two months/week/days later he was readmitted with rebleeding signs after starting anticoagulant treatment, so it was decided to perform a splenectomy due to failure of the endoscopic treatment. Histology revealed infiltration of the spleen by a well-differentiated neuroendocrine tumor (NET). Gallium PET/CT and Octreotid scan showed uptake in the body and tail of the pancreas with positivity for somatostatin receptors previously undetected by other means. Finally, treatment was completed with distal pancreatectomy and splenoportal axis trombectomy with vascular esplenic resection and the patient was discharged from hospital.

Detecting Somatic Mutations for Well-Differentiated Pancreatic Neuroendocrine Tumors in Endoscopic Ultrasound-Guided Fine Needle Aspiration with Next-Generation Sequencing

BACKGROUND

Pancreatic neuroendocrine tumors (PanNETs) exhibit heterogenous behavior, whereby some small tumors are aggressive with a propensity for metastasis. Detection of somatic mutations associated with aggressive biology may help with patient stratification and surgical decision-making in patients with well-differentiated PanNETs. Using next-generation sequencing (NGS), we investigated the feasibility of detecting somatic mutations in endoscopic ultrasound-guided, fine-needle aspiration (EUS-FNA) specimens and determining the mutational concordance between the EUS-FNA specimens and the primary tumors.

METHODS

Thirty-eight patients with well-differentiated, nonfunctioning PanNETs were obtained from two tertiary referral centers. Patient demographic characteristics and tumor, clinicopathologic features were collected. Tissue from both the EUS-FNA specimen and the primary tumor was extracted from archival tissue blocks. NGS using a panel of ten genes was performed on both samples.

RESULTS

In our series, the median age was 61.1 years. Tumors were predominantly left-sided (60.5%) and unifocal (94.7%). The median tumor size was 2.2 cm. NGS detected somatic mutations in 29% of primary tumors and 36.8% of EUS-FNA specimens. In primary tumors, DAXX/ATRX mutations were predominantly detected (63.6%). In EUS-FNA specimens, MEN1 mutations were predominantly detected (64.3%). Among non-wild-type specimens, mutational concordance was achieved in 31.6% of cases. In 11 patients with a detectable mutation in the primary tumor, a mutation was detected in the EUS-FNA specimen in 45.5% of cases, with a mutational concordance of 54.5%.

CONCLUSIONS

NGS can detect somatic mutations in EUS-FNA specimens of well-differentiated PanNETs. Efforts to improve detection sensitivity and mutational concordance are required to overcome current technical limitations.

Pancreatic Vasoactive Intestinal Peptide-Producing Tumor as a Rare Cause of Acute Diarrhea and Severe Hypokalemia

Pancreatic vasoactive intestinal peptide-producing tumor (VIPoma) is a rare functional neuroendocrine tumor most commonly presenting with watery diarrhea and electrolyte abnormalities that include hypokalemia, hypercalcemia and metabolic acidosis. This type of tumor has usually insidious clinical behavior that is characterized by chronic secretory diarrhea, lasting usually from months to years before diagnosis, not responsive to usual medical or dietary treatment approaches. Given the resemblance of VIPoma with other more common causes of chronic watery diarrhea, the final diagnosis is often delayed and the tumors are usually large and metastatic at the time of detection. Our case of pancreatic VIPoma demonstrates an unusual clinical course for this type of tumor with acute refractory diarrhea and rapid deterioration of patient's clinical and biochemical status that required emergent in-hospital diagnosis and treatment. Our patient is a 45-year-old woman who presented with abrupt, watery diarrhea during the past 24 h before admission accompanied with severe hypokalemia as well as hyponatremia, hyperglycemia and hypercalcemia. Despite aggressive management with fluid administration and electrolyte replenishment, no significant improvement in patient's symptoms and electrolyte imbalance was observed. After exclusion of other causes of acute diarrhea from the medical history and the laboratory tests, the clinical suspicion of a functional neuroendocrine tumor was raised. After the establishment of final diagnosis of pancreatic VIPoma with biochemical tests and magnetic resonance imaging (MRI), somatostatin analogues were prescribed and the patient underwent distal pancreatectomy and splenectomy with no signs of lymph node and splenic metastases. Few days after the surgical resection of the tumor, the patient readmitted to our hospital with tarry stools and severe anemia. The abdominal computed tomography (CT) revealed a retroperitoneal cystic lesion. The gastrointestinal bleeding gradually recessed after endoscopic hemostasis of duodenal ulcer lesions whereas the cystic lesion (postoperative lymphocele) was successfully drained under CT-guidance before discharge. After almost 10 years postoperatively, the patient is still asymptomatic with no signs of relapse or metastasis of the disease in the periodic laboratory and imaging follow-up. In conclusion, pancreatic VIPoma can sometimes manifest symptoms of abrupt onset and rapid progression that require high clinical suspicion, appropriate diagnostic workup and aggressive management.

Practical therapeutic approach in the management of diabetes mellitus secondary to Cushing's syndrome, acromegaly and neuroendocrine tumours

Cushing's syndrome, acromegaly and neuroendocrine disorders are characterized by an excess of counterregulatory hormones, able to induce insulin resistance and glucose metabolism disorders at variable degrees and requiring immediate treatment, until patients are ready to undergo surgery. This review focuses on the management of diabetes mellitus in endocrine disorders related to an excess of counterregulatory hormones. Currently, the landscape of approved agents for treatment of diabetes is dynamic and is mainly patient-centred and not glycaemia-centred. In addition, personalized medicine is more and more required to provide a precise approach to the patient's disease. For this reason, we aimed to define a practical therapeutic algorithm for management of diabetes mellitus in patients with glucagonoma, pheochromocytoma, Cushing's syndrome and acromegaly, based on our practical experience and on the physiopathology of the specific endocrine disease taken into account. This document is addressed to all specialists who approach patients with diabetes mellitus secondary to endocrine disorders characterized by an excess of counterregulatory hormones, in order to take better care of these patients. Care and control of diabetes mellitus should be one of the primary goals in patients with an excess of counterregulatory hormones requiring immediate and aggressive treatment.

Relation between WHO Classification and Location- and Functionality-Based Classifications of Neuroendocrine Neoplasms of the Digestive Tract

Practice of neuroendocrine neoplasms (NENs) of the digestive tract, which comprise of a highly diverse group of tumors with a rising incidence, faces multiple biological, diagnostic, and therapeutic issues. Part of these issues is due to misuse and misinterpretation of the classification and terminology of NENs of the digestive tract, which make it increasingly challenging to evaluate and compare the literature. For instance, grade 3 neuroendocrine tumors (NETs) are frequently referred to as neuroendocrine carcinomas (NECs) and vice versa, while NECs are, by definition, high grade and therefore constitute a separate entity from NETs. Moreover, the term NET is regularly misused to describe NENs in general, and NETs are frequently referred to as benign, while they should always be considered malignancies as they do have metastatic potential. To prevent misconceptions in future NEN-related research, we reviewed the most recent terminology used to classify NENs of the digestive tract and created an overview that combines the classification of these NENs according to the World Health Organization (WHO) with location- and functionality-based classifications. This overview may help clinicians and researchers in understanding the current literature and could serve as a guide in the clinic as well as for writing future studies on NENs of the digestive tract. In this way, we aim for the universal use of terminology, thereby providing an efficient foundation for future NEN-related research.

Diabetes Mellitus Secondary to Endocrine Diseases: An Update of Diagnostic and Treatment Particularities

Secondary diabetes mellitus is frequently ignored in specialized literature. In this narrative review, the main endocrinopathies accompanied by increased glycemic values are identified, as well as the mechanisms by which the excess or deficiency of certain hormones impact beta cell function or insulin resistance. The main endocrinopathies (acromegaly, Cushing's syndrome, Basedow-Graves' disease, pheochromocytoma, somatostatinoma and glucagonoma) and their characteristics are described along with the impact of hormone changes on blood sugar, body mass index and other parameters associated with diabetes. The overall information regarding the complex molecular mechanisms that cause the risk of secondary diabetes and metabolic syndrome is of crucial importance in order to prevent the development of the disease and its complications and particularly to reduce the cardiovascular risk of these patients. The purpose of this study is to highlight the particular features of endocrine pathologies accompanied by an increased risk of developing diabetes, in the context of personalized therapeutic decision making. The epidemiological, physiopathological, clinical and therapeutic approaches are presented along with the importance of screening for diabetes in endocrine diseases.

An Overview of Pancreatic Neuroendocrine Tumors and an Update on Endoscopic Techniques for Their Management

The growing importance of advanced endoscopy in the diagnosis and treatment of pancreatic neuroendocrine neoplasms (PanNETs) necessitates a comprehensive understanding of various biochemical markers, genetic testing methods, radiological techniques, and treatment approaches that encompass multiple disciplines within and beyond gastrointestinal oncology. This review aims to highlight key aspects of these topics, with a specific focus on emerging EUS-guided procedures for the management of PanNETs.

A Comprehensive Review on Neuroendocrine Neoplasms: Presentation, Pathophysiology and Management

Neuroendocrine neoplasms (NENs) are a group of heterogeneous tumors with neuroendocrine differentiation that can arise from any organ. They account for 2% of all malignancies in the United States. A significant proportion of NEN patients experience endocrine imbalances consequent to increased amine or peptide hormone secretion, impacting their quality of life and prognosis. Over the last decade, pathologic categorization, diagnostic techniques and therapeutic choices for NENs-both well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs)-have appreciably evolved. Diagnosis of NEN mostly follows a suspicion from clinical features or incidental imaging findings. Hormonal or non-hormonal biomarkers (like serum serotonin, urine 5-HIAA, gastrin and VIP) and histology of a suspected NEN is, therefore, critical for both confirmation of the diagnosis and classification as an NET or NEC. Therapy for NENs has progressed recently based on a better molecular understanding, including the involvement of mTOR, VEGF and peptide receptor radionuclide therapy (PRRT), which add to the growing evidence supporting the possibility of treatment beyond complete resection. As the incidence of NENs is on the rise in the United States and several other countries, physicians are more likely to see these cases, and their better understanding may support earlier diagnosis and tailoring treatment to the patient. We have compiled clinically significant evidence for NENs, including relevant changes to clinical practice that have greatly updated our diagnostic and therapeutic approach for NEN patients.

Magnetic resonance elastography-derived stiffness: potential imaging biomarker for differentiation of benign and malignant pancreatic masses

OBJECTIVE

This study sought to determine the diagnostic performance of magnetic resonance elastography (MRE) for pancreatic solid masses, compared with diffusion-weighted imaging (DWI) and serum CA19-9, to establish a threshold for differentiating between pancreatic ductal adenocarcinoma (PDAC) and benign tumors in pancreas.

MATERIALS AND METHODS

Between July 2021 to January 2023, 75 adult patients confirmed with pancreatic solid tumors were enrolled in this prospective and consecutive study. All patients underwent MRE and DWI examinations that were both performed with a spin echo-EPI sequence. Stiffness maps and apparent diffusion coefficient (ADC) maps were generated, with MRE-derived mass stiffness and stiffness ratio (computing as the ratio of mass stiffness to the parenchyma stiffness) and DWI-derived ADC values obtained by placing regions of interest over the focal tumors on stiffness and ADC maps. Further analysis of comparing diagnostic performances was assessed by calculating the area under ROC curves.

RESULTS

PDAC had significantly higher tumor stiffness [3.795 (2.879-4.438) kPa vs. 2.359 (2.01-3.507) kPa, P = 0.0003], stiffness ratio [1.939 (1.562-2.511) vs. 1.187 (1.031-1.453), P < 0.0001] and serum CA19-9 level [276 (31.73-1055) vs. 10.45 (7.825-14.15), P < 0.0001] than other pancreatic masses. Mass stiffness, stiffness ratio and serum CA19-9 showed good diagnostic performance for differentiation with AUC of 0.7895, 0.8392 and 0.9136 respectively. The sensitivity/specificity/positive predictive value/negative predictive value for differentiating malignant from benign pancreatic tumors with mass stiffness (cutoff, > 2.8211 kPa) and stiffness ratio (cutoff, > 1.5117) were 78.4/66.7/82.9/60% and 77.8/83.3/90.3/65.2% respectively. The combined performance of Mass stiffness, stiffness ratio and serum CA19-9 got an AUC of 0.9758.

CONCLUSION

MRE holds excellent clinical potential in discriminating pancreatic ductal adenocarcinoma from other pancreatic solid masses according to their mechanical properties.

Models in Pancreatic Neuroendocrine Neoplasms: Current Perspectives and Future Directions

Pancreatic neuroendocrine neoplasms (pNENs) are a heterogeneous group of tumors derived from multiple neuroendocrine origin cell subtypes. Incidence rates for pNENs have steadily risen over the last decade, and outcomes continue to vary widely due to inability to properly screen. These tumors encompass a wide range of functional and non-functional subtypes, with their rarity and slow growth making therapeutic development difficult as most clinically used therapeutics are derived from retrospective analyses. Improved molecular understanding of these cancers has increased our knowledge of the tumor biology for pNENs. Despite these advances in our understanding of pNENs, there remains a dearth of models for further investigation. In this review, we will cover the current field of pNEN models, which include established cell lines, animal models such as mice and zebrafish, and three-dimensional (3D) cell models, and compare their uses in modeling various disease aspects. While no study model is a complete representation of pNEN biology, each has advantages which allow for new scientific understanding of these rare tumors. Future efforts and advancements in technology will continue to create new options in modeling these cancers.

Biomarkers in gastroenteropancreatic neuroendocrine neoplasms

PURPOSE OF REVIEW

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) represent a heterogenous group of rare tumors emanating from neuroendocrine cells that are clinically silent for prolonged periods of time without detection. Traditional biomarkers lack sufficiently high enough specificity and sensitivity for these tumors and their secreted products. New molecules are sought to improve accuracy of detection and monitoring of GEP-NENs. The purpose of this review is to highlight recent advances in the discovery of novel biomarkers and their potential characteristics and utility as markers of GEP-NENs.

RECENT FINDINGS

Several recent GEP-NEN investigations regarding NETest demonstrate superior sensitivity and specificity in diagnosis and disease monitoring as compared with chromogranin A. Among several tissue-based emergent candidate molecules as biomarkers for GEP-NEN INSM1 has demonstrated consistently excellent characteristics when compared with traditional markers including chromogranin A, synaptophysin, and CD56.

SUMMARY

For the diagnosis and clinical monitoring of NEN, there still exists a considerable need for better biomarkers. Novel technology has resulted in a promising liquid biopsy for the detection and monitoring of GEP-NENs. The search for improved tissue biomarkers has resulted in identification of one potential candidate whereas several others remain in the investigatory phase.

Surgical Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are relatively uncommon malignancies, characterized as either functional or nonfunctional secondary to their secretion of biologically active hormones. A wide range of clinical behavior can be seen, with the primary prognostic indicator being tumor grade as defined by the Ki67 proliferation index and mitotic index. Surgery is the primary treatment modality for PNETs. While functional PNETs should undergo resection for symptom control as well as potential curative intent, nonfunctional PNETs are increasingly managed nonoperatively. There is increasing data to suggest small, nonfunctional PNETs (less than 2 cm) are appropriate follow with nonoperative active surveillance. Evidence supports surgical management of metastatic disease if possible, and occasionally even surgical management of the primary tumor in the setting of widespread metastases. In this review, we highlight the evolving surgical management of local and metastatic PNETs.

Successful Lifetime/Long-Term Medical Treatment of Acid Hypersecretion in Zollinger-Ellison Syndrome (ZES): Myth or Fact? Insights from an Analysis of Results of NIH Long-Term Prospective Studies of ZES

Analysis of the efficacy/pharmacology of long-term/lifetime medical treatment of acid hypersecretion in a large cohort of ZES patients in a prospective study. This study includes the results from all 303 patients with established ZES who were prospectively followed and received acid antisecretory treatment with either H2Rs or PPIs, with antisecretory doses individually titrated by the results of regular gastric acid testing. The study includes patients treated for short-term periods (<5 yrs), patients treated long-term (>5 yrs), and patients with lifetime treatment (30%) followed for up to 48 years (mean 14 yrs). Long-term/lifelong acid antisecretory treatment with H2Rs/PPIs can be successfully carried out in all patients with both uncomplicated and complicated ZES (i.e., with MEN1/ZES, previous Billroth 2, severe GERD). This is only possible if drug doses are individually set by assessing acid secretory control to establish proven criteria, with regular reassessments and readjustments. Frequent dose changes both upward and downward are needed, as well as regulation of the dosing frequency, and there is a primary reliance on the use of PPIs. Prognostic factors predicting patients with PPI dose changes are identified, which need to be studied prospectively to develop a useful predictive algorithm that could be clinically useful for tailored long-term/lifetime therapy in these patients.

Reprint of: The Diagnostic and Prognostic Utility of Incorporating DAXX, ATRX, and Alternative Lengthening of Telomeres (ALT) to the Evaluation of Pancreatic Neuroendocrine Tumors (PanNETs)

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and an ill-defined pathobiology. Although many PanNETs are indolent and remain stable for years, a subset may behave aggressively and metastasize widely. Thus, the increasing and frequent detection of PanNETs presents a treatment dilemma. Current prognostic systems are susceptible to interpretation errors, sampling issues, and do not accurately reflect the clinical behavior of these neoplasms. Hence, additional biomarkers are needed to improve the prognostic stratification of patients diagnosed with a PanNET. Recent studies have identified alterations in death domain-associated protein 6 (DAXX) and alpha-thalassemia/mental retardation X-linked (ATRX), as well as alternative lengthening of telomeres (ALT), as promising prognostic biomarkers. This review summarizes the identification, clinical utility, and specific nuances in testing for DAXX/ATRX by immunohistochemistry and ALT by telomere-specific fluorescence in situ hybridization in PanNETs. Furthermore, a discussion on diagnostic indications for DAXX, ATRX, and ALT status is provided to include the distinction between PanNETs and pancreatic neuroendocrine carcinomas (PanNECs), and determining pancreatic origin for metastatic neuroendocrine tumors in the setting of an unknown primary.

An Insight on Functioning Pancreatic Neuroendocrine Neoplasms

Pancreatic neuroendocrine neoplasms (PanNENs) are rare neoplasms arising from islets of the Langerhans in the pancreas. They can be divided into two groups, based on peptide hormone secretion, functioning and nonfunctioning PanNENs. The first group is characterized by different secreted peptides causing specific syndromes and is further classified into subgroups: insulinoma, gastrinoma, glucagonoma, somatostatinoma, VIPoma and tumors producing serotonin and adrenocorticotrophic hormone. Conversely, the second group does not release peptides and is usually associated with a worse prognosis. Today, although the efforts to improve the therapeutic approaches, surgery remains the only curative treatment for patients with PanNENs. The development of high-throughput techniques has increased the molecular knowledge of PanNENs, thereby allowing us to understand better the molecular biology and potential therapeutic vulnerabilities of PanNENs. Although enormous advancements in therapeutic and molecular aspects of PanNENs have been achieved, there is poor knowledge about each subgroup of functioning PanNENs.Therefore, we believe that combining high-throughput platforms with new diagnostic tools will allow for the efficient characterization of the main differences among the subgroups of functioning PanNENs. In this narrative review, we summarize the current landscape regarding diagnosis, molecular profiling and treatment, and we discuss the future perspectives of functioning PanNENs.

Epidemiological trends for functional pancreatic neuroendocrine tumors: A study combining multiple imputation with age adjustment

Purpose

The purpose of this study was to examine trends in the incidence and incidence-based (IB) mortality of functional pancreatic neuroendocrine tumors(F-PNETs), and to identify factors associated with survival times.

Methods

Data were obtained from the Surveillance, Epidemiology, and End Results database from 2000 to 2017. Trends in the age-adjusted incidence of F-PNETs and IB mortality were examined using the Joinpoint Regression Program. Statistical analyses were run using chi-square tests, Kaplan-Meier curves, and the Cox proportional hazards model. Multiple imputation was used to deal with missing data.

Results

A total of 142 patients with F-PNETs met the study inclusion criteria. It was found that the incidence of F-PNETs decreased over the study period, with an annual percent change (APC) of -2. 5% (95% CI [-4. 3, -0. 5], P<0. 05). This decrease was found to be significant for women, and also when limited to cases with distant disease or rare F-PNETs, with APCs of -4. 2% (95% CI [-7. 4, -0. 9], P<0. 05), -6. 7% (95% CI [-10. 4, -2. 8], P<0. 05), and -9. 1% (95% CI [-13. 5, -4. 4], P<0. 05), respectively. The Cox regression analysis revealed that the tumor size, tumor stage, tumor type, and surgical resection were associated with F-PNETs mortality.

Conclusions

This was the first population-based epidemiological study of F-PNETs and we found a continual decrease in the incidence of F-PNETs from 2000 to 2017. The prognosis and survival times were closely related to the calendar year at diagnosis, tumor stage, and tumor size.

177Lu-DOTATATE Efficacy and Safety in Functioning Neuroendocrine Tumors: A Joint Analysis of Phase II Prospective Clinical Trials

INTRODUCTION

Neuroendocrine tumors (NETs) are rare malignancies with different prognoses. At least 25% of metastatic patients have functioning neuroendocrine tumors (F-NETs) that secrete bioactive peptides, causing specific debilitating and occasionally life-threatening symptoms such as diarrhea and flushing. Somatostatin analogs (SSAs) are usually effective but beyond them few treatment options are available. We evaluated the clinical efficacy of 177 Lu-DOTATATE in patients with progressive metastatic F-NETs and SSA-refractory syndrome.

PATIENTS AND METHODS

A non-pre-planned joint analysis was conducted in patients enrolled in phase II clinical trials on metastatic NETs. We extrapolated data from F-NET patients with ≥1 refractory sign/symptom to octreotide, and ≥1 measurable lesion. Syndrome response (SR), overall survival (OS), progression-free survival (PFS), tolerance and disease response were analyzed.

RESULTS

Sixty-eight patients were enrolled, the majority (88.1%) with a SR. According to RECIST criteria, 1 (1.5%) patient showed a CR, 21 (32.3%) had a PR and 40 (61.5%) SD. At a median follow-up of 28.9 months (range 2.2-63.2) median PFS was 33.0 months (95%CI: 27.1-48.2). Median OS (mOS) had not been reached at the time of the analysis; the 2-year OS was 87.8% (95%CI: 76.1-94.1). Syndromic responders showed better survival than non-responders, with a 2-year OS of 93.9% (95%CI: 92.2-98.0) vs. 40.0% (95%CI: 6.6-73.4), respectively. A total of 233 adverse events were recorded. Grade 1-2 hematological toxicity was the most frequent.

CONCLUSION

The 177 Lu-DOTATATE improved symptoms and disease control in patients with F-NETs. Treatment was well tolerated. The syndrome had an impact on both quality of life and OS.

MK2 Promotes the Development and Progression of Pancreatic Neuroendocrine Tumors Mediated by Macrophages and Metabolomic Factors

Cases of pancreatic neuroendocrine tumors (PNETs) are growing in number, and new treatment options are needed in order to improve patient outcomes. The mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a crucial regulator of cytokine/chemokine production. The significance of MK2 expression and signaling pathway mediated by MK2 in PNETs has not been investigated. To characterize the impact of MK2 on PNET growth, we used the RipTag2 transgenic murine model of PNETs, and we developed a primary PNET cell line for both in vitro and in vivo studies. In the transgenic murine model of PNETs, we found that MK2 inhibition improves survival of mice and prevents PNET progression. MK2 blockade abolished cytokine/chemokine production, which was related to macrophage function. A role for MK2 in the regulation of metabolic factor secretion in PNETs was identified, making this the first study to identify a potential role for the MK2 pathway in regulation of tumor metabolism. Moreover, using an in vitro approach and allograft model of PNETs, we were able to show that macrophages with MK2 depletion exhibit increased cytotoxicity against PNET cells and substantially decreased production of pro-inflammatory cytokines and chemokines, as well as metabolic factors. Taken together, our work identifies MK2 as a potent driver of immune response and metabolic effectors in PNETs, suggesting it is a potential therapeutic target for patients with PNETs.

Role of Somatostatin Receptor 2 in Nonfunctional Pancreatic Neuroendocrine Tumors: Clinicopathological Analysis of 223 Cases and Whole Exome Sequencing of a Multifocal Case

OBJECTIVES

Somatostatin receptors are commonly expressed in most pancreatic neuroendocrine tumors (pNETs), a rare type of pancreatic tumors with high heterogeneity. However, the role of somatostatin receptor 2 (SSTR2) has seldom been investigated separately in pNET. This retrospective study aims to evaluate the role of SSTR2 in the clinicopathological features and genomic background of nonfunctional and well-differentiated pNET.

METHODS

A total of 223 cases of nonfunctional well-differentiated pNET were included, and the correlation between SSTR2 status and clinicopathological outcome was evaluated. In addition, we performed whole exome sequencing in SSTR2-positive and SSTR2-negative pNETs and identified that the 2 lesions harbored different mutational landscapes.

RESULTS

Negative SSTR2 immunochemistry staining was significantly related to an earlier onset of disease, larger tumor size, advanced stage of American Joint Committee on Cancer, and tumor metastasis in lymph nodes and liver. Under pathological assessment, positive peripheral aggression, vascular invasion, and perineural invasion were markedly increased in SSTR2-negative cases. Moreover, SSTR2-negative patients exhibited significantly worse progression-free survival than SSTR2-positive patients (hazard ratio, 0.23; 95% confidence interval, 0.10-0.53; P = 0.001).

CONCLUSIONS

Somatostatin receptor 2-negative nonfunctional pNET might represent a subtype of pNET with poor outcomes and evolve from a different genomic background.

The diagnostic and prognostic utility of incorporating DAXX, ATRX, and alternative lengthening of telomeres to the evaluation of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and an ill-defined pathobiology. Although many PanNETs are indolent and remain stable for years, a subset may behave aggressively and metastasize widely. Thus, the increasing and frequent detection of PanNETs presents a treatment dilemma. Current prognostic systems are susceptible to interpretation errors, sampling issues, and do not accurately reflect the clinical behavior of these neoplasms. Hence, additional biomarkers are needed to improve the prognostic stratification of patients diagnosed with a PanNET. Recent studies have identified alterations in death domain-associated protein 6 (DAXX) and alpha-thalassemia/mental retardation X-linked (ATRX), as well as alternative lengthening of telomeres (ALT), as promising prognostic biomarkers. This review summarizes the identification, clinical utility, and specific nuances in testing for DAXX/ATRX by immunohistochemistry and ALT by telomere-specific fluorescence in situ hybridization in PanNETs. Furthermore, a discussion on diagnostic indications for DAXX, ATRX, and ALT status is provided to include the distinction between PanNETs and pancreatic neuroendocrine carcinomas (PanNECs), and determining pancreatic origin for metastatic neuroendocrine tumors in the setting of an unknown primary.

Pediatric Neuroendocrine Neoplasms: Rare Malignancies with Incredible Variability

Neuroendocrine neoplasms (NENs) encompass a variety of neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) which can arise anywhere in the body. While relatively rare in the pediatric population, the incidence of NENs has increased in the past few decades. These neoplasms can be devastating if not diagnosed and treated early, however, symptoms are variable and can be indolent for many years. There is a reported median of 10 years from the appearance of the first symptoms to time of diagnosis. Considering some of these neoplasms have a mortality rate as high as 90%, it is crucial healthcare providers are aware of NENs and remain vigilant. With better provider education and easily accessible resources for information about these neoplasms, awareness can be improved leading to earlier disease recognition and diagnosis. This manuscript aims to provide an overview of both the most common NENs as well as the rarer NENs with high lethality in the pediatric population. This review provides up to date evidence and recommendations, encompassing recent changes in classification and advances in treatment modalities, including recently completed and ongoing clinical trials.

Prognostic and Predictive Biomarkers for Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PanNETs) represent a clinically challenging disease because these tumors vary in clinical presentation, natural history, and prognosis. Novel prognostic biomarkers are needed to improve patient stratification and treatment options. Several putative prognostic and/or predictive biomarkers (eg, alternative lengthening of telomeres, alpha-thalassemia/mental retardation, X-linked (ATRX)/Death Domain Associated Protein (DAXX) loss) have been independently validated. Additionally, recent transcriptomic and epigenetic studies focusing on endocrine differentiation have identified PanNET subtypes that display similarities to either α-cells or β-cells and differ in clinical outcomes. Thus, future prospective studies that incorporate genomic and epigenetic biomarkers are warranted and have translational potential for individualized therapeutic and surveillance strategies.

Structure-Activity Relationships and Pharmacokinetics of 111In-Labeled Glucagon-like Peptide-1 Receptor-Targeting Exendin-4 Derivatives Conjugated with Albumin Binder Moieties

Insulinomas are neuroendocrine tumors that are derived from pancreatic β-cells, and they often overexpress the glucagon-like peptide-1 receptor (GLP-1R). Radiolabeled exendin-4 derivatives have been used to noninvasively detect the GLP-1R during the diagnosis and preoperative localization of insulinomas; however, their marked renal accumulation can hinder the imaging of pancreatic tail lesions. In this study, we designed and synthesized ¹¹¹In-labeled exendin-4 derivatives that possessed 4-(4-substituted phenyl)-moieties as albumin binder (ALB) moieties ([¹¹¹In]In-E4DA2-4), and studied their structure-activity relationships and pharmacokinetics (as well as those of [¹¹¹In]In-E4DA1, which we previously reported) to determine their usefulness as radioligands for GLP-1R imaging. ¹¹¹In-labeling was performed by reacting maleimide precursors with [¹¹¹In]InCl₃ in 2-(N-morpholino)ethanesulfonic acid buffer, and then, the products were conjugated with exendin-4-Cys⁴⁰. A saturation binding assay using GLP-1R-expressing INS-1 cells was carried out to evaluate the in vitro affinity of the radioligands for the cells. In addition, the affinity of the ¹¹¹In-labeled derivatives for human serum albumin (HSA) was evaluated in an HSA-binding assay. Furthermore, an in vivo biodistribution study and single-photon emission computed tomography (SPECT) imaging were performed using INS-1 tumor-bearing mice. [¹¹¹In]In-E4DA1-4 were prepared at radiochemical yields of 6-17%. In the saturation binding assay, [¹¹¹In]In-E4DA1-4 showed a similar affinity for the INS-1 cells, indicating that the kind of ALB moiety used had no effect on the affinity of the exendin-4 derivatives for the cells. In the HSA-binding assay, [¹¹¹In]In-E4DA1-4 all bound to HSA. In the biodistribution assay, [¹¹¹In]In-E4DA1-4 exhibited marked tumor accumulation and retention. In addition, they showed lower renal accumulation than previously reported exendin-4-based radioligands without ALB moieties. The pharmacokinetics of the ¹¹¹In-labeled exendin-4 derivatives varied markedly according to the kind of ALB moiety used. In particular, [¹¹¹In]In-E4DA2, which contained a 4-(4-bromophenyl)butyric acid derivative as an ALB moiety, showed the highest tumor accumulation. SPECT imaging with [¹¹¹In]In-E4DA2 clearly visualized INS-1 tumors with no marked accumulation in normal organs. These results provide important information that will aid the design of novel exendin-4-based radioligands targeting the GLP-1R.

MRI Feature-Based Nomogram Model for Discrimination Between Non-Hypervascular Pancreatic Neuroendocrine Tumors and Pancreatic Ductal Adenocarcinomas

This study aimed to investigate whether magnetic resonance imaging (MRI) features could differentiate non-hypervascular pancreatic neuroendocrine tumors (PNETs) from pancreatic ductal adenocarcinomas (PDACs). In this study, 131 patients with surgically and pathologically proven non-hypervascular PNETs (n = 44) or PDACs (n = 87) were enrolled. Two radiologists independently analyzed MRI imaging findings and clinical features. Relevant features in differentiating non-hypervascular PNETs from PDACs were identified via univariate and multivariate logistic regression models. The MRI feature-based nomogram was constructed based on multivariable logistic analysis and the reliability of the constructed nomogram was further validated. The results showed that tumor margin (P = 0.012; OR: 6.622; 95% CI: 1.510, 29.028), MPD dilation (P = 0.047; OR: 4.309; 95% CI: 1.019, 18.227), and signal in the portal phase (P &lt; 0.001; OR: 53.486; 95% CI: 10.690, 267.618) were independent discriminative MRI features between non-hypervascular PNETs and PDACs. The discriminative performance of the developed nomogram was optimized compared with single imaging features. The calibration curve, C-index, and DCA validated the superior practicality and usefulness of the MRI-based nomogram. In conclusion, the radiologically discriminative model integrating various MRI features could be preoperatively and easily utilized to differentiate non-hypervascular PNETs from PDACs.

Preoperative treatment of benign insulinoma: diazoxide or somatostatin analogues?

Surgery is the ideal treatment of insulinoma. However, systemic therapy may be required to prevent severe preoperative hypoglycaemia, when surgery is contraindicated, delayed or refused and in case of unresectable metastatic disease. Diazoxide is commonly used but is not always effective and can cause serious side effects. Somatostatin analogues (octreotide and lanreotide) may be an alternative option. We report the case of a 27-year-old patient with insulinoma in whom diazoxide was compared with lanreotide before operation. A diagnosis of insulinoma was made on the basis of a fasting test and a 2 cm tumour confirmed in the body of the pancreas, with a high uptake of 111-In-pentreotide. Diazoxide was initiated and increased to a maximal tolerated dose of 450 mg/day. Because of dyspnoea and persisting hypoglycaemia, diazoxide was shifted to lanreotide 120 mg. All symptoms resolved without hypoglycaemia. According to the EORTC quality score of life, the score without treatment, under diazoxide, under lanreotide and after surgery were respectively 84.7, 73.3, 90.9 and 99.1. Thus, providing a positive Octreoscan, somatostatin analogues may be a safe, effective and well-tolerated option in patients with insulinoma refractory and/or intolerant to diazoxide or with a high risk of fluid retention.

Predictive Factors for Resistant Disease with Medical/Radiologic/Liver-Directed Anti-Tumor Treatments in Patients with Advanced Pancreatic Neuroendocrine Neoplasms: Recent Advances and Controversies

Simple Summary

Tumor resistance, both primary and acquired, is leading to increased complexity in the nonsurgical treatment of patients with advanced panNENs, which would be greatly helped by reliable prognostic/predictive factors. The importance in identifying resistance is being contributed to by the increased array of possible treatments available for treating resistant advanced disease; the variable clinical course as well as response to any given treatment approach of patients within one staging or grading system, the advances in imaging which are providing increasing promising results/parameters that correlate with grading/outcome/resistance, the increased understanding of the molecular pathogenesis providing promising prognostic markers, all of which can contribute to selecting the best treatment to overcome resistance disease. Several factors have been identified that have prognostic/predictive value for identifying development resistant disease and affecting overall survival (OS)/PFS with various nonsurgical treatments of patients with advanced panNENs. Prognostic factors identified for patients with advanced panNENs for both OS/PFSs include various clinically-related factors (clinical, laboratory/biological markers, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors. Particularly important prognostic factors for the different treatment modalities studies are the recent grading systems. Most prognostic factors for each treatment modality for OS/PFS are not specific for a given treatment option. These advances have generated several controversies and new unanswered questions, particularly those related to their possible role in predicting the possible sequence of different anti-tumor treatments in patients with different presentations. Each of these areas is reviewed in this paper.

Abstract

Purpose: Recent advances in the diagnosis, management and nonsurgical treatment of patients with advanced pancreatic neuroendocrine neoplasms (panNENs) have led to an emerging need for sensitive and useful prognostic factors for predicting responses/survival. Areas covered: The predictive value of a number of reported prognostic factors including clinically-related factors (clinical/laboratory/imaging/treatment-related factors), pathological factors (histological/classification/grading), and molecular factors, on therapeutic outcomes of anti-tumor medical therapies with molecular targeting agents (everolimus/sunitinib/somatostatin analogues), chemotherapy, radiological therapy with peptide receptor radionuclide therapy, or liver-directed therapies (embolization/chemoembolization/radio-embolization (SIRTs)) are reviewed. Recent findings in each of these areas, as well as remaining controversies and uncertainties, are discussed in detail, particularly from the viewpoint of treatment sequencing. Conclusions: The recent increase in the number of available therapeutic agents for the nonsurgical treatment of patients with advanced panNENs have raised the importance of prognostic factors predictive for therapeutic outcomes of each treatment option. The establishment of sensitive and useful prognostic markers will have a significant impact on optimal treatment selection, as well as in tailoring the therapeutic sequence, and for maximizing the survival benefit of each individual patient. In the paper, the progress in this area, as well as the controversies/uncertainties, are reviewed.

Development of an 111In-Labeled Glucagon-Like Peptide-1 Receptor-Targeting Exendin-4 Derivative that Exhibits Reduced Renal Uptake

Insulinomas are neuroendocrine tumors that are mainly found in the pancreas. Surgical resection is currently the first-line treatment for insulinomas; thus, it is vital to preoperatively determine their locations. The marked expression of the glucagon-like peptide-1 receptor (GLP-1R) is seen in pancreatic β-cells and almost all insulinomas. Radiolabeled derivatives of exendin-4, a GLP-1R agonist, have been used with nuclear medicine imaging techniques for the in vivo detection of the GLP-1R; however, their marked renal accumulation can hinder the imaging of pancreatic tail lesions. To develop a GLP-1R imaging probe that exhibits reduced renal accumulation, we designed and synthesized a straight-chain GLP-1R-targeting radioligand, [¹¹¹In]In-E4DA1, which consisted of exendin-4, DOTADG (a chelator), and an (iodophenyl)butyric acid derivative (an albumin binder [ALB]). We performed preclinical evaluations of [¹¹¹In]In-E4DA1 to investigate its utility as a GLP-1R imaging probe. [¹¹¹In]In-E4DA1 and [¹¹¹In]In-E4D (a control compound lacking the ALB moiety) were prepared by reacting the corresponding precursors with [¹¹¹In]InCl₃ in buffer. Cell-binding and human serum albumin (HSA)-binding assays were performed to assess the in vitro affinity of the molecules for INS-1 (GLP-1R-positive) cells and albumin, respectively. A biodistribution assay and single-photon emission computed tomography imaging were carried out using INS-1 tumor-bearing mice. In the cell-binding assay, [¹¹¹In]In-E4DA1 and [¹¹¹In]In-E4D exhibited in vitro binding to INS-1 cells. In the HSA-binding assay, [¹¹¹In]In-E4DA1 bound to HSA, while [¹¹¹In]In-E4D showed little HSA binding. The in vivo experiments involving INS-1 tumor-bearing mice revealed that the introduction of an ALB moiety into the DOTADG-based exendin-4 derivative markedly increased the molecule's tumor accumulation while decreasing its renal accumulation. In addition, [¹¹¹In]In-E4DA1 exhibited greater tumor accumulation than renal accumulation, whereas previously reported radiolabeled exendin-4 derivatives demonstrated much higher accumulation in the kidneys than in tumors. These results indicate that [¹¹¹In]In-E4DA1 may be a useful GLP-1R imaging probe, as it demonstrates only slight renal accumulation.

How Many Times Can One Go Back to the Drawing Board before the Accurate Diagnosis and Surgical Treatment of Glucagonoma?

Glucagonomas are neuroendocrine tumors (NETs) that arise from the alpha cells of the pancreatic islets. They are typically slow-growing tumors associated with abnormal glucagon secretion, resulting in one or more non-specific clinical features, such as necrolytic migratory erythema (NME), diabetes, diarrhea, deep vein thrombosis, weight loss, and depression. Here, we report the case of a 44-year-old male with a history of diabetes mellitus, presenting with a pruritic and painful disseminated cutaneous eruption of erythematous plaques, with scales and peripheral pustules, misdiagnosed as disseminated pustular psoriasis and treated for 2 years with oral retinoid and glucocorticoids. During this period, the patient complained of weight loss of 32 kg and diarrhea and developed deep vein thrombosis. These symptoms, together with an inadequate response to therapy of the skin lesions, led to the reassessment of the initial diagnosis. Laboratory tests confirmed elevated plasma glucagon levels (>1000 pg/mL) and computed tomography (CT) scans revealed a 35/44 mm tumor in the pancreatic tail. Due to considerable disease complications and the COVID-19 pandemic, the surgical removal of the tumor was delayed for nearly 2 years. During this time, somatostatin analogue therapy efficiently controlled the glucagonoma syndrome and likely prevented tumor progression. As in other functional pancreatic NETs, the early clinical recognition of hormonal hypersecretion syndrome and the multidisciplinary approach are the keys for best patient management.

Recent Advances in the Diagnosis and Management of Carcinoid Syndrome

Carcinoid syndrome, a paraneoplastic condition linked with the release of multiple humoral factors, affects around 30-40% of patients with well-differentiated neuroendocrine tumours. Carcinoid syndrome has a major and unfavourable impact on patients' quality of life; it raises costs when compared to non-functioning neuroendocrine tumours; and it causes patients' lifestyles to alter, such as food, job, physical activity, and social life. Somatostatin analogues have been the first-line therapy for individuals with neuroendocrine tumours and carcinoid disease for decades. While these drugs give considerable relief from carcinoid syndrome symptoms, clinical progression is unavoidable, necessitating further research into newer treatment measures. Carcinoid tumours are sometimes difficult to diagnose because of their vague or nonspecific symptoms. There have been several advancements in all aspects of carcinoid syndrome, as well as novel therapeutics, in the previous few years. New epidemiological studies show that it is becoming more common; increasing insights into the pathogenesis of its various clinical manifestations and its natural history: definition of prognostic factors; new methods to verify its presence; the development of new drugs to treat its various manifestations, both initially and in somatostatin-refractory cases; and an increased understanding of the pathogenesis, natural history, and management of the disease. An all language literature search was conducted on MEDLINE, COCHRANE, EMBASE, and Google Scholar till November 2021. The following search strings and Medical Subject Headings (MeSH) terms were used: "Recent advances", "Carcinoid syndrome", "Neuroendocrine Neoplasms" and "Carcinoid heart disease". We comprehensively reviewed the literature on the pathogenesis, clinical features, and newer treatment modalities for Carcinoid Syndrome. Recent advancements in research and management have resulted from advances in our understanding of the aetiology of carcinoid syndrome. The development of molecular indicators of aggressiveness improved serum tumour markers, and the molecular aetiology of carcinoid heart disease are all possible because of advances in molecular biology. We conducted a comprehensive review to update knowledge regarding the pathophysiology, diagnostic protocols, and current and newer treatments for carcinoid syndrome, which presently requires a multidisciplinary approach, due to the complexity of the illness's aetiology, diagnosis, and therapy.

Mesenteric Variceal Haemorrhage and Ectopic Cushing's Syndrome as Presenting Features of a Pancreatic Neuroendocrine Tumour Recurrence

Pancreatic neuroendocrine tumours can have varied and complex presentations. Whilst hormone hypersecretion often induces characteristic clinical syndromes, non-specific symptoms may arise due to localized tumour effects. Malignant invasion of local vasculature is an increasingly recognized complication of these neoplasms and can be associated with significant morbidity. Herein, we present the case of a 47-year-old male with a recurrence of a pancreatic neuroendocrine tumour who presented with unusual upper gastrointestinal bleeding. The tumour had recurred within the superior mesenteric vein, replacing the vessel and invading its branches. This resulted in porto-mesenteric hypertension and the formation of bleeding mesenteric varices. The patient subsequently developed progressive metabolic disturbances and was diagnosed with ectopic Cushing's syndrome, despite his primary tumour having been non-functional. This case demonstrates not only a rare pattern of tumour recurrence but also the potential for pancreatic neuroendocrine tumours to de-differentiate and change from non-functional to hormone secreting, a phenomenon which may complicate diagnosis and management.

What Are the Place and Modalities of Surgical Management for Pancreatic Neuroendocrine Neoplasms? A Narrative Review

Pancreatic neuroendocrine neoplasms (panNENs) are a heterogeneous group of tumors derived from cells with neuroendocrine differentiation. They are considered malignant by default. However, their outcomes are variable depending on their presentation in the onset of hereditary syndromes, hormonal secretion, grading, and extension. Therefore, although surgical treatment has long been suggested as the only treatment of pancreatic neuroendocrine neoplasms, its modalities are an evolving landscape. For selected patients (small, localized, non-functional panNENs), a "wait and see" strategy is suggested, as it is in the setting of multiple neuroendocrine neoplasia type 1, but the accurate size cut-off remains to be established. Parenchyma-sparring pancreatectomy, aiming to limit pancreatic insufficiency, are also emerging procedures, which place beyond the treatment of insulinomas and small non-functional panNENs (in association with lymph node picking) remains to be clarified. Furthermore, giving the fact that the liver is generally the only metastatic site, surgery keeps a place of choice alongside medical therapies in the treatment of metastatic disease, but its modalities and extensions are still a matter of debate. This narrative review aims to describe the current recommended surgical management for pancreatic NENs and controversies in light of the actual recommendations and recent literature.

Survival of Patients With Gastroenteropancreatic Neuroendocrine Tumors and Diabetes Mellitus

OBJECTIVES

Diabetes mellitus (DM) is associated with an increased risk of gastroenteropancreatic neuroendocrine tumors (GEP-NETs), but the association between DM and GEP-NET survival is unknown. We evaluated disease characteristics and survival in individuals with DM and GEP-NETs.

METHODS

Using the Surveillance, Epidemiology, and End Results registry linked to Medicare (SEER-Medicare) claims database, we examined sociodemographics, GEP-NET characteristics, and treatment in patients with and without DM before GEP-NET diagnosis. We compared survival using univariate and multivariate analyses.

RESULTS

We identified 1858 individuals with GEP-NETs: 478 (25.7%) with DM and 1380 (74.3%) without. Significant differences in race (P = 0.002) were found between the DM and non-DM groups. Compared with individuals without DM, those with DM had more gastric (9.7% vs 14.9%), duodenal (6.5% vs 10.0%), and pancreatic (17.0% vs 21.8%), and less jejunal/ileal (18.1% vs 12.8%) NETs (P < 0.0001). Patients with DM had earlier stages (stage I, 37.0%; stage IV, 30.8%) than those without (stage I, 30.6%; stage IV, 36.4%; P = 0.0012). We found no difference in survival (multivariate hazard ratio, 0.97; 95% confidence interval, 0.76-1.23) between groups.

CONCLUSIONS

Among patients with and without DM before GEP-NET diagnosis, we found differences in tumor location and stage, but not survival.

Malignant insulinoma hypoglycaemia: complex palliative management

This case presentation describes a 65-year-old woman with metastatic malignant insulinoma who experienced frequent episodes of hypoglycaemia causing significant distress and burden to her quality of life. The report describes how medical management was altered and how the patient was supported in order to alleviate these burdens. In particular, the report highlights the first documented use of flash glucose monitoring in insulinoma, which was beneficial in reducing the discomfort of lancet use and anxiety associated with hypoglycaemic episodes. This case demonstrates the benefits of an individualised approach, collaboration with other specialisms and recommends further evaluation of the use of flash glucose monitoring in palliative care.

Clinicopathological Data and Treatment Modalities for Pancreatic Somatostatinomas

BACKGROUND/AIM

Somatostatinomas (SSomas) constitute a rare neuroendocrine tumor. The purpose of this study was to evaluate the current published literature about pancreatic SSomas and report epidemiologic and clinicopathologic data for this entity.

PATIENTS AND METHODS

A combined automated and manual systematic database search of the literature was performed using electronic search engines (Medline PubMed, Scopus, Ovid and Cochrane Library), until February 2020. Statistical analysis was performed using the R language and environment for statistical computing.

RESULTS

Overall, the research revealed a total of 36 pancreatic SSoma cases. Patient mean age was 50.25 years. The most common pancreatic location was the pancreatic head (61.8%). The most frequent clinical symptom was abdominal pain (61.1%). Diagnostic algorithm most often included Computed Tomography and biopsy; surgical resection was performed in 28 cases. Out of the 36 cases, 22 had been diagnosed with a metastatic tumor and metastasectomy was performed in 6 patients with a worse overall survival (OS) (p=0.029). In total, OS was 47.74 months.

CONCLUSION

Patients with metastatic disease did not benefit from metastasectomy, but the sample size was small to reach definite conclusions. However, further studies with longer follow-up are needed for a better evaluation of these results.

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.

Digestive Well-Differentiated Grade 3 Neuroendocrine Tumors: Current Management and Future Directions

Digestive well-differentiated grade 3 neuroendocrine tumors (NET G-3) have been clearly defined since the 2017 World Health Organization classification. They are still a rare category lacking specific data and standardized management. Their distinction from other types of neuroendocrine neoplasms (NEN) not only lies in morphology but also in genotype, aggressiveness, functional imaging uptake, and treatment response. Most of the available data comes from pancreatic series, which is the most frequent tumor site for this entity. In the non-metastatic setting, surgical resection is recommended, irrespective of grade and tumor site. For metastatic NET G-3, chemotherapy is the main first-line treatment with temozolomide-based regimen showing more efficacy than platinum-based regimen, especially when Ki-67 index <55%. Targeted therapies, such as sunitinib and everolimus, have also shown some positive therapeutic efficacy in small samples of patients. Functional imaging plays a key role for detection but also treatment selection. In the second or further-line setting, peptide receptor radionuclide therapy has shown promising response rates in high-grade NEN. Finally, immunotherapy is currently investigated as a new therapeutic approach with trials still ongoing. More data will come with future work now focusing on this specific subgroup. The aim of this review is to summarize the current data on digestive NET G-3 and explore future directions for their management.

Using the Secretion Ratios of Insulin and C-peptide During the 2-h Oral Glucose Tolerance Test to Diagnose Insulinoma

BACKGROUND

Insulinoma, owing to the low incidence and small volume of the tumor, is often undiagnosed. The 72-h fast test is centered on diagnosing insulinoma; however, it cannot be performed on outpatients. Our aim was to evaluate the results of a 3-h oral glucose tolerance test (3-h OGTT) for insulinoma diagnosis.

METHODS

Thirty-seven patients with insulinoma were enrolled for comparison with 42 control subjects. All patients underwent 3-h OGTT with measurements of insulin and C-peptide. The secretion ratios of insulin and C-peptide at 1, 2, and 3 h were calculated by comparison with their values at 0 h. We used logistic regression analysis to establish the predictive models and compared the diagnostic efficiency by receiver operating characteristic analysis.

RESULTS

The fasting insulin and C-peptide levels of insulinoma patients were both higher; however, the concentrations at 1 h and 2 h were both lower (P < 0.05). The levels at 3 h were not significantly different (P > 0.05). Our final logistic regression model was constructed as follows: logit (P) = 8.305 - 0.441 × insulin 2 h/0 h ratio - 1.679 × C-peptide 1 h/0 h ratio. A cutoff value of > 0.351 showed the highest diagnostic accuracy, with an area under the curve of 0.97, a sensitivity of 86.5%, and a specificity of 95.2%.

CONCLUSIONS

The 2-h/0-h insulin ratio, as well as the 1-h/0-h C-peptide ratio, has high diagnostic efficiency for insulinoma. The 2-h OGTT can be an alternative test for diagnosing insulinoma in outpatient settings.

Multiple endocrine neoplasia type 1 (MEN-1) and neuroendocrine neoplasms (NENs)

Neuroendocrine neoplasms (NENs) are relatively rare neoplasms with 6.4-times increasing age-adjusted annual incidence during the last four decades. NENs arise from neuroendocrine cells, which release hormones in response to neuronal stimuli and they are distributed into organs and tissues. The presentation and biological behaviour of the NENs are highly heterogeneous, depending on the organ. The increased incidence is mainly due to increased awareness and improved detection methods both in the majority of sporadic NENs (non-inherited), but also the inherited groups of neoplasms appearing in at least ten genetic syndromes. The most important one is multiple endocrine neoplasia type 1 (MEN-1), caused by mutations in the tumour suppressor gene MEN1. MEN-1 has been associated with different tumour manifestations of NENs e.g. pancreas, gastrointestinal tract, lungs, thymus and pituitary. Pancreatic NENs tend to be less aggressive when arising in the setting of MEN-1 compared to sporadic pancreatic NENs. There have been very important improvements over the past years in both genotyping, genetic counselling and family screening, introduction and validation of various relevant biomarkers, as well as newer imaging modalities. Alongside this development, both medical, surgical and radionuclide treatments have also advanced and improved morbidity, quality of life and mortality in many of these patients. Despite this progress, there is still space for improving insight into the genetic and epigenetic factors in relation to the biological mechanisms determining NENs as part of MEN-1. This review gives a comprehensive update of current evidence for co-occurrence, diagnosis and treatment of MEN-1 and neuroendocrine neoplasms and highlight the important progress now finding its way to international guidelines in order to improve the global management of these patients.