The current strategy for managing pancreatic neuroendocrine tumors in multiple endocrine neoplasia type 1

Indications for genetic study in gastro-entero-pancreatic and thoracic neuroendocrine tumors

Gastro-entero-pancreatic (GEP-NET) and thoracic neuroendocrine tumours (NETs) are one of the most heritable groups of neoplasms in the body, being multiple endocrine neoplasia syndrome type 1 (MEN1), the genetic syndrome most frequently associated with this type of tumours. Moreover, Von Hippel Lindau syndrome, tuberous sclerosis, type 4 multiple neoplasia syndrome, and type 1 neurofibromatosis are associated with an increased risk of developing GEP-NETs. Another important aspect in GEP-NETs and thoracic NETs is the knowledge of the molecular background since the molecular profile of these tumours may have implications in the prognosis and in the response to specific treatments. This review summarizes the main indications for performing a genetic study in patients with GEP-NETs and thoracic NETs, and the methods used to carry it out. Moreover, it offers a description of the main hereditary syndromes associated with these NETs and their molecular background, as well as the clinical implications of the molecular profile.

Pancreatic Neuroendocrine Neoplasms: Updates on Genomic Changes in Inherited Tumour Syndromes and Sporadic Tumours Based on WHO Classification

Pancreatic neuroendocrine neoplasms (PanNENs) are the neuroendocrine neoplasms with greatest rate of increase in incidence. Approximately 10% of PanNENs arise as inherited tumour syndromes which include multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 4, von Hippel-Lindau syndrome, neurofibromatosis type1, tuberous sclerosis complex 1/2, Cowden syndrome, and Glucagon cell hyperplasia and neoplasia as well as familial insulinomatosis. In sporadic PanNENs, driver mutations in MEN1, DAXX/ATRX and mTOR pathway genes are associated with development and progression in pancreatic neuroendocrine tumours. The other changes are in VEGF pathway, Notch pathway, germline mutations in MUTYH, CHEK2, BRCA2, PHLDA3 as well as other genetic alterations. On the other hand, pancreatic neuroendocrine carcinomas share similar genetic alterations with ductal adenocarcinomas, e.g., TP53, RB1 or KRAS. In addition, microRNA and changes in immune microenvironment were noted in PanNENs. Updates on these genetic knowledges contribute to the development of management strategies for patients with PanNENs.

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.

Clinicopathological features and menin expression of pancreatic neuroendocrine neoplasm associated with multiple endocrine neoplasia type 1

Background/Purpose

We examined therapeutic strategies for pancreatic neuroendocrine neoplasm (pNEN) associated with MEN1 (M‐pNEN) by investigating clinicopathological features and menin expression.

Methods

Seventy‐seven patients who underwent resection of pNEN at our department from January 2001 to December 2017 were retrospectively analyzed. Immunohistochemical analysis of menin was performed using resected specimens.

Results

Seven patients (9%) met the diagnostic criteria for MEN1. M‐pNEN had more tumors (P < .01), a higher recurrence rate (P = .028), and higher residual pancreatic recurrence (P < .01) than sporadic pNEN (S‐pNEN). There were no significant differences in tumor size, lymph node metastasis, or World Health Organization grade between the two groups. Reduced menin staining in the tumor nuclei was found in 86% of M‐pNEN; whereas only 34% of S‐pNEN showed decreased nuclear staining. The remainder (66%) showed strong nuclear staining similar to normal islet cells (P = .0071). Furthermore, four patients (57%) with MEN1 had many microadenomas with reduced nuclear menin staining. Overall survival of M‐pNEN patients was significantly better than S‐pNEN patients (P = .049).

Conclusion

M‐pNEN patients tend to develop spatially and temporally multifocal pNENs. However, M‐pNEN patient prognosis is good with repeated surgeries at recurrence. Therefore, minimal resection with strict follow‐up is recommended rather than extensive pancreatic resections for consideration of recurrence in M‐pNEN.

Long-term Follow-up of MEN1 Patients Who Do Not Have Initial Surgery for Small ≤2 cm Nonfunctioning Pancreatic Neuroendocrine Tumors, an AFCE and GTE Study: Association Francophone de Chirurgie Endocrinienne & Groupe d'Etude des Tumeurs Endocrines

Objective:

To report long-term follow-up of patients with multiple endocrine neoplasia type 1 (MEN1) and nonfunctioning pancreatic neuroendocrine tumors (NF-PET).

Background:

Pancreaticoduodenal tumors occur in almost all patients with MEN1 and are a major cause of death. The natural history and clinical outcome are poorly defined, and management is still controversial for small NF-PET.

Methods:

Clinical outcome and tumor progression were analyzed in 46 patients with MEN1 with 2 cm or smaller NF-PET who did not have surgery at the time of initial diagnosis. Survival data were analyzed using the Kaplan-Meier method.

Results:

Forty-six patients with MEN1 were followed prospectively for 10.7 ± 4.2 (mean ± standard deviation) years. One patient was lost to follow-up and 1 died from a cause unrelated to MEN1. Twenty-eight patients had stable disease and 16 showed significant progression of pancreaticoduodenal involvement, indicated by increase in size or number of tumors, development of a hypersecretion syndrome, need for surgery (7 patients), and death from metastatic NF-PET (1 patient). The mean event-free survival was 13.9 ± 1.1 years after NF-PET diagnosis. At last follow-up, none of the living patients who had undergone surgery or follow-up had evidence of metastases on imaging studies.

Conclusions:

Our study shows that conservative management for patients with MEN1 with NF-PET of 2 cm or smaller is associated with a low risk of disease-specific mortality. The decision to recommend surgery to prevent tumor spread should be balanced with operative mortality and morbidity, and patients should be informed about the risk-benefit ratio of conservative versus aggressive management when the NF-PET represents an intermediate risk.

Evaluation and Management of Neuroendocrine Tumors of the Pancreas

Pancreatic neuroendocrine tumors are a diverse group of neoplasms with a generally favorable prognosis. Although they exhibit indolent growth, metastases are seen in roughly 60% of patients. Pancreatic neuroendocrine tumors may produce a wide variety of hormones, which are associated with dramatic symptoms, but the majority are nonfunctional. The diagnosis and treatment of these tumors is a multidisciplinary effort, and management guidelines continue to evolve. This review provides a concise summary of the presentation, diagnosis, surgical management, and systemic treatment of pancreatic neuroendocrine tumors.

Hyperinsulinaemic hypoglycaemia in children and adults

Pancreatic β cells are functionally programmed to release insulin in response to changes in plasma glucose concentration. Insulin secretion is precisely regulated so that, under normal physiological conditions, fasting plasma glucose concentrations are kept within a narrow range of 3·5-5·5 mmol/L. In hyperinsulinaemic hypoglycaemia, insulin secretion becomes dysregulated (ie, uncoupled from glucose metabolism) so that insulin secretion persists in the presence of low plasma glucose concentrations. Hyperinsulinaemic hypoglycaemia is the most common cause of severe and persistent hypoglycaemia in neonates and children. At a molecular level, mutations in nine different genes can lead to the dysregulation of insulin secretion and cause this disorder. In adults, hyperinsulinaemic hypoglycaemia accounts for 0·5-5·0% of cases of hypoglycaemia and can be due either to β-cell tumours (insulinomas) or β-cell hyperplasia. Rapid diagnosis and prompt management of hyperinsulinaemic hypoglycaemia is essential to avoid hypoglycaemic brain injury, especially in the vulnerable neonatal and childhood periods. Advances in the field of hyperinsulinaemic hypoglycaemia include use of rapid molecular genetic testing for the disease, application of novel imaging techniques (6-[fluoride-18]fluoro-levodopa [¹⁸F-DOPA] PET-CT and glucagon-like peptide 1 (GLP-1) receptor imaging), and development of novel medical treatments (eg, long-acting octreotide formulations, mTOR inhibitors, and GLP-1 receptor antagonists) and surgical therapies (eg, laparoscopic surgery).

Efficacy of endoscopic ultrasonography and endoscopic ultrasonography-guided fine-needle aspiration for the diagnosis and grading of pancreatic neuroendocrine tumors

BACKGROUND AND AIM

Pancreatic neuroendocrine tumors (pNETs) are histologically categorized according to the WHO 2010 classification by their mitotic index or Ki-67 index as G1, G2, or G3. The present study examined the efficacy of endoscopic ultrasonography (EUS) and EUS-guided fine-needle aspiration (EUS-FNA) in the diagnosis and grading of pNET.

METHODS

We retrospectively reviewed 61 pNETs in 51 patients who underwent EUS between January 2007 and June 2014. All lesions were pathologically diagnosed by surgical resection or EUS-FNA. We evaluated the detection rates of EUS for pNET and sensitivity of EUS-FNA, and compared the Ki-67 index between EUS-FNA samples and surgical specimens. EUS findings were compared between G1 and G2/G3 tumors.

RESULTS

EUS showed significantly higher sensitivity (96.7%) for identifying pNET than CT (85.2%), MRI (70.2%), and ultrasonography (75.5%). The sensitivity of EUS-FNA for the diagnosis of pNET was 89.2%. The concordance rate of WHO classification between EUS-FNA and surgical specimens was 69.2% (9/13). The concordance rate was relatively high (87.5%, 5/6) in tumors <20 mm but lower (57.1%; 4/7) in tumors ≥20 mm. Regarding EUS findings, G2/G3 tumors were more likely to be large (>20 mm), heterogeneous, and have main pancreatic duct (MPD) obstruction than G1 tumors. Multivariate analysis showed large diameter and MPD obstruction were significantly associated with G2/G3 tumors.

CONCLUSIONS

EUS and EUS-FNA are highly sensitive and accurate diagnostic methods for pNET. Characteristic EUS findings such as large tumor size and MPD obstruction are suggestive of G2/G3 tumors and would be helpful for grading pNETs.

Imaging in multiple endocrine neoplasia type 1: recent studies show enhanced sensitivities but increased controversies

In multiple endocrine neoplasia type 1 (MEN1) patients, a number of recent studies compare the ability of different, new imaging modalities to existing modalities to localize the important neuroendocrine tumors (NETs) that contribute to their decreased life expectancy (pancreatic NETs [pNETs] and thymic carcinoids). These included the use of ⁶⁸Ga-DOTATOC-PET/CT, endoscopic ultrasound and MRI. The current paper analyzes these results in light of current guidelines and controversies involved in the treatment/management of MEN1 patients. Particular attention is paid to results in these studies with thymic carcinoids and nonfunctional pNETs/gastrinomas, which recent studies show are particularly important in determining long-term survival. These studies show a number of promising imaging results but also raise a number of controversies, which will need to be addressed both in their use initially and for serial studies in these patients.

Pancreatic neuroendocrine tumors: Nosography, management and treatment

Pancreatic neuroendocrine tumors (pNETs) represent about 7% of all NETs, 8.7% of gastroenteropancreatic NETs (GEP-NETs) and 1-2% of all pancreatic neoplasms. In the last two decades, the increased diagnosis of pNETs has generated great interest and the development of different classifications, grading and staging systems. Recently, several trials were performed in order to improve the knowledge of biomarkers and imaging and to provide an early diagnosis, but their role is still under debate. Nowadays, surgery represents the only curative approach for pNETs. Approximately 90% of pNETs are silent and non-functional; therefore, most patients are diagnosed in late stage and present metastatic (60%) or locally unresectable advanced disease (21%) with a poor prognosis. Not many therapeutic options are available for pNETs, with different treatments for G1-G2 and G3 tumors, because these diseases are still rare and trials are made up of few series of patients. At present, medical treatments is controversial. On these bases, we believe that a multidisciplinary team composed of surgeons, oncologists, endocrinologists, radiation oncologists, radiologists, pathologists and medicals nuclear is required. This paper presents a review of present state-of-the-art in the field of pNETs.

Resection of primary tumor site is associated with prolonged survival in metastatic nonfunctioning pancreatic neuroendocrine tumors

BACKGROUND

Nonfunctioning pancreatic neuroendocrine tumors (NFpNET) present with distant metastases in up to 50% of patients. It is unknown whether removal of the primary tumor in patients with NFpNET and metastases is beneficial.

METHODS

We used the Surveillance, Epidemiology, and End Results database to identify patients with NFpNET and distant metastases. The primary outcome measure in this study was overall survival.

RESULTS

We identified 882 patients with metastatic NFpNET who had survival data; 303 (34%) patients had operative removal of their primary tumor of which 243 (80%) were grade I or II. Median survival of patients undergoing resection of the primary site was 65 (95% confidence interval 60-86) versus 10 (8-12) months for those without resection (P < .0001). Patients diagnosed after 2003 (n = 625, 71%) were more likely to undergo an operation than those diagnosed earlier (P = .001). Multivariable analysis showed that a lesser tumor grade (P < .0001), younger age (P < .0001), diagnosis during or after 2003 (P = .0003), tumor site in the body/tail (P = .009), and operative resection of the primary tumor site (P < .0001) were associated with prolonged survival of patients with NFpNET and distant metastases.

CONCLUSION

This study suggests that resection of the site of the primary NFpNET is associated with greater survival in patients with distant metastases and could therefore be considered as a additional treatment option in this patient population.

Conservative management and parenchyma-sparing resections of pancreatic neuroendocrine tumors: Literature review

BACKGROUND

Pancreatic neuroendocrine tumors (pNETs) are uncommon entities. pNETs are often small, slow growing, clinically silent neoplasms. However, they have an almost unpredictable biological behaviour with a not negligible malignant potential. Surgery still represents the treatment of choice, but the high morbidity associated to the enucleation or the formal pancreatectomy should be considered in the decision of the proper treatment. Management of these neoplasms is still debated, and indications for a conservative observational approach and for parenchyma sparing resections are not yet standardized.

METHOD

We review the state of art on the indications for the conservative management of pNETs. Searches on MEDLINE database were performed to identify articles reporting prognostic systems, biochemical screening, observational management, medical treatment and surgical strategies for pNETs.

DISCUSSION

Currently, an accurate 'wait-and-see' policy is recommended by the European Neuroendocrine Tumor Society (ENETS) only for non-functioning pNETs (NF-pNETs) <2 cm. A biochemical screening, based on sampling of serum levels of pancreatic polypeptide (PP) and chromogranin A, can address to early conservative surgery for MEN-1 associated NF-pNETs <2 cm to prevent their malignant transformation. The subtotal (80%) distal pancreatectomy first proposed by Thompson, often with the enucleation of possible pancreatic head tumors, still represents a good compromise between oncological radicality and prevention of pancreatic endocrine/exocrine insufficiency caused by standard radical resections for the treatment of inherited syndromes associated with NF-pNETs >2 cm and symptomatic F-pNETs of any size.

CONCLUSION

More studies are needed to further clarify and predict the biologic behaviour of pNETs and increase the indications for conservative observational management and parenchyma sparing pancreas resections.

The up-to-date review of epidemiological pancreatic neuroendocrine tumors in Japan

Pancreatic neuroendocrine tumors (PNETs) were considered an extremely rare disease. However, in recent years, the number of patients with PNET has increased rapidly. According to an epidemiological survey conducted in Japan, the number of treated patients with PNETs in 2010 was approximately 1.2-times that in 2005, and the number of new incidences of non-functional PNETs in 2010 was approximately 1.7-times that in 2005. Among functional PNETs, insulinoma was most prevalent, followed by gastrinoma. To diagnose PNETs, correct histological diagnosis is most important. According to the World Health Organization 2010 classification criteria, neuroendocrine tumors (NETs) are categorized into well-differentiated NETs and poorly differentiated neuroendocrine carcinomas (NECs). NECs accounted for 7.6% of all NETs, and functional and non-functional PNETs accounted for 2.1% and 10.1%, respectively. Patients with distant metastasis accounted for 19.9%, and those with multiple endocrine neoplasia type 1 accounted for 4.3%. When treating PNETs, it is necessary to correctly evaluate the functionality and progression of tumors, the presence or absence of metastasis, and the degrees of differentiation and malignant potential of tumors. A new registration system from the Japan Neuroendocrine Tumor Society will start to be used in 2015, which will help further dissemination of Japanese epidemiological information to the world.

Epidemiological trends of pancreatic and gastrointestinal neuroendocrine tumors in Japan: a nationwide survey analysis

BACKGROUND

Although neuroendocrine tumors (NETs) are rare, the number of patients with NET is increasing. However, in Japan, there have been no epidemiological studies on NET since 2005; thus, the prevalence of NET remains unknown.

METHODS

We reported the epidemiology of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) [pancreatic neuroendocrine tumors (PNETs) and gastrointestinal neuroendocrine tumors (GI-NETs)] in Japan in 2005. Here, we conducted the second nationwide survey on patients with GEP-NETs who received treatment in 2010.

RESULTS

A total of 3,379 patients received treatment for PNETs in 2010, representing a 1.2-fold increase in the number of patients from 2005 to 2010. The prevalence was estimated to be 2.69/100,000, with an annual onset incidence of 1.27/100,000 in 2010. Non-functioning tumor (NF)-PNETs comprised 65.5% of cases followed by insulinoma (20.9%) and gastrinoma (8.2%). Interestingly, the number of patients with NF-PNETs increased ~1.8 fold since 2005. A total of 19.9% of patients exhibited distant metastasis at initial diagnosis; 4.3% had complications with multiple endocrine neoplasia type 1 (MEN-1), and only 4.0% had NF-PNETs associated with MEN-1. Meanwhile, an estimated 8,088 patients received treatment for GI-NETs, representing a ~1.8-fold increase since 2005. The prevalence was estimated to be 6.42/100,000, with an annual onset incidence of 3.51/100,000. The locations of GI-NETs varied: foregut, 26.1%; midgut, 3.6%; and hindgut, 70.3%. Distant metastasis and complications with MEN-1 were observed in 6.0 and 0.42% at initial diagnosis, respectively. The frequency of carcinoid syndrome in patients with GI-NETs was 3.2%.

CONCLUSION

We clarified the epidemiological changes in GEP-NETs from 2005 to 2010 in Japan.

Update on pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (pNETs) are relatively rare tumors comprising 1-2% of all pancreas neoplasms. In the last 10 years our understanding of this disease has increased dramatically allowing for advancements in the treatment of pNETs. Surgical excision remains the primary therapy for localized tumors and only potential for cure. New surgical techniques using laparoscopic approaches to complex pancreatic resections are a major advancement in surgical therapy and increasingly possible. With early detection being less common, most patients present with metastatic disease. Management of these patients requires multidisciplinary care combining the best of surgery, chemotherapy and other targeted therapies. In addition to surgical advances, recently, there have been significant advances in systemic therapy and targeted molecular therapy.

Standards of care intended for multiple endocrine neoplasia families

In the past, the medical expenditure for multiple endocrine neoplasia families was high and the course of their disease not predictable. In a couple of decades, the prospects changed completely. The genetic origin of the diseases is well known and prevention is possible, whereas in advanced stages target-directed treatment is coming within reach. The most important change is the responsibility for these families. Initially, this was completely the task of the attending physician, whereas at this moment patients and disease gene carriers themselves have the central responsibility with respect to these diseases. Unfortunately, for them information about the disease is insufficiently available.

Serum chromogranin A is a useful marker for Japanese patients with pancreatic neuroendocrine tumors

Although chromogranin A (CGA) is a useful marker for pancreatic neuroendocrine tumors (pNET) in the West, its usefulness in Japanese populations is unclear. To assess this, we evaluated the serum CGA levels in 189 patients with various pancreatic diseases, including proven pNET (n = 69), pancreatic cancer (PC) (n = 50), chronic pancreatitis (CP) (n = 50) and autoimmune pancreatitis (AIP) (n = 20), and 112 normal controls (controls) using an ELISA kit. The mean CGA level of patients with pNET was significantly higher than any of the other groups (407.8 ± 984.6 ng/mL [pNET] vs 91.8 ± 101.8 ng/mL [PC], 93.6 ± 57.5 ng/mL [CP], 69.9 ± 52.4 ng/mL [AIP] and 62.5 ± 48.3 ng/mL [controls]). Limiting the analysis to patients not using proton pump inhibitors (PPI), the CGA level of patients with PC or CP was not significantly different compared with the controls. Discriminant analysis revealed that the best cut-off value of CGA to distinguish patients with pNET from the controls was 78.7 ng/mL, with a sensitivity and specificity of 53.6% and 78.6%, respectively. In patients with pNET, significant factors associating with elevated CGA levels were tumor classification, tumor size, and the presence of liver metastases in univariate analysis as well as PPI use and the presence of liver metastases in multivariate analysis. We show that CGA is a useful marker for diagnosing pNET in Japanese populations and for distinguishing patients with pNET from patients with other pancreatic diseases. The increased use of CGA in Japan will likely be a helpful tool in managing these patients, as found in the West.

Impact of long-acting octreotide in patients with early-stage MEN1-related duodeno-pancreatic neuroendocrine tumours

BACKGROUND

Somatostatin analogues (SSA) represent one of the main therapeutic option in patients affected with functioning well-differentiated neuroendocrine tumours (NETs). There are no studies specifically focusing on NETs associated with Multiple Endocrine Neoplasia type 1 (MEN1).

AIM

To evaluate the efficacy of the long-acting SSA octreotide in MEN1 patients with early-stage duodeno-pancreatic NETs.

PATIENTS AND METHODS

Forty patients with MEN1 were retrospectively evaluated. Twenty patients with evidence of one or more MEN1-related duodeno-pancreatic NETs < 20 mm in size (age range 26-61 years) were treated with octreotide long-acting octreotide (LAR) as first-line therapy. Treatment duration ranged 12-75 months. At the baseline radiological evaluation, multiple duodeno-pancreatic NETs (range 1-8, size 3-18 mm) were detected.

RESULTS

An objective tumour response was observed in 10%, stable disease in 80% and progression of disease in 10% of cases. In six patients with abnormally increased CgA, gastrin and/or insulin serum concentrations, a significant clinical and hormonal response occurred in 100% of cases and was stable along the time.

CONCLUSIONS

Therapy with SSA is highly safe and effective in patients with early-stage MEN1 duodeno-pancreatic NETs, resulting in long-time suppression of tumour and hormonal activity and 10% objective response. This suggests to early start therapy with SSA in patients with MEN1-related NETs.

Management of endocrine disease: a clinical update on tumor-induced hypoglycemia

Tumor-induced hypoglycemia (TIH) is a rare clinical entity that may occur in patients with diverse kinds of tumor lineages and that may be caused by different mechanisms. These pathogenic mechanisms include the eutopic insulin secretion by a pancreatic islet β-cell tumor, and also the ectopic tumor insulin secretion by non-islet-cell tumor, such as bronchial carcinoids and gastrointestinal stromal tumors. Insulinoma is, by far, the most common tumor associated with clinical and biochemical hypoglycemia. Insulinomas are usually single, small, sporadic, and intrapancreatic benign tumors. Only 5-10% of insulinomas are malignant. Insulinoma may be associated with the multiple endocrine neoplasia type 1 in 4-6% of patients. Medical therapy with diazoxide or somatostatin analogs has been used to control hypoglycemic symptoms in patients with insulinoma, but only surgical excision by enucleation or partial pancreatectomy is curative. Other mechanisms that may, more uncommonly, account for tumor-associated hypoglycemia without excess insulin secretion are the tumor secretion of peptides capable of causing glucose consumption by different mechanisms. These are the cases of tumors producing IGF2 precursors, IGF1, somatostatin, and glucagon-like peptide 1. Tumor autoimmune hypoglycemia occurs due to the production of insulin by tumor cells or insulin receptor autoantibodies. Lastly, massive tumor burden with glucose consumption, massive tumor liver infiltration, and pituitary or adrenal glands destruction by tumor are other mechanisms for TIH in cases of large and aggressive neoplasias.

A synchronous pancreatic neuroendocrine tumor and duodenal gastrointestinal stromal tumor

We recently encountered the case of a patient with a synchronous duodenal gastrointestinal stromal tumor (GIST) and pancreatic neuroendocrine tumor (PNET). This is the first report of this specific combination of multiple primary tumors, although three cases involving both PNET and gastric GIST have previously been reported. Since the duodenal GIST developed close to the pancreatic uncus in this case, we considered the possibility of multiple PNETs in the differential diagnosis. However, a histopathological examination using endoscopic ultrasonography-guided fine-needle aspiration confirmed the diagnosis of multiple primary lesions, involving PNET and duodenal GIST.

Advancements in pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PanNETs) have increased in incidence in the USA over the last 20 years. Although PanNETs are often misconceived as being indolent tumors as they have a far more favorable prognosis over pancreatic adenocarcinoma, roughly 60-70% of patients have metastatic disease at the time of diagnosis due to presentation late in the disease process. While improvements in imaging modalities allow for early detection and better tumor localization, recent advancements in basic science, as well as surgical and medical management of PanNETs have further improved the prognosis. The mainstay of therapy for localized PanNETs is surgical intervention, which has become safer and is slowly shifting towards a more minimally invasive approach. However, the prognosis still remains relatively bleak for patients with unresectable disease. Fortunately, novel molecular targeted therapies, such as everolimus and sunitinib, have recently come into the limelight and have shown significant promise for the treatment of locally advanced and metastatic disease.