Utility of combined use of plasma levels of chromogranin A and pancreatic polypeptide in the diagnosis of gastrointestinal and pancreatic endocrine tumors

Pancreatic neuroendocrine neoplasms (pNENs): Genetic and environmental biomarkers for risk of occurrence and prognosis

Pancreatic neuroendocrine neoplasms (pNENs) are rare and heterogeneous tumors arising from neuroendocrine cells, representing approximately 10 % of all Gastro-Entero-Pancreatic neuroendocrine neoplasms. While most pNENs are sporadic, a subset is associated with genetic syndromes such as multiple endocrine neoplasia type 1 (MEN1) or von Hippel-Lindau disease (VHL). pNENs are further classified into functioning and non-functioning tumors, with distinct clinical behaviors, prognoses, and treatment approaches. This review explores genetic and environmental biomarkers that influence the risk, prognosis, and therapeutic responses in pNENs. The epidemiology of pNENs reveals an increasing incidence, primarily due to advancements in imaging techniques. Genetic factors play a pivotal role, with germline mutations in MEN1, VHL, and other genes contributing to familial pNENs. Somatic mutations, including alterations in the mTOR pathway and DNA maintenance genes such as DAXX and ATRX, are critical in sporadic pNENs. These mutations, along with epigenetic dysregulation and transcriptomic alterations, underpin the diverse clinical and molecular phenotypes of pNENs. Emerging evidence suggests that epigenetic changes, including DNA methylation profiles, can stratify pNEN subtypes and predict disease progression. Environmental and lifestyle factors, such as diabetes, smoking, and chronic pancreatitis, have been linked to an increased risk of sporadic pNENs. While the association between these factors and tumor progression is still under investigation, their potential role in influencing therapeutic outcomes warrants further study. Advances in systemic therapies, including somatostatin analogs, mTOR inhibitors, and tyrosine kinase inhibitors, have improved disease management. Biomarkers such as Ki-67, somatostatin receptor expression, and O6-methylguanine-DNA methyltransferase (MGMT) status are being evaluated for their predictive value. Novel approaches, including the use of circulating biomarkers (NETest, circulating tumor cells, and ctDNA) and polygenic risk scores, offer promising avenues for non-invasive diagnosis and monitoring. Despite these advancements, challenges remain, including the need for large, well-annotated datasets and validated biomarkers. Future research should integrate multi-omics approaches and leverage liquid biopsy technologies to refine diagnostic, prognostic, and therapeutic strategies. Interdisciplinary collaborations and global consortia are crucial for overcoming current limitations and translating research findings into clinical practice. These insights hold promise for improving prevention, early detection, and tailored treatments, ultimately enhancing patient outcomes.

A neuroendocrine biomarker revolution from monoanalyte to multianalyte biomarkers in non-functioning gastro-entero-pancreatic neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) arise from neuroendocrine cells in a wide variety of organs. One of the most affected disease sites is the gastrointestinal system, which originates the gastro-entero-pancreatic NENs (GEP-NENs), a heterogenous group of malignancies that are rapidly increasing in incidence. These tumors can be functioning, with secretory activity leading to identifiable clinical syndromes, or non-functioning, with no secretory activity but with local symptoms of tumor growth and metastasis. A limitation in biomarkers is a crucial unmet need in non-secretory NEN management, as clinical decision-making is made more difficult by obstacles in tumor classification, prognostic evaluation, assessment of treatment response and surveillance. The objective of this review is to present existing and novel biomarkers for NENs that can function as prognostic factors and monitor disease progression or regression longitudinally, with a special emphasis on innovative research into novel multianalyte biomarkers.

Biochemical Markers for Neuroendocrine Tumors: Traditional Circulating Markers and Recent Development-A Comprehensive Review

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms presenting unique challenges in diagnosis and management. Traditional markers such as chromogranin A (CgA), pancreatic polypeptide (PP), and neuron-specific enolase (NSE) have limitations in terms of specificity and sensitivity. Specific circulating markers such as serotonin and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) and various gastrointestinal hormones such as gastrin, glucagon, somatostatin, and vasoactive intestinal peptide (VIP) have a role in identifying functional NENs. Recent advances in molecular and biochemical markers, also accounting for novel genomic and proteomic markers, have significantly improved the landscape for the diagnosis and monitoring of NENs. This review discusses these developments, focusing on both traditional markers such as CgA and NSE, as well as specific hormones like gastrin, insulin, somatostatin, glucagon, and VIP. Additionally, it covers emerging genomic and proteomic markers that are shaping current research. The clinical applicability of these markers is highlighted, and their role in improving diagnostic accuracy, predicting surgical outcomes, and monitoring response to treatment is demonstrated. The review also highlights the need for further research, including validation of these markers in larger studies, development of standardized assays, and integration with imaging techniques. The evolving field of biochemical markers holds promise for improving patient outcomes in the treatment of NENs, although challenges in standardization and validation remain.

Gastroenteropancreatic neuroendocrine neoplasms: current development, challenges, and clinical perspectives

Neuroendocrine neoplasms (NENs) are highly heterogeneous and potentially malignant tumors arising from secretory cells of the neuroendocrine system. Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are the most common subtype of NENs. Historically, GEP-NENs have been regarded as infrequent and slow-growing malignancies; however, recent data have demonstrated that the worldwide prevalence and incidence of GEP-NENs have increased exponentially over the last three decades. In addition, an increasing number of studies have proven that GEP-NENs result in a limited life expectancy. These findings suggested that the natural biology of GEP-NENs is more aggressive than commonly assumed. Therefore, there is an urgent need for advanced researches focusing on the diagnosis and management of patients with GEP-NENs. In this review, we have summarized the limitations and recent advancements in our comprehension of the epidemiology, clinical presentations, pathology, molecular biology, diagnosis, and treatment of GEP-NETs to identify factors contributing to delays in diagnosis and timely treatment of these patients.

The Quest for Circulating Biomarkers in Neuroendocrine Neoplasms: a Clinical Perspective

OPINION STATEMENT

Given the considerable heterogeneity in neuroendocrine neoplasms (NENs), it appears unlikely that a sole biomarker exists capable of fully capturing all useful clinical aspects of these tumors. This is reflected in the abundant number of biomarkers presently available for the diagnosis, prognosis, and monitoring of NEN patients. Although assessment of immunohistochemical and radiological markers remains paramount and often obligatory, there has been a notable surge of interest in circulating biomarkers over the years given the numerous benefits associated with liquid biopsies. Currently, the clinic primarily relies on single-analyte assays such as the chromogranin A assay, but these are far from ideal because of limitations such as compromised sensitivity and specificity as well as a lack of standardization. Consequently, the quest for NEN biomarkers continued with the exploration of multianalyte markers, exemplified by the development of the NETest and ctDNA-based analysis. Here, an extensive panel of markers is simultaneously evaluated to identify distinct signatures that could enhance the accuracy of patient diagnosis, prognosis determination, and response to therapy prediction and monitoring. Given the promising results, the development and implementation of these multianalyte markers are expected to usher in a new era of NEN biomarkers in the clinic. In this review, we will outline both clinically implemented and more experimental circulating markers to provide an update on developments in this rapidly evolving field.

Established and novel circulating neuroendocrine tumor biomarkers for diagnostic, predictive and prognostic use

The management of neuroendocrine tumors (NETs) represents a clinical challenge due to heterogeneity of their clinical behaviour, molecular biology and response to treatment. Over the years, several circulating biomarkers have been developed for the early diagnosis and follow-up of NETs. The specific secretory products of tumors associated with a secretory syndrome (functioning tumors) may be used as diagnostic and/or prognostic biomarkers while the most common non-specific circulating biomarkers, that may be increased in both functioning and non-functioning tumors, are chromogranin A and the neuron specific enolase. However, the diagnostic accuracy as well as the prognostic and predictive value of these biomarkers are limited and novel techniques of multianalyte analysis of regulators of tumor biology have been developed. The NETest has been most extensively studied and proved to be useful in NET diagnosis, early detection of post-operative recurrence and prediction of response to treatment but further investigation establishing higher level of evidence is required for implementation in clinical practice.

An Overview of Circulating Biomarkers in Neuroendocrine Neoplasms: A Clinical Guide

Neuroendocrine neoplasms (NENs) are a heterogeneous group of diseases that are characterized by different behavior and clinical manifestations. The diagnosis and management of this group of tumors are challenging due to tumor complexity and lack of precise and widely validated biomarkers. Indeed, the current circulating mono-analyte biomarkers (such as chromogranin A) are ineffective in describing such complex tumors due to their poor sensitivity and specificity. In contrast, multi-analytical circulating biomarkers (including NETest) are emerging as more effective tools to determine the real-time profile of the disease, both in terms of accurate diagnosis and effective treatment. In this review, we will analyze the capabilities and limitations of different circulating biomarkers focusing on three relevant questions: (1) accurate and early diagnosis; (2) monitoring of disease progression and response to therapy; and (3) detection of early relapse.

Identification, Measurement, and Assessment of the Clinical Utility of Human Pancreatic Polypeptide by Liquid Chromatography-Tandem Mass Spectrometry

Human pancreatic polypeptide (HPP) is a 36 amino acid peptide hormone that plays a role in the bidirectional communication between the digestive system and the brain. HPP measurements are used to assess vagal nerve function following sham feeding and to detect gastroenteropancreatic-neuroendocrine tumors. These tests have historically been conducted by radioimmunoassays, but liquid chromatography-tandem mass spectrometry (LC-MS/MS) has several advantages such as improved specificity and elimination of radioactive molecules. Here, we present our LC-MS/MS method. Initially, samples were immunopurified and subjected to LC-high resolution accurate mass tandem mass spectrometry (HRAM-MS/MS) to identify circulating forms of the peptide in human plasma. We identified 23 forms of HPP, including several glycosylated forms. The most abundant peptides then were used for targeted LC-MS/MS measurements. LC-MS/MS performance for precision, accuracy, linearity, recovery, limit of detection, and carryover met our acceptance criteria based on CLIA regulations. Additionally, we observed the expected physiological rise in HPP in response to sham feeding. Our results indicate that HPP measurement by LC-MS/MS produces clinically equivalent results to our established immunoassay when several peptides are monitored, making it a suitable replacement. The measurement of peptide fragments, including modified species, might have additional clinical value.

Circulating Neuroendocrine Tumor Biomarkers: Past, Present and Future

Neuroendocrine tumors are a heterogeneous group of neoplasms originating from the diffuse endocrine system. Depending on primary location and hormonal status, they range in terms of clinical presentation, prognosis and treatment. Functional tumors often develop symptoms indicating an excess of hormones produced by the neoplasm (exempli gratia insulinoma, glucagonoma and VIPoma) and can be diagnosed using monoanalytes. For non-functional tumors (inactive or producing insignificant amounts of hormones), universal biomarkers have not been established. The matter remains an important unmet need in the field of neuroendocrine tumors. Substances researched over the years, such as chromogranin A and neuron-specific enolase, lack the desired sensitivity and specificity. In recent years, the potential use of Circulating Tumor Cells or multianalytes such as a circulating microRNA and NETest have been widely discussed. They offer superior diagnostic parameters in comparison to traditional biomarkers and depict disease status in a more comprehensive way. Despite a lot of promise, no international standards have yet been developed regarding their routine use and clinical application. In this literature review, we describe the analytes used over the years and cover novel biomarkers that could find a use in the future. We discuss their pros and cons while showcasing recent advances in the field of neuroendocrine tumor biomarkers.

Plasma protein biomarkers for the detection of pancreatic neuroendocrine tumors and differentiation from small intestinal neuroendocrine tumors

There is an unmet need for novel biomarkers to diagnose and monitor patients with neuroendocrine neoplasms. The EXPLAIN study explores a multi-plasma protein and supervised machine learning strategy to improve the diagnosis of pancreatic neuroendocrine tumors (PanNET) and differentiate them from small intestinal neuroendocrine tumors (SI-NET). At time of diagnosis, blood samples were collected and analyzed from 39 patients with PanNET, 135 with SI-NET (World Health Organization Grade 1-2) and 144 controls. Exclusion criteria were other malignant diseases, chronic inflammatory diseases, reduced kidney or liver function. Prosed Oncology-II (i.e., OLink) was used to measure 92 cancer related plasma proteins. Chromogranin A was analyzed separately. Median age in all groups was 65-67 years and with a similar sex distribution (females: PanNET, 51%; SI-NET, 42%; controls, 42%). Tumor grade (G1/G2): PanNET, 39/61%; SI-NET, 46/54%. Patients with liver metastases: PanNET, 78%; SI-NET, 63%. The classification model of PanNET versus controls provided a sensitivity (SEN) of 0.84, specificity (SPE) 0.98, positive predictive value (PPV) of 0.92 and negative predictive value (NPV) of 0.95, and area under the receiver operating characteristic curve (AUROC) of 0.99; the model for the discrimination of PanNET versus SI-NET providing a SEN 0.61, SPE 0.96, PPV 0.83, NPV 0.90 and AUROC 0.98. These results suggest that a multi-plasma protein strategy can significantly improve diagnostic accuracy of PanNET and SI-NET.

Pancreatic neuroendocrine carcinoma in a pregnant woman: A case report and review of the literature

BACKGROUND

Portal venous thromboembolism caused by malignant pancreatic neuroendocrine tumor metastasis, as the initial presentation of portal hypertension and upper gastrointestinal bleeding, is a rare entity. To our knowledge, there are no reports of this entity in pregnant women. We describe a case of pancreatic neuroendocrine carcinoma during pregnancy with hematemesis and hematochezia as the initial presentation and review the literature to analyze the demographic, clinical, and pathological features to provide a reference for clinical diagnosis and treatment.

CASE SUMMARY

A 40-year-old woman presented with hematemesis and hematochezia at 26-wk gestation; she had no other remarkable medical history. The physical examination revealed normal vital signs, an anemic appearance, and lower abdominal distension. Abdominal color Doppler ultrasonography showed portal vein thrombosis, splenomegaly, intrauterine pregnancy, and intrauterine fetal death. Esophagogastroduodenoscopy revealed esophageal and gastric varicose veins and portal hypertensive gastropathy. Contrast-enhanced computed tomography demonstrated multiple emboli formation in the portal and splenic veins, multiple round shadows in the liver with a slightly lower density, portal vein broadening, varicose veins in the lower esophagus and gastric fundus, splenomegaly, bilateral pleural effusion, ascites and pelvic effusion, broadening of the common bile duct, and increased uterine volume. According to the results of Positron emission tomography-computed tomography and immunohistochemical staining, the final diagnoses were that the primary lesion was a pancreatic neuroendocrine tumor and that there were secondary intrahepatic metastases and venous cancer thrombogenesis.

CONCLUSION

Upper gastrointestinal bleeding in a pregnant woman may be caused by portal hypertension due to a malignant pancreatic neuroendocrine tumor.

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.

The Chinese guidelines for the diagnosis and treatment of pancreatic neuroendocrine neoplasms (2020)

Abstract

Pancreatic neuroendocrine neoplasms (pNENs) are highly heterogeneous, and the management of pNENs patients can be intractable. To address this challenge, an expert committee was established on behalf of the Chinese Pancreatic Surgery Association, which consisted of surgical oncologists, gastroenterologists, medical oncologists, endocrinologists, radiologists, pathologists, and nuclear medicine specialists. By reviewing the important issues regarding the diagnosis and treatment of pNENs, the committee concluded evidence-based statements and recommendations in this article, in order to further improve the management of pNENs patients in China.

Pancreatic neuroendocrine tumors: Therapeutic challenges and research limitations

Pancreatic neuroendocrine tumors (PNETs) are known to be the second most common epithelial malignancy of the pancreas. PNETs can be listed among the slowest growing as well as the fastest growing human cancers. The prevalence of PNETs is deceptively low; however, its incidence has significantly increased over the past decades. According to the American Cancer Society's estimate, about 4032 (> 7% of all pancreatic malignancies) individuals will be diagnosed with PNETs in 2020. PNETs often cause severe morbidity due to excessive secretion of hormones (such as serotonin) and/or overall tumor mass. Patients can live for many years (except for those patients with poorly differentiated G3 neuroendocrine tumors); thus, the prevalence of the tumors that is the number of patients actually dealing with the disease at any given time is fairly high because the survival is much longer than pancreatic ductal adenocarcinoma. Due to significant heterogeneity, the management of PNETs is very complex and remains an unmet clinical challenge. In terms of research studies, modest improvements have been made over the past decades in the identification of potential oncogenic drivers in order to enhance the quality of life and increase survival for this growing population of patients. Unfortunately, the majority of systematic therapies approved for the management of advanced stage PNETs lack objective response or at most result in modest benefits in survival. In this review, we aim to discuss the broad challenges associated with the management and the study of PNETs.

Biomarkers for Pancreatic Neuroendocrine Neoplasms (PanNENs) Management-An Updated Review

Pancreatic neuroendocrine tumors (PanNENs) are rare sporadic cancers or develop as part of hereditary syndromes. PanNENs can be both functioning and non-functioning based on whether they produce bioactive peptides. Some PanNENs are well differentiated while others-poorly. Symptoms, thus, depend on both oncological and hormonal causes. PanNEN diagnosis and treatment benefit from and in some instances are guided by biomarker monitoring. However, plasmatic monoanalytes are only suggestive of PanNEN pathological status and their positivity is typically followed by deepen diagnostic analyses through imaging techniques. There is a strong need for new biomarkers and follow-up modalities aimed to improve the outcome of PanNEN patients. Liquid biopsy follow-up, i.e., sequential analysis on tumor biomarkers in body fluids offers a great potential, that need to be substantiated by additional studies focusing on the specific markers and the timing of the analyses. This review provides the most updated panorama on PanNEN biomarkers.

Pancreatic neuroendocrine tumors: A review of serum biomarkers, staging, and management

Pancreatic neuroendocrine tumors (pNETs) are a heterogeneous group of tumors with complicated treatment options that depend on pathological grading, clinical staging, and presence of symptoms related to hormonal secretion. With regard to diagnosis, remarkable advances have been made: Chromogranin A is recommended as a general marker for pNETs. But other new biomarker modalities, like circulating tumor cells, multiple transcript analysis, microRNA profile, and cytokines, should be clarified in future investigations before clinical application. Therefore, the currently available serum biomarkers are insufficient for diagnosis, but reasonably acceptable in evaluating the prognosis of and response to treatments during follow-up of pNETs. Surgical resection is still the only curative therapeutic option for localized pNETs. However, a debulking operation has also been proven to be effective for controlling the disease. As for drug therapy, steroids and somatostatin analogues are the first-line therapy for those with positive expression of somatostatin receptor, while everolimus and sunitinib represent important progress for the treatment of patients with advanced pNETs. Great progress has been achieved in the combination of systematic therapy with local control treatments. The optimal timing of local control intervention, planning of sequential therapies, and implementation of multidisciplinary care remain pending.

Specific and Non-Specific Biomarkers in Neuroendocrine Gastroenteropancreatic Tumors

The diagnosis of neuroendocrine tumors (NETs) is a challenging task: Symptoms are rarely specific, and clinical manifestations are often evident only when metastases are already present. However, several bioactive substances secreted by NETs can be included for diagnostic, prognostic, and predictive purposes. Expression of these substances differs between different NETs according to the tumor hormone production. Gastroenteropancreatic (GEP) NETs originate from the diffuse neuroendocrine system of the gastrointestinal tract and pancreatic islets cells: These tumors may produce many non-specific and specific substances, such as chromogranin A, insulin, gastrin, glucagon, and serotonin, which shape the clinical manifestations of the NETs. To provide an up-to-date reference concerning the different biomarkers, as well as their main limitations, we reviewed and summarized existing literature.

Neuroendocrine neoplasms: current and potential diagnostic, predictive and prognostic markers

Some biomarkers for functioning and non-functioning neuroendocrine neoplasms (NENs) are currently available. Despite their application in clinical practice, results should be interpreted cautiously. Considering the variable sensitivity and specificity of these parameters, there is an unmet need for novel biomarkers to improve diagnosis and predict patient outcome. Nowadays, several new biomarkers are being evaluated and may become future tools for the management of NENs. These biomarkers include (1) peptides and growth factors; (2) DNA and RNA markers based on genomics analysis, for example, the so-called NET test, which has been developed for analyzing gene transcripts in circulating blood; (3) circulating tumor/endothelial/progenitor cells or cell-free tumor DNA, which represent minimally invasive methods that would provide additional information for monitoring treatment response and (4) improved imaging techniques with novel radiolabeled somatostatin analogs or peptides. Below we summarize some future directions in the development of novel diagnostic and predictive/prognostic biomarkers in NENs. This review is focused on circulating and selected tissue markers.

Prognostic significance of Chromogranin A in small pancreatic neuroendocrine tumors

BACKGROUND

The incidence of nonfunctional pancreatic neuroendocrine tumors ≤2cm is rising. The biologic behavior of these tumors is variable; thus, their management remains controversial. Chromogranin A upregulation is a useful diagnostic biomarker of neuroendocrine tumors; however, the prognostic significance of Chromogranin A is unclear. The objective of this study was to determine whether Chromogranin A levels have prognostic value in pancreatic neuroendocrine tumor patients and may help guide management.

METHODS

We evaluated the National Cancer Database over a 10-year period (2004-2013). Patients with pancreatic neuroendocrine tumors measuring ≤2cm, without distant metastases, were identified and categorized as Chromogranin A high (>420ng/mL) or Chromogranin A low (≤420ng/mL), and those lacking data on Chromogranin A levels were excluded from the study. Univariate and multivariate analyses were performed using Cox proportional hazards model. Cut-point determination was performed using the Contal and O'Quigley method.

RESULTS

Of the 445 eligible patients, 352 (79%) were Chromogranin A low and 93 (21%) were Chromogranin A high. Median Chromogranin A level was 71ng/mL (interquartile range, 24-294ng/mL). Chromogranin levels were associated with clinical nodal status and grade. Furthermore, on multivariate analysis, Chromogranin A levels (Chromogranin A high versus Chromogranin A low) independently predicted overall survival after controlling for tumor size, grade, clinical nodal status, and academic status of the facility (hazard ratio: 7.90, 95%CI: 2.34-26.69, P = .001). The greatest benefit of surgical resection was noted in patients in the Chromogranin A high subgroup (log-rank P <.001).

CONCLUSION

Serum Chromogranin A levels can be incorporated in surgical decision-making for patients with small pancreatic neuroendocrine tumors. Patients in the Chromogranin A low group can be considered for observation, whereas patients in the Chromogranin A high group should be strongly considered for resection.

Role of biomarker tests for diagnosis of neuroendocrine tumours

Neuroendocrine tumours (NETs) are neoplasms that arise from neuroendocrine cells. Neuroendocrine cells and their tumours can secrete a wide range of amines and polypeptide hormones into the systemic circulation. This feature has triggered widespread investigation into circulating biomarkers for the diagnosis of NETs as well as for the prediction of the biological behaviour of tumour cells. Classic examples of circulating biomarkers for gastroenteropancreatic NETs include chromogranin A, neuron-specific enolase and pancreatic polypeptide as well as hormones that elicit clinical syndromes, such as serotonin and its metabolites, insulin, glucagon and gastrin. Biomarker metrics of general markers for diagnosing all gastroenteropancreatic NET subtypes are limited, but specific hormonal measurements can be of diagnostic value in select cases. In the past decade, methods for detecting circulating transcripts and tumour cells have been developed to improve the diagnosis of patients with NETs. Concurrently, modern scanning techniques and superior radiotracers for functional imaging have markedly expanded the options for clinicians dealing with NETs. Here, we review the latest research on biomarkers in the NET field to provide clinicians with a comprehensive overview of relevant diagnostic biomarkers that can be implemented in dedicated situations.

The Levels of Tumor Markers in Pancreatic Neuroendocrine Carcinoma and Their Values in Differentiation Between Pancreatic Neuroendocrine Carcinoma and Pancreatic Ductal Adenocarcinoma

OBJECTIVES

The levels of tumor markers in pancreatic neuroendocrine carcinoma (PNEC) are unknown, and imaging findings of PNEC and pancreatic ductal adenocarcinoma (PDAC) have overlaps. In this study, we show the tumor markers in PNEC and evaluate their values for distinguishing PNEC from PDAC.

METHODS

Thirty-three cases of PDAC and 21 cases of PNEC were retrospectively evaluated. The demographic information and clinical data were reviewed.

RESULTS

Pancreatic neuroendocrine carcinoma was usually misdiagnosed (57.1%) as PDAC based on imaging findings. Abnormal carbohydrate antigen (CA) 19-9, carcinoembryonic antigen (CEA), and α-fetoprotein (AFP) were observed in 19.0% to 28.6% of PNECs. Abnormal CA 19-9 and CA 125 levels were more common in PDAC than in PNEC (P < 0.05). Higher level of AFP was more common in PNEC than in PDAC (33.3% vs 3.0%, P < 0.05). The cutoff value of CA 19-9 for detecting PNEC was calculated as 38.5 U/mL or less with 0.788 sensitivity and 0.800 specificity. Carbohydrate antigen 19-9 (odds ratio [OR], 22.9; 95% confidence interval [CI], 2.94-179.3), AFP (OR, 0.08; 95% CI, 0.012-0.564), and CA 125 (OR, 17.4; 95% CI, 1.13-267.3) were predictors in differentiating PDAC from PNEC.

CONCLUSIONS

Carbohydrate antigen 19-9, AFP, and CA 125 have potential for distinguishing hypovascularized PNEC from PDAC.

Comparison between Two Methods in the Determination of Circulating Chromogranin A in Neuroendocrine Tumors (NETs): Results of a Prospective Multicenter Observational Study

Several methods for analyzing CgA using either monoclonal or polyclonal antibodies have been developed, which differ in their diagnostic performance. The present paper describes the results of a prospective multicenter study aimed at comparing the clinical value of the two most widely used commercially available CgA assay kits in patients affected by neuroendocrine tumors (NETs). Two hundred sixty-one patients from 40 different centers and 99 healthy subjects were evaluated. CgA levels were measured with two different methods, a two-step immunoradiometric assay (IRMA) and an enzyme-linked immunosorbent assay (ELISA). CgA was measured centrally by two reference laboratories, one of which used IRMA and the other ELISA, and it was measured by the participating institutions with the method routinely used by each of them. The major findings of the present study were: (i) the two assays for the determination of CgA present good diagnostic performance; (ii) both assays are robust and guarantee comparable results when applied in different settings (central vs local laboratory); (iii) the negative/positive cutoff points (87 ng/mL for IRMA and 21.3 U/L for ELISA) were established according to standardized criteria; (iv) the results obtained with the two assays in basal clinical samples of patients affected by NETs show an apparently satisfactory correlation (rs=0.843, p<0.0001). However, a possibly clinically meaningful 36% discordance rate was found. These findings support the hypothesis that the two CgA kits might provide partially different information.

Chromogranin A as circulating marker for diagnosis and management of neuroendocrine neoplasms: more flaws than fame

Owing to the heterogeneity of neuroendocrine neoplasms (NENs), the availability of reliable circulating markers is critical for improving diagnostics, prognostic stratification, follow-up and definition of treatment strategy. This review is focused on chromogranin A (CgA), a hydrophilic glycoprotein present in large dense core vesicles of neuroendocrine cells. Despite being long identified as the most useful NEN-related circulating marker, clinical application of CgA is controversial. CgA assays still lack standardization, thus hampering not only clinical management but also the comparison between different analyses. In the diagnostic setting, clinical utility of CgA is limited as hampered by (a) the variety of oncological and non-oncological conditions affecting marker levels, which impairs specificity; (b) the fact that 30-50% of NENs show normal CgA, which impairs sensitivity. Regarding the prognostic phase, there is prospective evidence which demonstrates that advanced NENs secreting CgA have poorer outcome, as compared with those showing non-elevated marker levels. Although the identification of cut-offs allowing a proper risk stratification of CgA-secreting patients has not been performed, this represents the most important clinical application of the marker. By contrast, based on prospective studies, the trend of elevated circulating CgA does not represent a valid indicator of morphological evolution and has therefore no utility for the follow-up phase. Ultimately, current knowledge about the role of the marker for the definition of treatment strategy is poor and is limited by the small number of available studies, their prevalent retrospective nature and the absence of control groups of untreated subjects.

Hormone secreting gastro-entero-pancreatic neuroendocrine neoplasias (GEP-NEN): When to consider, how to diagnose?

Neuroendocrine neoplasms of the digestive system (GEP-NEN) represent a heterogeneous group of malignancies with various clinical presentation and prognosis. GEP-NENs can potentially affect all organs of the gastrointestinal tract; characteristically they share the biological property to produce and secrete peptides and neuroamines. About 30% of GEP-NENs are hormonally active and can cause specific clinical syndromes. The clinical presentation mainly depends on the primary site of the tumor and its functionality. Because of the wide spectrum of clinical symptoms and their misperceived rarity, diagnosis of GEP-NENs is often delayed for years and tumors are detected first in an advanced stage. Early identification of a specific hormonal syndrome can significantly impact tumor diagnosis and treatment, moreover the preoperative management of NEN hormonal release avoids potential life threatening hormonal crisis. However, GEP-NEN diagnostic work-up is challenging, it requires a multidisciplinary team and needs particular experience; standardized protocols and clinical experience are essential for a proper endocrine diagnostic work-up. In addition to the biochemical diagnostic, further radiologic and endoscopic imaging modalities are required moreover, somatostatin-receptor based functional imaging, using either Octreotide-scintigraphy or novel PET-based techniques with specific isotopes like Ga⁶⁸-DOTA-octreotate, plays an important role for the detection of the primary tumor as well as for the evaluation of the tumor extent.

The future: diagnostic and imaging advances in MEN1 therapeutic approaches and management strategies

Prospective randomized data are lacking, but current clinical expert guidelines recommend annual screening examinations, including laboratory assessments and various imaging modalities (e.g. CT, MRI, scintigraphy and EUS) for patients with multiple endocrine neoplasia type 1 (MEN1). Routine screening is proposed to detect and localize neuroendocrine manifestations as early as possible. The goal is timely intervention to improve quality of life and to increase life expectancy by preventing the development of life-threatening hormonal syndromes and/or metastatic disease. In recent years, some studies compared different and new imaging methods regarding their sensitivity and utility in MEN1 patients. This present article reviews the proposed diagnostic tools for MEN1 screening as well as potential future perspectives.

Anticancer Effects of Baicalein in Pancreatic Neuroendocrine Tumors In Vitro and In Vivo

OBJECTIVES

Baicalein is a Chinese traditional medicine that inhibits tumor migration and growth. Pancreatic neuroendocrine tumors (pNETs) have a high incidence in China, but there are still no effective treatments. The aim of our study was to investigate whether baicalein could inhibit pNETs.

METHODS

In vitro, we used BON1-a cell line of pNETs-to analyze the apoptosis and migration and invasion after baicalein treatment via flow cytometry and Western blot. In vivo, we used a xenograft tumors model to evaluate the size of tumors after baicalein treatment. Western blot was used to analyze the expression of apoptosis and migration-related protein.

RESULTS

In vitro, the Cell Counting Kit 8 assay showed that baicalein decreased BON1 viability, and flow cytometry demonstrated that baicalein induced BON1 apoptosis and protein changes. In addition, baicalein inhibited BON1 migration and invasion as shown via a Transwell assay. In vivo, baicalein inhibited tumor growth and migration and also increased apoptosis-related protein expression.

CONCLUSIONS

Baicalein could increase caspase-3 and Bax expression and decrease survivin and Bcl-2 to induce apoptosis. It inhibits migration and invasion by decreasing expression of vascular endothelial growth factor and matrix metalloproteinases 2 and 9.

Histone deacetylase inhibitor thailandepsin-A activates Notch signaling and suppresses neuroendocrine cancer cell growth in vivo

Novel therapies for neuroendocrine (NE) cancers are desperately needed as they frequently present as metastatic disease and cause debilitating symptoms by secreting excessive hormones. Induction of Notch isoforms has a tumor suppressive effect in NE cancer cell lines, and we have observed that histone deacetylase inhibitors (HDACi) potently activate Notch. In this study, we describe the potential for Burkholderia thailandensis-derived class I HDACi thailandepsin A (TDP-A) as a Notch activator and therapeutic agent against NE cancer. IC₅₀ for TDP-A was determined to be 4-6 nM in NE cancer cell lines (BON, MZ-CRC-1, and TT) without cytotoxicity to lung fibroblasts. The binding characteristics of TDP-A to its target HDAC1 was examined using bioluminescence resonance energy transfer (BRET). Western blot and flow cytometry analysis showed that TDP-A induces cell cycle arrest and apoptosis in a dose-dependent manner. TDP-A dose-dependently activated the Notch pathway as measured by increasing functional CBF1-luciferase reporter signal and mRNA and protein expressions of Notch isoforms, which were attenuated by pretreatment with γ-secretase inhibitor DAPT. Furthermore, TDP-A lead to changes in expression level of downstream targets of Notch pathway and reduced expression of NE cancer markers. An in vivo study demonstrated that TDP-A suppressed NE cancer progression. These results show that TDP-A, as a Notch activator, is a promising agent against NE cancers.

Mesenteric Lymphadenectomy in Well-Differentiated Appendiceal Neuroendocrine Tumors

BACKGROUND

Surgical resection is the primary therapy for local and locally advanced appendiceal neuroendocrine tumors. The role of mesenteric lymphadenectomy in these patients is undefined.

OBJECTIVE

The purpose of this study was to define the role and prognostic significance of mesenteric lymphadenectomy.

DESIGN

This was a retrospective, observational study.

SETTINGS

A population-based cohort from the National Cancer Institute Surveillance, Epidemiology, and End Results registry (January 1988 to November 2013) was used.

PATIENTS

Patients with well-differentiated neuroendocrine tumors and nonmixed histologies undergoing surgical resection were included.

MAIN OUTCOME MEASURES

The risk of lymph node metastases as a function of tumor size and overall survival with respect to lymph node count and tumor size was measured. Lymph node cut-point was determined using the Contal and O'Quigely method.

RESULTS

Of the 573 patients who met the inclusion criteria, 64% were women, 79% were white, and 76% were <60 years of age. Seventy percent of the tumors were ≤2 cm, and 77% were lymph node negative. Median lymph nodes retrieved were 0 (interquartile range, 0-14). The probability of nodal metastases was 2.7% in tumors ≤1.0 cm, 31.0% in tumors 1.1 to 2.0 cm, and 64.0% in tumors >2.0 cm. The probability of a positive lymph node increased with increasing lymph node count up to 26 lymph nodes. An ideal cut-point of 12 lymph nodes was identified by statistical modeling. After adjustment in the multivariable model, the group with 12 or fewer lymph nodes examined had significantly worse overall survival (HR = 4.33 (95% CI, 1.54-12.15); p = 0.005; 5-year survival, 88% versus 96%) than the group with more than 12 lymph nodes examined.

LIMITATIONS

Analysis was limited by the variables available in the database.

CONCLUSIONS

This is the largest study to date that looks at prognostic significance of lymph node count for well-differentiated appendiceal neuroendocrine tumors. Overall survival was worse where 12 or fewer lymph nodes were identified for tumors >1 cm. See Video Abstract at http://links.lww.com/DCR/A352.

Peptidome profiling of human serum of uveal melanoma patients based on magnetic bead fractionation and mass spectrometry

AIM

To find new biomarkers for uveal melanoma (UM) by analyzing the serum peptidome profile.

METHODS

Proteomic spectra in patients with UM before and after operation were analyzed and compared with those of healthy controls. Magnetic affinity beads were used to capture serum peptides and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer were used to compile serum peptide profiles.

RESULTS

A panel of 49 peptides were differentially expressed between UM patients and controls, of which 33 peptides were of higher intensities in patient group and 16 peptides were of higher intensities in control group. Based on combined use of these potential markers, peptides with mean molecular masses of 1467 and 9289.0 Da provide high sensitivity (83.3%), specificity (100%) and accuracy rate (93.0%) together to differentiate melanoma patients from healthy controls. At the time point of 6mo postoperatively, the levels of many peptides differentially expressed before surgery showed no more statistical difference between the patients and the control group. Fibrinogen α-chain precursors were identified as potential UM markers.

CONCLUSION

We have shown that a convenient and fast proteomic technique, affinity bead separation and MALDI-TOF analysis combined with bioinformatic software, facilitates the identification of novel biomarkers for UM.

Utility of chromogranin A, pancreatic polypeptide, glucagon and gastrin in the diagnosis and follow-up of pancreatic neuroendocrine tumours in multiple endocrine neoplasia type 1 patients

OBJECTIVE

Pancreatic neuroendocrine tumours (PNETs) are the major source of disease-specific mortality in multiple endocrine neoplasia type 1 (MEN1) patients. Chromogranin A (CgA), pancreatic polypeptide (PP), glucagon and gastrin have some diagnostic value in sporadic PNETs, but there is very little evidence for their efficacy in diagnosing PNETs in MEN1 patients.

DESIGN

We performed a retrospective chart review of the existing MEN1 database in our institution.

PATIENTS

One hundred and thirteen patients were eligible for diagnostic value analysis of tumour markers. Patients were excluded if measurement of tumour markers was missing, either 3 months prior to PNET diagnosis (PNET patients) or prior to abdominal imaging (non-PNET patients).

MEASUREMENTS

Clinicopathologic characteristics and of tumour marker measurements were analysed.

RESULTS

Of 293 confirmed MEN1 cases, 55 PNETs and 58 non-PNETs met inclusion criteria. The area under the curve (AUC) for CgA, PP, glucagon and gastrin in MEN1 cases was 59·5%, 64·1%, 77·0% and 75·9%, respectively. The AUC for the combination of CgA, PP and gastrin was 59·6%. PP, but not CgA, glucagon or gastrin was significantly associated with both age and PNET functional status (P = 0·0485 and 0·0188, respectively). No markers were significantly associated with sex, PNET size, tumour number, tumour location, American Joint Committee on Cancer (AJCC) stage, presence of lymph node metastasis, lymphovascular invasion or overall survival. CgA values were not significantly lower following PNET resection than pre-operatively (P = 0·554).

CONCLUSIONS

The value of blood markers for diagnosing PNETs in MEN1 patients is relatively low, even when used in combination.

Pheochromocytoma of the pancreas: A report of three cases and a literature review

Pheochromocytoma is primarily derived from the adrenal medulla. The majority of extra-adrenal pheochromocytoma cases occur in the superior para-aortic region and para-adrenal area. However, pheochromocytoma originating from the pancreas is rare. The present study reports the cases of three patients who had no history of hypertension but were post-operatively diagnosed with pheochromocytoma located in the pancreas. Of the three patients, two were admitted to hospital due to abdominal pain, and imaging examinations revealed a soft-tissue lesion in the head of pancreas. Local resection of the pancreatic tumor was successfully performed and a diagnosis of pheochromocytoma derived from the pancreas was subsequently made by pathologists. The third patient was admitted to hospital for surgical treatment due to the identification of a continuously growing lesion in the tail of pancreas during physical examinations. Distal resection of the pancreas was stopped during surgery when the patient's blood pressure and heart rate suddenly increased to 180/110 mmHg and 140 beats/min, respectively. Due to a marked rise in noradrenaline and adrenaline levels in the blood subsequent to surgery, the patient was diagnosed with pancreatic pheochromocytoma. The present study additionally reviewed the associated literature concerning pheochromocytoma in order to improve the understanding of this rare clinical phenomenon. The aim of the present study is to highlight to surgeons that although patients may not present with typical clinical manifestations due to the non-functional status of the tumor, undiagnosed pheochromocytoma of the pancreas should be considered when surgeons observe an unexpected hypertensive crisis during pancreatic tumor surgery.

Clinical Presentation and Diagnosis of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are slow-growing neoplasms capable of storing and secreting different peptides and neuroamines. Some of these substances cause specific symptom complexes, whereas others are silent. They usually have episodic expression, and the diagnosis is often made at a late stage. Although considered rare, the incidence of NETs is increasing. For these reasons, a high index of suspicion is needed. In this article, the different clinical syndromes and the pathophysiology of each tumor as well as the new and emerging biochemical markers and imaging techniques that should be used to facilitate an early diagnosis, follow-up, and prognosis are reviewed.

Consensus on biomarkers for neuroendocrine tumour disease

Management of neuroendocrine neoplasia represents a clinical challenge because of its late presentation, lack of treatment options, and limitations in present imaging modalities and biomarkers to guide management. Monoanalyte biomarkers have poor sensitivity, specificity, and predictive ability. A National Cancer Institute summit, held in 2007, on neuroendocrine tumours noted biomarker limitations to be a crucial unmet need in the management of neuroendocrine tumours. A multinational consensus meeting of multidisciplinary experts in neuroendocrine tumours assessed the use of current biomarkers and defined the perquisites for novel biomarkers via the Delphi method. Consensus (at >75%) was achieved for 88 (82%) of 107 assessment questions. The panel concluded that circulating multianalyte biomarkers provide the highest sensitivity and specificity necessary for minimum disease detection and that this type of biomarker had sufficient information to predict treatment effectiveness and prognosis. The panel also concluded that no monoanalyte biomarker of neuroendocrine tumours has yet fulfilled these criteria and there is insufficient information to support the clinical use of miRNA or circulating tumour cells as useful prognostic markers for this disease. The panel considered that trials measuring multianalytes (eg, neuroendocrine gene transcripts) should also identify how such information can optimise the management of patients with neuroendocrine tumours.

Non-functional neuroendocrine tumors of the pancreas: Advances in diagnosis and management

Nonfunctional neuroendocrine tumors of the pancreas (NF-PNETs) are a heterogeneous group of neoplasms. Although rare, the incidence of NF-PNETs is increasing significantly. The classification of PNETs has evolved over the past decades and is now based on a proliferation grading system. While most NF-PNETs are slow growing, tumors with more aggressive biology may become incurable once they progress to unresectable metastatic disease. Tumors of higher grade can be suspected preoperatively based on the presence of calcifications, hypoenhancement on arterial phase computed tomography, positron emission technology avidity and lack of octreotide scan uptake. Surgery is the only curative treatment and is recommended for most patients for whom complete resection is possible. Liver-directed therapies (thermal ablation, transarterial embolization) can be useful in controlling unresectable hepatic metastatic disease. In the presence of unresectable progressive disease, somatostatin analogues, everolimus and sunitinib can prolong progression-free survival. This article provides a comprehensive review of NF-PNETs with special emphasis on recent advances in diagnosis and management.

A Single Centre Analysis of Clinical Characteristics and Treatment of Endocrine Pancreatic Tumours

Background. Endocrine Pancreatic Tumours (PENs) are rare and can be nonfunctioning or functioning. They carry a good prognosis overall though high grade lesions show a relatively shorter survival. The aim of the current study is to describe a single centre analysis of the clinical characteristics and surgical treatment of PENs. Patients and Methods. This is a cohort analysis of 40 patients of PENs who underwent surgery at Sir Ganga Ram Hospital, New Delhi, India, from 1995 to 2013. Patient particulars, clinical features, surgical interventions, postoperative outcome, and followup were done and reviewed. The study group was divided based on grade (G1, G2, and G3) and functionality (nonfunctioning versus functioning) for comparison. Results. PENs comprised 6.3% of all pancreatic neoplasms (40 of 634). Twenty-eight patients (70%) had nonfunctioning tumours. Eighteen PENs (45%) were carcinomas (G3), all of which were nonfunctioning. 14 (78%) of these were located in the pancreatic head and uncinate process (P = 0.09). The high grade (G3) lesions were significantly larger in size than the lower grade (G1 + G2) tumours (7.0 ± 3.5 cms versus 3.1 ± 1.6 cms, P = 0.007). Pancreatoduodenectomy was performed in 18 (45%), distal pancreatectomy in 10 (25%), and local resection in 8 (20%) and nonresective procedures were performed in 4 patients (10%). Fourteen patients (35%) had postoperative complications. All G3 grade tumours which were resected had positive lymph nodes (100%) and 10 had angioinvasion (71%). Eight neoplasms (20%) were cystic, all being grade G3 carcinomas, while the rest were solid. The overall disease related mortality attributable to PEN was 14.3% (4 of 28) and for malignant PENs was 33.3% (4 of 12) after a mean follow-up period of 49.6 months (range: 2–137 months). Conclusion. Majority of PENs are nonfunctioning. They are more likely malignant if they are nonfunctioning and large in size, show cystic appearance, and are situated in the pancreatic head. Early surgery leads to good long term survival with acceptable postoperative morbidity.

Pancreatic neuroendocrine tumors: targeting the molecular basis of disease

PURPOSE OF REVIEW

Pancreatic neuroendocrine tumors (pNETs) are a rare and heterogeneous group of neoplasia. Presentation of these tumors can vary widely. Current treatment modalities range from potentially curative surgical interventions in localized disease to the use of varied hormonal analogues, cytotoxic agents and targeted therapy for the management of locally advanced and metastatic disease. With such a wide variety of therapeutic modalities, clinicians are faced with the task of building an effective and comprehensive treatment strategy for their patients.

RECENT FINDINGS

Targeted therapy for pNET is limited to sunitinib and everolimus. There have been a number of important studies assessing the efficacy of other targeted agents, in addition to the conjugation of these agents in the management of advanced pNET. This review will stand to highlight currently available targeted therapies for the treatment of advanced pNET.

SUMMARY

The use of targeted agents in the management of advanced pNET has significant potential to change the current standard of care. In addition to the use of long-acting somatostatin analogues, targeting the mammalian target of rapamycin and vascular endothelial growth factor pathways can be well tolerated and may lead to long periods of disease control in a wide variety of neuroendocrine tumors involving the pancreas.

Diagnostic value of circulating chromogranin a for neuroendocrine tumors: a systematic review and meta-analysis

Background

In previous decades, chromogranin A (CgA) has been demonstrated to be the most promising biomarker for the diagnosis of neuroendocrine tumors (NETs), but its diagnostic value is still controversial. This meta-analysis aimed to estimate the potential diagnostic value of circulating CgA for NETs.

Methods

We collected relevant studies from several electronic databases as well as from reference lists. Diagnostic indices of CgA were pooled with random effects models. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and summary receiver operating characteristic (SROC) curves for the diagnosis of NETs were used to estimate the overall diagnostic efficiency.

Results

Through a search strategy, 13 studies met the inclusion criteria and were included. These studies contained 1260 patients with NETs and 967 healthy controls in the total sample. As a result, the overall sensitivity, specificity and diagnostic odds ratio (DOR) were 0.73 (95% CI: 0.71 to 0.76), 0.95 (95% CI: 0.93 to 0.96) and 56.29 (95% CI: 25.27 to 125.38), respectively, while the summary positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 14.56 (95% CI: 6.62 to 32.02) and 0.26 (95% CI: 0.18 to 0.38), respectively. In addition, the area under the curve (AUC) of the circulating CgA in the diagnosis of NETs was 0.8962.

Conclusions

These data demonstrate that circulating CgA is an efficient biomarker for the diagnosis of NETs with high sensitivity and specificity, which indicates that it may be helpful for the clinical management of NETs. However, further studies are needed to clarify this issue.

Circulating tumor markers in patients with neuroendocrine tumors – a clinical perspective

Abstract: 

Neuroendocrine tumors (NETs) are uncommon malignancies with a very diverse presentation and prognosis. Patients with NETs frequently have circulating tumor biomarkers that may aid in the diagnosis and help with prognostication. The most commonly used and best studied marker is chromogranin A, which appears to reflect the tumor burden and is useful at the time of diagnosis, and to monitor for recurrence after resection as well as to assess response to systemic therapy. Despite being the best studied marker, chromogranin A has significant limitations. Multiple other biomarkers are in use, but most have not been studied well and need further validation before being recommended for clinical practice. We review both established and novel circulating biomarkers, and highlight some of the limitations of tumor marker use in patients with NETs.

Nonfunctional Pancreatic Neuroendocrine Tumors: Advances in Diagnosis, Management, and Controversies

In this article, we aimed to review the literature on the clinics and management of nonfunctional pancreatic neuroendocrine tumors (NPNET). Pancreatic neuroendocrine tumors (PNET) are rare tumors with a <1/100,000 incidence and constitute approximately 2 to 10% of all pancreatic tumors. Nonfunctional PNETs are difficult to detect at early stages since they have no symptoms. Except those detected accidentally during different diagnoses, the majority of PNETs are detected in the advanced stages, with symptoms related to tumor size or liver metastasis. We reviewed the studies published in the English medical literature through PubMed and summarized the clinical features and current approaches to the treatment and follow-up of the NPNET. The common imaging techniques used for the detection of tumor localization, size, locoregional, and metastatic involvement are contrasted computed tomography, magnetic resonance imaging, endoscopic ultrasonography, and somatostatin receptor scintigraphy. Surgical resection is the only curative treatment. However, in advanced locoregional disease and liver metastasis, interventive ablative therapies such as palliative reductive surgery, selective hepatic arterial embolization, radiofrequency ablation; and systemic therapies, such as peptide receptor radionuclide therapy, chemotherapy, somatostatin analogous therapy, interferon, VEGF inhibitor, and mTOR inhibitor may be used as symptom relieving or may improve progression-free survival and total survival. Current knowledge on NPNET shows that the treatment should be personalized considering the prognostic features and life expectancy of the patient.

Consensus Recommendations for the Diagnosis and Management of Pancreatic Neuroendocrine Tumors: Guidelines from a Canadian National Expert Group

Pancreatic neuroendocrine tumors (pNETs) are rare heterogeneous tumors that have been steadily increasing in both incidence and prevalence during the past few decades. Pancreatic NETs are categorized as functional (F) or nonfunctional (NF) based on their ability to secrete hormones that elicit clinically relevant symptoms. Specialized diagnostic tests are required for diagnosis. Treatment options are diverse and include surgical resection, intraarterial hepatic therapy, and peptide receptor radionuclide therapy (PRRT). Systemic therapy options include targeted agents as well as chemotherapy when indicated. Diagnosis and management should occur through a collaborative team of health care practitioners well-experienced in managing pNETs. Recent advances in pNET treatment options have led to the development of the Canadian consensus document described in this report. The discussion includes the epidemiology, classification, pathology, clinical presentation and prognosis, imaging and laboratory testing, medical and surgical management, and recommended treatment algorithms for pancreatic neuroendocrine cancers.

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.