Evolution of the diffuse neuroendocrine system--clear cells and cloudy origins

Investigating pulmonary neuroendocrine cells in human respiratory diseases with airway models

Despite accounting for only ∼0.5% of the lung epithelium, pulmonary neuroendocrine cells (PNECs) appear to play an outsized role in respiratory health and disease. Increased PNEC numbers have been reported in a variety of respiratory diseases, including chronic obstructive pulmonary disease and asthma. Moreover, PNECs are the primary cell of origin for lung neuroendocrine cancers, which account for 25% of aggressive lung cancers. Recent research has highlighted the crucial roles of PNECs in lung physiology, including in chemosensing, regeneration and immune regulation. Yet, little is known about the direct impact of PNECs on respiratory diseases. In this Review, we summarise the current associations of PNECs with lung pathologies, focusing on how new experimental disease models, such as organoids derived from human pluripotent stem cells or tissue stem cells, can help us to better understand the contribution of PNECs to respiratory diseases.

Advances in steroid research from the pioneering neurosteroid concept to metabolomics: New insights into pregnenolone function

Advances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.

Primary Pituitary Carcinoids Do Not Exist: A Reappraisal in the Era of Pituitary Neuroendocrine Tumours

The World Health Organization classification of pituitary tumours, published in 2022, supported a change in the terminology from "pituitary adenoma" to "pituitary neuroendocrine tumour" (PitNET). The neuroendocrine cells represent an integral part of the diffuse neuroendocrine system, including, among others, thyroid C cells, the parathyroid chief cells, and the anterior pituitary. Normal and neoplastic adenohypophyseal neuroendocrine cells have light microscopic, ultrastructural features and an immunoprofile compatible with the neuroendocrine cells and neuroendocrine tumours from other organs. Moreover, neuroendocrine cells of pituitary origin express transcription factors which indicate their cell-lineage origin. Thus, pituitary tumours are now considered as a continuum with other neuroendocrine tumours. PitNETs may occasionally be aggressive. In this context, the term "pituitary carcinoid" has no specific meaning: it either represents a PitNET, or a metastasis to the pituitary gland of a neuroendocrine tumour (NET). An accurate pathological evaluation, combined where necessary with functional radionuclide imaging, can define the origin of the tumour. We recommend that clinicians liaise with patient groups to understand the terminology to define primary tumours of adenohypophyseal cells. It is incumbent upon the responsible clinician to explain the use of the word "tumour" in a given clinical context.

How cancer hijacks the body's homeostasis through the neuroendocrine system

During oncogenesis, cancer not only escapes the body's regulatory mechanisms, but also gains the ability to affect local and systemic homeostasis. Specifically, tumors produce cytokines, immune mediators, classical neurotransmitters, hypothalamic and pituitary hormones, biogenic amines, melatonin, and glucocorticoids, as demonstrated in human and animal models of cancer. The tumor, through the release of these neurohormonal and immune mediators, can control the main neuroendocrine centers such as the hypothalamus, pituitary, adrenals, and thyroid to modulate body homeostasis through central regulatory axes. We hypothesize that the tumor-derived catecholamines, serotonin, melatonin, neuropeptides, and other neurotransmitters can affect body and brain functions. Bidirectional communication between local autonomic and sensory nerves and the tumor, with putative effects on the brain, is also envisioned. Overall, we propose that cancers can take control of the central neuroendocrine and immune systems to reset the body homeostasis in a mode favoring its expansion at the expense of the host.

All Together Now: Standardization of Nomenclature for Neuroendocrine Neoplasms across Multiple Organs

Neuroendocrine neoplasms (NENs) span virtually all organ systems and exhibit a broad spectrum of behavior, from indolent to highly aggressive. Historically, nomenclature and grading practices have varied widely across, and even within, organ systems. However, certain core features are recapitulated across anatomic sites, including characteristic morphology and the crucial role of proliferative activity in prognostication. A recent emphasis on unifying themes has driven an increasingly standardized approach to NEN classification, as delineated in the World Health Organization's Classification of Tumours series. Here, we review recent developments in NEN classification, with a focus on NENs of the pancreas and lungs.

Prospective Multicentric Assessment of 68Ga-DOTANOC PET/CT in Grade 1-2 GEP-NET

The aim of this multicentric study was to prospectively compare 68Ga-DOTANOC PET/CT versus somatostatin receptor scintigraphy (SRS) with SPECT/CT, combined with multiphasic CT scan and MRI in patients with grade 1 or 2 gastroenteropancreatic neuroendocrine tumors (GEP-NET). Patients with histologically proven grade 1 or 2 GEP-NET with suspicion of recurrence or progression, or with typical aspects of GEP-NET on morphological imaging, were explored with conventional imaging (CI): SRS with SPECT/CT, multiphasic CT scan and/or liver MRI followed by 68Ga-DOTANOC PET/CT. The gold standard was based on histology and imaging follow-up. The data of 105 patients (45 woman and 60 men; median age) were analyzed. 68Ga-DOTANOC PET/CT sensitivity was significantly higher than CI sensitivity in per-patient (98.9% vs. 88.6%, p = 0.016) and per-region (97.6% vs. 75.6%, p < 0.001) analyses, in the detection of the primary (97.9% vs. 78.7%; p = 0.016), peritoneal carcinomatosis (95% vs. 30%, p < 0.001), and bone metastases (100% vs. 33.3%, p = 0.041). 68Ga-DOTANOC PET/CT had an impact on the therapeutic management of 41.9% (44/105) patients compared to decisions based on CI explorations. Our data confirm the superiority of 68Ga-DOTANOC PET/CT over CI in the detection of peritoneal carcinomatosis and bone metastasis, as well as its strong therapeutic impact on the management of patients with grade 1-2 GEP-NETs.

Neuroendocrine Tumors: An Analysis of Prevalence, Incidence, and Survival in a Hospital-Based Study in Ecuador

Neuroendocrine tumors (NETs) represent a heterogeneous malignancy group of neoplasms, with a limited amount of data from Latin America. Thus, this observational study aimed to provide data about the prevalence, incidence, and survival rates for NET in Ecuadorian hospitals. The study was conducted using data from the Society for the Fight Against Cancer (SOLCA). We evaluated patients with NETs (2000−2020) using the HJ-Biplot method and Cox proportional hazards. Annual age-adjusted incidence and limited-duration prevalence in multivariable analyses as well as hazard ratios (HRs) for mortality and survival were obtained. In the years 2000−2020, the age-adjusted incidence rate increased by 9-fold in the stomach and by 7-fold in the breast. The incidence rates were 1.38 per 100,000 persons in the lung and at 1.79 per 100,000 persons in gastroenteropancreatic sites (rectum, stomach, and pancreas). The prevalence increased from 0.0027% in 2000 to 0.0736% in 2019 and 0.0245% in 2020. Overall survival was worse for metastatic NETs (HR, 4.061; 95% CI, 1.932−8.540; p < 0.001) and advanced local NETs (HR, 2.348; 95% CI, 1.007−5.475 p < 0.048) than for localized NETs. In conclusion, the NET incidence increased in the last 20 years and survival decreased over time, especially for metastatic tumors in the pancreas and the nostril.

Performance Evaluation of the KRYPTOR Compact PLUS Analyzer-Based B.R.A.H.M.S. CgA Ⅱ KRYPTOR Assay for Chromogranin A Measurement

Numerous immunoassays have been developed to measure the levels of chromogranin A (CgA), a useful biomarker for diagnosing and monitoring generally heterogeneous neuroendocrine tumors (NETs). Here, we evaluated the imprecision and linearity of three such assays: KRYPTOR (ThermoFisher Scientific), NEOLISA (EuroDiagnostica), and CgA-RIA (CisBio), using 123 samples for each assay. The correlation coefficients between the assays were 0.932 (CgA-RIA versus NEOLISA), 0.956 (KRYPTOR versus CgA-RIA), and 0.873 (NEOLISA versus KRYPTOR). KRYPTOR showed good precision, with percent coefficients of variation less than 5% for low and high concentration quality controls. Linearity was maintained over a wide concentration range. Comparison of CgA levels from three disease entities (NETs, non-NET pancreatic tumors, and prostate cancer) and healthy controls showed that patients with NETs had significantly higher CgA levels (n = 57, mean: 1.82 ± 0.43 log ng/mL) than healthy individuals (n = 20, mean: 1.51 ± 0.23 log ng/mL; p = 0.018). No other significant differences between groups were observed. All three immunoassays showed strong correlations in measured CgA levels. Because KRYPTOR operation uses a fully automated random-access system and requires shorter incubation times and smaller sample volumes, the KRYPTOR assay may improve laboratory workflow while maintaining satisfactory analytical performance.

Stress and the "extended" autonomic system

This review updates three key concepts of autonomic neuroscience-stress, the autonomic nervous system (ANS), and homeostasis. Hans Selye popularized stress as a scientific idea. He defined stress variously as a stereotyped response pattern, a state that evokes this pattern, or a stimulus that evokes the state. According to the "homeostat" theory stress is a condition where a comparator senses a discrepancy between sensed afferent input and a response algorithm, the integrated error signal eliciting specific patterns of altered effector outflows. Scientific advances since Langley's definition of the ANS have incited the proposal here of the "extended autonomic system," or EAS, for three reasons. (1) Several neuroendocrine systems are bound inextricably to Langley's ANS. The first to be described, by Cannon in the early 1900s, involves the hormone adrenaline, the main effector chemical of the sympathetic adrenergic system. Other neuroendocrine systems are the hypothalamic-pituitary-adrenocortical system, the arginine vasopressin system, and the renin-angiotensin-aldosterone system. (2) An evolving body of research links the ANS complexly with inflammatory/immune systems, including vagal anti-inflammatory and catecholamine-related inflammasomal components. (3) A hierarchical network of brain centers (the central autonomic network, CAN) regulates ANS outflows. Embedded within the CAN is the central stress system conceptualized by Chrousos and Gold. According to the allostasis concept, homeostatic input-output curves can be altered in an anticipatory, feed-forward manner; and prolonged or inappropriate allostatic adjustments increase wear-and-tear (allostatic load), resulting in chronic, stress-related, multi-system disorders. This review concludes with sections on clinical and therapeutic implications of the updated concepts offered here.

Time to give up traditional methods for the management of gastrointestinal neuroendocrine tumours

Neuroendocrine tumors (NETs) are a rare and heterogeneous disease group and constitute 0.5% of all malignancies. The annual incidence of NETs is increasing worldwide. The reason for the increase in the incidence of NETs is the detection of benign lesions, incidental detection due to the highest use of endoscopic and imaging procedures, and higher recognition rates of pathologists. There have been exciting developments regarding NET biology in recent years. Among these, first of all, somatostatin receptors and downstream pathways in neuroendocrine cells have been found to be important regulatory mechanisms for protein synthesis, hormone secretion, and proliferation. Subsequently, activation of the mammalian target of rapamycin pathway was found to be an important mechanism in angiogenesis and tumor survival and cell metabolism. Finally, the importance of proangiogenic factors (platelet-derived growth factor, vascular endothelial growth factor, fibroblastic growth factor, angiopoietin, and semaphorins) in the progression of NET has been determined. Using the combination of biomarkers and imaging methods allows early evaluation of the appropriateness of treatment and response to treatment.

Serum neuron-specific enolase: A promising biomarker of silicosis

BACKGROUND

Silicosis is a type of chronic pulmonary fibrosis caused by long-term inhalation of silica dust particles. There has been no ideal biomarker for the diagnosis and differential diagnosis of silicosis until now. Studies have found that elevated neuron-specific enolase (NSE) concentration in the serum of silicosis patients is helpful for diagnosis and severity assessment of the disease. However, the number of cases in these studies was not enough to arouse attention.

AIM

To investigate the clinical significance of serum NSE in the diagnosis and staging of silicosis.

METHODS

From January 2017 to June 2019, 326 cases of silicosis confirmed in Quanzhou First Hospital Affiliated to Fujian Medical University were included in the silicosis group. A total of 328 healthy individuals or medical patients without silicosis were included in the control group. Serum NSE concentrations of all subjects were determined by electrochemical luminescence.

RESULTS

There were no significant differences in sex, age, smoking index and complications between the silicosis and control groups. The mean serum NSE concentration was 26.57 ± 20.95 ng/mL in the silicosis group and 12.42 ± 2.68 ng/mL in the control group. The difference between the two groups was significant (U = 15187, P = 0.000). Among the 326 patients with silicosis, 103 had stage I silicosis, and the mean serum NSE concentration was 15.55 ± 6.23 ng/mL. The mean serum NSE concentration was 21.85 ± 12.05 ng/mL in 70 patients with stage II silicosis. The mean serum NSE concentration was 36.14 ± 25.72 ng/mL in 153 patients with stage III silicosis. Kruskal–Wallis H test suggested that the difference in serum NSE concentration in silicosis patients in the three groups was significant (H = 130.196, P = 0.000). Receiver operating characteristic curve analysis indicated that the area under the curve was 0.858 (95% confidence interval: 0.828-0.888; P = 0.000). When the NSE concentration was 15.82 ng/mL, the Jorden index was the largest, the sensitivity was 72%, and the specificity was 90%.

CONCLUSION

Serum NSE concentration may be a promising biomarker for the diagnosis and assessment of severity of silicosis.

Historical account of endocrinal disorders in Unani medicine

Hippocratic doctrine of four humors and qualities is implicated to be a pioneer of modern endocrinology because of the concept of dyscrasia. Imbalance in humors causes disease. Unani scholars were aware of endocrinological disorders like endocrinologic syndrome (i.e., association of amenorrhea and galactorrhoea in a non-pregnant woman), castration, contraceptives techniques, infertility, obesity, diabetes etc., and also their mode of remedy, albeit with a phenomenological approach. Their understanding of the symptoms and signs related to endocrinologic syndromes, which were explained in detail in the recent account of the endocrine system, is presented here with historical chronology. The survey was carried out from the literature of the Unani system of medicine, and the same was analyzed from the observations reported in various indexed journals and reputed books. The paper details the account of endocrinologic syndrome from the Greek era to the end of the medieval ages. - Description of the endocrinal disorders is mentioned in Unani Medicine for centuries, albeit with a different name for the disease category.- According to Unani Medicine, this disease arises due to abnormal quality and quantity of humour.- Renowned Unani scholars like Hippocrates (370-460 BC), Aristotle (384-322 BC), Aretaeos of Kappadokia(81-96 AD), Galen (130-200 AD), Zakaria Razi (865-925 AD), Majusi (930-994 AD), Ibn-e-Sina (980-1037 AD), Albucasis (1013-1106 AD) and Ismail Jorjani (1042-1137 AD) also treated such ailments through Unani medicine (plant, mineral and animal origin drugs).-Majusi performed surgery of Goiter and mentioned in his treatise and recommended the method of surgery.-Albucasis performed the first successful thyroidectomy under opium (Papaver somniferum L.) sedation and simple ligatures and hot cautery in the name of 'elephantiasis' of the throat (goiter).- The principles of treatment in Unani medicine may provide a guide for better management of endocrinal disorders (e.g., hypothyroidism, hyperthyroidism, diabetes etc.).- The treatment in Unani medicine for various diseases/syndromes/signs, which are now likely associated with hormone dysfunction, can open up the new field of Unani therapeutics for these diseases for the exploration of better treatment options.

Pulmonary neuroendocrine cells: physiology, tissue homeostasis and disease

Mammalian lungs have the ability to recognize external environments by sensing different compounds in inhaled air. Pulmonary neuroendocrine cells (PNECs) are rare, multi-functional epithelial cells currently garnering attention as intrapulmonary sensors; PNECs can detect hypoxic conditions through chemoreception. Because PNEC overactivation has been reported in patients suffering from respiratory diseases – such as asthma, chronic obstructive pulmonary disease, bronchopulmonary dysplasia and other congenital diseases – an improved understanding of the fundamental characteristics of PNECs is becoming crucial in pulmonary biology and pathology. During the past decade, murine genetics and disease models revealed the involvement of PNECs in lung ventilation dynamics, mechanosensing and the type 2 immune responses. Single-cell RNA sequencing further unveiled heterogeneous gene expression profiles in the PNEC population and revealed that a small number of PNECs undergo reprogramming during regeneration. Aberrant large clusters of PNECs have been observed in neuroendocrine tumors, including small-cell lung cancer (SCLC). Modern innovation of imaging analyses has enabled the discovery of dynamic migratory behaviors of PNECs during airway development, perhaps relating to SCLC malignancy. This Review summarizes the findings from research on PNECs, along with novel knowledge about their function. In addition, it thoroughly addresses the relevant questions concerning the molecular pathology of pulmonary diseases and related therapeutic approaches.

Summary: This Review highlights the physiological relevance of pulmonary neuroendocrine cells, rare airway epithelial cells that form intrapulmonary sensory organs, abnormalities of which are associated with several pulmonary disorders, such as asthma and lung cancer.

The extended autonomic system, dyshomeostasis, and COVID-19

The pandemic viral illness COVID-19 is especially life-threatening in the elderly and in those with any of a variety of chronic medical conditions. This essay explores the possibility that the heightened risk may involve activation of the “extended autonomic system” (EAS). Traditionally, the autonomic nervous system has been viewed as consisting of the sympathetic nervous system, the parasympathetic nervous system, and the enteric nervous system. Over the past century, however, neuroendocrine and neuroimmune systems have come to the fore, justifying expansion of the meaning of “autonomic.” Additional facets include the sympathetic adrenergic system, for which adrenaline is the key effector; the hypothalamic-pituitary-adrenocortical axis; arginine vasopressin (synonymous with anti-diuretic hormone); the renin-angiotensin-aldosterone system, with angiotensin II and aldosterone the main effectors; and cholinergic anti-inflammatory and sympathetic inflammasomal pathways. A hierarchical brain network—the “central autonomic network”—regulates these systems; embedded within it are components of the Chrousos/Gold “stress system.” Acute, coordinated alterations in homeostatic settings (allostasis) can be crucial for surviving stressors such as traumatic hemorrhage, asphyxiation, and sepsis, which throughout human evolution have threatened homeostasis; however, intense or long-term EAS activation may cause harm. While required for appropriate responses in emergencies, EAS activation in the setting of chronically decreased homeostatic efficiencies (dyshomeostasis) may reduce thresholds for induction of destabilizing, lethal vicious cycles. Testable hypotheses derived from these concepts are that biomarkers of EAS activation correlate with clinical and pathophysiologic data and predict outcome in COVID-19 and that treatments targeting specific abnormalities identified in individual patients may be beneficial.

C-reactive protein may be a prognostic factor for the whole gastroenteropancreatic neuroendocrine tumor group

BACKGROUND

Long non-coding RNAs (lncRNAs) are a kind of single-stranded RNA of more than 200 nucleotides in length and have no protein-coding function. Amounting studies have indicated that lncRNAs could play a vital role in the initiation and development of cancers, including gastric cancer (GC). Considering the crucial functions of lncRNAs, the identification and exploration of novel lncRNAs in GC is necessary.

AIM

To identify independent prognostic markers for the whole gastroenteropancreatic neuroendocrine tumor (GEP-NET) group.

METHODS

Ninety-three patients diagnosed with GEP-NETs within a specified period were included in this study. Patient data were retrospectively analyzed. The relationships between all independent variables and 5-year survival status calculated during the follow-up period (months) were assessed. In addition, the relationships between the independent variables were investigated.

RESULTS

When 5-year survival rate was compared, a statistically significant relationship between the age at diagnosis, male gender, tumor size, tumor stage, liver and/or distant metastasis, and tumor grade determined by the Ki-67 level and mitotic count, and the level of C-reactive protein (CRP), was observed. The mean survival (overall survival) of the study group was 102.5 ± 6.3 (SD) mo. The percentages of 1, 3 and 5-year survival were 90%, 72%, and 61%, respectively. In 63 of 93 patients, Ki-67 and the mitotic count determined the same grade. The Ki-67 levels in 29 patients and the mitotic count in only 1 patient were in the higher grade. The risk of death increased by 4% for every 1 year increase at the diagnosis age and was 2.0-fold higher for male patients, 3.0-fold higher for G3 according to the mitotic count, 3.7-fold higher for G3 according to the Ki-67 level, 12.7-fold higher for cases with tumor stage 3 or 4 by a 1 cm increase in the ratio of 9% in tumor size, and 6.1-fold higher for patients with liver metastasis for every 1 mg/dL increase in the ratio of 1.5% in CRP level. There was a significant difference between pancreatic and stomach NETs in favor of stomach tumors in terms of survival.

CONCLUSION

Tumor site, stage, grade and Ki-67 level affected patient survival, and it was observed that CRP affected disease progression (particularly if it was > 20 mg/dL). However, a relationship between surgical resection of the lesion and survival was not shown. Larger scale prospective studies are required to determine whether CRP level may be a poor prognostic factor for the entire GEP-NET group.

Neuroendocrine Neoplasms: Dichotomy, Origin and Classifications

Neuroendocrine neoplasms (NENs) are heterogeneous tumors with a common phenotype. There are two fundamentally different groups of NENs: well-differentiated, low-proliferating NENs, called neuroendocrine tumors (NETs) or carcinoids, and poorly differentiated, highly proliferating NENs, called small- or large-cell neuroendocrine carcinomas (NECs). This NEN dichotomy is probably due to an origin from different neuroendocrine progenitor cells. The current World Health Organization (WHO) classification of gastrointestinal NENs uses the Ki67 proliferation index to grade NETs as G1 or G2, and NECs as G3. In the pancreas, NETs and NECs may overlap in their proliferation index, making the distinction between them difficult and leading to therapeutic uncertainties. Therefore, the WHO classification of pancreatic NENs (PanNENs) from 2017 introduced a new NET G3 category. Helpful for the distinction of NETs G3 from NECs is the expression of p53 and rb1 that is usually negative in PanNETs. Comparison of the WHO classification of digestive system NENs with other NEN classifications reveals site-specific differences in terminology and a general lack of grading systems. However, all classifications recognize the existence of the two major NEN families and provide a general basis for their prognostic and therapeutic stratification. A development of a common NEN classification across organs is desirable.

Metronomic and metronomic-like therapies in neuroendocrine tumors - Rationale and clinical perspectives

Metronomic therapy is characterized by the administration of regular low doses of certain drugs with very low toxicity. There have been numerous debates over the empirical approach of this regimen, but fewest side effects are always something to consider in order to improve patients' quality of life. Neuroendocrine tumors (NETs) are rare malignancies relatively slow-growing; therefore their treatment is often chronic, involving several different therapies for tumor growth control. Knowing that these tumors are highly vascularized, the anti-angiogenic aspect is highly regarded as something to be targeted in all patients harboring NETs. Additionally the metronomic schedule has proved to be effective on an immunological level, rendering this approach as a multi-targeted therapy. Rationalizing that advanced NETs are in many cases a chronic disease, with which patients can live for as long as possible, a systemic therapy with regular low doses and a very low toxicity is in many cases a judicious manner of pursuing stabilization. Metronomic schedule is usually correlated with chemotherapy in oncology, but other therapies, such as radiotherapy and biotherapy can be delivered in a metronomic like manner. This review describes clinical trials and case series involving metronomic therapies alone or in combination in patients with advanced NETs. Nowadays level of evidence about metronomic therapy in NETs is quite low, therefore future prospective clinical studies are needed to validate the metronomic approach in specific clinical settings.

Large-Cell Neuroendocrine Carcinoma of the Esophagus: A Case from Saudi Arabia

Neuroendocrine carcinomas of the esophagus are very rare, and the majority are high grade (poorly differentiated). They occur most frequently in males in their sixth and seventh decades of life. There have been no concrete data published on clinical features or on prognosis. We report a case of large-cell neuroendocrine carcinoma of the esophagus in a 66-year-old Saudi female with progressive dysphagia and weight loss. Upper endoscopy revealed an esophageal ulcerated mass.

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.

Neuroendocrine tumours of the small intestine

The prevalence of intestinal neuroendocrine tumours, also known as carcinoid tumours, has increased significantly over the past three decades. Tumours of the distal small intestine (midgut) are often indolent, but are characterized by a high potential to metastasize to the small-bowel mesentery and liver. Patients with distant metastases are prone to development of the carcinoid syndrome, a constellation of symptoms which includes flushing, diarrhoea, and valvular heart disease. The carcinoid syndrome is caused by secretion of serotonin and other vasoactive substances into the systemic circulation. Treatment options for metastatic intestinal NETs have expanded in recent years. Of particular importance has been the development of somatostatin-analogue therapies. Somatostatin analogues were originally introduced for palliation of the carcinoid syndrome; however recent clinical trials have demonstrated that they can exert an inhibitory effect on tumour growth. Other novel agents targeting the VEGF and mTOR pathways have recently been evaluated in phase III trials, however their role in the management of small-intestinal NETs remains controversial. This article examines the biological characteristics of small intestinal NETs, summarizes current guidelines on classification, staging and grading, and reviews developments in locoregional and systemic therapy.

Anti-tumor effects of the Notch pathway in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are driven by gain-of-function mutations of KIT or PDGFRa. The introduction of imatinib has significantly extended survival for patients. However, most patients develop resistances. Notch signaling is a conserved developmental pathway known to play a critical role in the development of several cancers, functioning as a tumor promoter or a tumor suppressor. Given that the normal progenitor cell for GIST, the interstitial cell of Cajal, has characteristics similar to those of cells of neuroendocrine origin, we hypothesized that Notch pathway impacts the biology of GIST cells. In this study, we retrovirally and pharmacologically manipulated the Notch pathway in human GIST cells. We also performed a retrospective analysis of a cohort on 15 primary tumors to determine the role of Hes1, a major target gene of Notch, as a prognostic marker for GIST. Constitutively, active intracellular domain of Notch1 (ICN1) expression potently induced growth arrest and downregulated KIT expression in vitro. Additionally, treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid caused dose-dependent upregulation of Notch1 expression and a parallel decrease in viability in these cells. Retroviral silencing of downstream targets of Notch (dominant-negative Hes1) and pharmacological inhibition of Notch activation (γ-secretase inhibition) partially rescued GIST cells from suberoylanilide hydroxamic acid treatment. GIST patients with high Hes1 mRNA levels have a significantly longer relapse-free survival. These results identify a novel anti-tumor effect of Notch1 and cross talk between the Notch and KIT pathways. Thus, activation of this pathway by treatment with histone deacetylase inhibitors is an appealing potential therapeutic strategy for GISTs. Précis: This study is the first report of the tumor suppressor effects of Notch pathway in gastrointestinal stromal tumors via a negative feedback with the oncogene KIT and may lead the development of new therapeutic strategies for GISTs patients.

The enteroendocrine "letter cells" - time for a new nomenclature?

Abstract The endocrine cells of the gastrointestinal (GI) tract and the pancreas, referred to as the enteroendocrine cells, secrete a large variety of peptides and amines that regulate functions of the digestive tract itself and of distant organs. Taken together, the enteroendocrine cells form the largest system of endocrine cells in the body, presently comprising 16 cell types. Many of them have been named after letters of the alphabet, but the names are only occasionally related to morphological or functional characteristics of the cell. In this review of the normal, adult, mammalian enteroendocrine cells, we summarize synonyms, functions, locations, structure, stored hormones/amines, receptors, and other cellular expressions. We propose that the enteroendocrine cells should be renamed after their most well-known hormone/amine and, when applicable, their anatomical location, with opportunities for future revisions.

[Gastric neuroendocrine tumors. Endoscopic and surgical treatment]

Neuroendocrine tumors (NETs) of the stomach are the most frequent among all neuroendocrine neoplasms in the digestive tract. The diagnosis and classification are complicated by the fact that these tumors have to be categorized not only by common staging and grading but also according to their pathophysiological background (types). The types differ in their biological behaviour (aggressiveness) which influences therapeutic concepts. This article explains and summarizes the etiology and classification of gastric NETs and offers a precise concept for diagnosis and treatment to improve clinical outcome.

Neuroendocrine tumors in children and young adults: rare or not so rare

This review focuses on neuroendocrine tumors (NETs) that arise in the diffuse neuroendocrine system; these rare tumors can develop in any organ that has dispersed single endocrine cells, for example, the intestine, or in an organ that has clusters of endocrine cells, for example, pancreatic islets. Previously considered benign, NETs are now recognized to recur locally or metastasize to liver and bone if not completely excised early in their course of development. This article summarizes the epidemiology and reviews the diagnostic and therapeutic challenges of NETs in children and youth, noting especially those NETs that are more prevalent in young people than in older adults.

The clinical relevance of chromogranin A as a biomarker for gastroenteropancreatic neuroendocrine tumors

Chromogranin A, although it exhibits limitations, is currently the most useful general tumor biomarker available for use in the diagnosis and management of gastroenteropancreatic neuroendocrine tumors (NETs). The value of the chromogranin A lies in its universal cosecretion by the majority of neuroendocrine cells that persists after malignant transformation. Clinicians aware of the physiologic role of chromogranin A and its secretion in a variety of non-NET-related pathologic conditions can use this protein as a moderately effective tumor biomarker in the management of GEP-NETs.

Incidence, survival, and prevalence of neuroendocrine tumors versus neuroblastoma in children and young adults: nine standard SEER registries, 1975-2006

BACKGROUND

The incidence, survival, and prevalence of neuroendocrine tumors (NETs) in children were determined as a first step in improving diagnosis and therapy. Outcomes were compared with neuroblastoma, a pediatric malignancy that shares several biomarkers.

METHODS

Incidence rates, observed survival rates and 31-year limited duration prevalence counts were obtained from SEER*Stat for diagnosis years 1975 to 2006. These rates were compared between and within NETs and neuroblastoma for demographic and tumor-related variables from nine standard SEER registries for ages 0-29 years. Multivariate Cox regression was performed to identify prognostic factors for survival in NETs.

RESULTS

The number of NETs was 1,073 compared to 1,664 neuroblastomas. The most common NET sites were lung, breast, and appendix. NET 5-year observed survival rates increased from 83% between 1975 and 1979 to 84% for the 2000-2006 period, while analogous neuroblastoma survival rates steadily increased from 45-73%. Five-year observed survival was less than 30% in females with NETs of the cervix and ovary. The estimated 31-year limited duration prevalence for NETs as of January 1, 2006 in the U.S. population was 7,724 compared to 9,960 for neuroblastomas. Age-adjusted multivariate Cox Regression demonstrated small cell histology, primary location in the breast, and distant stage as major predictors of decreased survival.

CONCLUSIONS

While survivorship has significantly increased for neuroblastoma, those diagnosed with NETs have shown no increase in survival during this 31-year period. NETs constitute an unrecognized cancer threat to children and young adults comparable to neuroblastoma in both number of affected persons and disease severity.

The history and development of the gastroenteropancreatic endocrine axis

Fundamental medical principles, such as hormone action, distant physiologic regulation, and ductless secretion were once mysteries. They now form the basis of basic medical diagnostics and therapeutics. This article discusses and reviews the rich history that served as the foundation of modern medicine, from the early descriptions of tumors, to the discovery of hormones and assays, and how they resulted in the treatments available today.

Conserved genetic pathways controlling the development of the diffuse endocrine system in vertebrates and Drosophila

The midgut epithelium is formed by absorptive enterocytes, secretory cells and endocrine cells. Each of these lineages is derived from the pluripotent progenitors that constitute the embryonic endoderm; the mature midgut retains pools of self-renewing stem cells that continue to produce all lineages. Recent findings in vertebrates and Drosophila shed light on the genetic mechanism that specifies the fate of the different lineages. A pivotal role is played by the Notch signaling pathway that, in a manner that appears to be very similar to the way in which Notch signaling selects neural progenitors within the neurectoderm, distinguishes the fate of secretory/endocrine cells and enterocytes. Proneural genes encoding bHLH transcription factors are expressed and required in prospective endocrine cells; activation of the Notch pathways restricts the number of these cells and promotes enterocyte development. In this review we compare the development of the intestinal endocrine cells in vertebrates and insects and summarize recent findings dealing with genetic pathways controlling this cell type.

Chromogranin A--biological function and clinical utility in neuro endocrine tumor disease

BACKGROUND

Neuroendocrine tumors (NETs) are a form of cancer that differ from other neoplasia in that they synthesize, store, and secrete peptides, e.g., chromogranin A (CgA) and amines. A critical issue is late diagnosis due to failure to identify symptoms or to establish the biochemical diagnosis. We review here the utility of CgA measurement in NETs and describe its biological role and the clinical value of its measurement.

METHODS

Literature review and analysis of the utility of plasma/serum CgA measurements in NETs and other diseases.

RESULTS

CgA is a member of the chromogranin family; its transcription and peptide processing are well characterized, but its precise function remains unknown. Levels are detectable in the circulation but vary substantially (approximately 25%) depending on which assay is used. Serum and plasma measurements are concordant. CgA is elevated in approximately 90% of gut NETs and correlates with tumor burden and recurrence. Highest values are noted in ileal NETs and gastrointestinal NETs associated with multiple endocrine neoplasia type 1. Both functioning and nonfunctioning pancreatic NETs have elevated values. CgA is more frequently elevated in well-differentiated tumors compared to poorly differentiated NETs. Effective treatment is often associated with decrease in CgA levels. Proton pump inhibitors falsely increase CgA, but levels normalize with therapy cessation.

CONCLUSIONS

CgA is currently the best available biomarker for the diagnosis of NETs. It is critical to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy. Measurement of plasma CgA is mandatory for the effective diagnosis and management of NET disease.

Oberndorfer and his successors: from carcinoid to neuroendocrine carcinoma

The year 2007 the centenary of Siegfried Oberndorfer's seminal description of special tumors of the small intestine which he called "Karzinoide Tumoren" (carcinoids). Their endocrine nature was suggested by Pierre Masson in 1914. The work of Friedrich Feyrter and later Anthony Pearse established the concept of a diffuse endocrine cell system. They suggested that there is a family of endocrine cells whose members originate at different sites in the organism and give rise to similar tumors, the carcinoids. Subsequent studies revealed that the individual members of the endocrine cell system are distinguished from each other by the expression of specific polypeptides (i.e., hormones). Common to all of these cells is the expression of general markers such as synaptophysin and chromogranin A. This led to the term neuroendocrine cell system and consequently neuroendocrine tumor. Although many tumors are similar in histological appearance, biologically they show heterogeneity, which has important implications for treatment. Therefore, efforts have been made to define the neuroendocrine neoplasms on the basis of features that discriminate the tumors with almost no risk/low risk of malignancy from low-grade and high-grade malignant tumors. For the gastroenteropancreatic neuroendocrine tumors, this resulted in a new World Health Organization classification that was recently followed by a tumor-nodes-metastasis classification.