Rectal neuroendocrine tumours and the role of emerging endoscopic techniques

Rectal neuroendocrine tumours represent a rare colorectal tumour with a 10 fold increased prevalence due to incidental detection in the era of colorectal screening.Patient outcomes with early diagnosis are excellent.However endoscopic recognition of this lesion is variable and misdiagnosis can result in suboptimal endoscopic resection with subsequent uncertainty in relation to optimal long-term management.Endoscopic techniques have shown particular utility in managing this under-recognized neuroendocrine tumour.

Nonfunctional pancreatic neuroendocrine tumours misdiagnosed as autoimmune pancreatitis:A case report and review of literature

BACKGROUND Nonfunctional pancreatic neuroendocrine tumours are difficult to diagnose in the early stage of disease due to a lack of clinical symptoms,but they can rarely manifest as autoimmune pancreatitis.Autoimmune pancreatitis is an uncommon disease that may cause recurrent acute pancreatitis and is therefore often regarded as a special type of chronic pancreatitis.CASE SUMMARY We report a case of a 42-year-old female who had nonspecific upper abdominal pain for 4 years and radiological abnormalities of the pancreas that mimicked autoimmune pancreatitis.The symptoms and pancreatic imaging did not improve following 1 year of steroid therapy.Finally,pancreatic biopsy was performed through endoscopic ultrasonography-guided fine-needle aspiration biopsy,and nonfunctional pancreatic neuroendocrine tumours were ultimately diagnosed.Pancreatectomy has resolved her symptoms.CONCLUSION Therefore,the differentiation of nonfunctional pancreatic neuroendocrine tumours from autoimmune pancreatitis is very important,although it is rare.We propose that endoscopic ultrasonography-guided fine-needle aspiration biopsy should be performed if imaging characteristics are equivocal or the diagnosis is in question.

Clinicopathological characteristics and prognosis of 77 cases with type 3 gastric neuroendocrine tumours

BACKGROUND For the rarity of type 3 gastric neuroendocrine tumours(g-NETs),their clinicopathological characteristics and prognosis are not well illustrated.AIM To describe the clinicopathological features and outcome of type 3 g-NETs in the Chinese population.METHODS Based on the 2019 WHO pathological classification,the clinicopathological characteristics and prognosis of patients with type 3 g-NETs in China were retrospectively analysed.RESULTS A total of 77 patients(55.8%of females)with type 3 g-NETs were analysed,with a median age of 48 years(range:28-79 years).The tumours were mainly located in the gastric fundus/body(83.1%)and were mostly solitary(83.1%),with a median size of 1.5 cm(0.8-3.5 cm).Of these,there were 37 G1 tumours(48.1%),31 G2(40.3%),and 9 G3(11.7%).Ten(13.0%)and 24(31.2%)patients had lymph node and distant metastasis,respectively.In addition,type 3 g-NETs were heterogeneous.Compared with G1 NETs,G2 NETs had a higher lymph node metastasis rate,and G3 NETs had a higher distant metastasis rate.G1 and G2 NETs with stage I/II disease(33/68)received endoscopic treatment,and no tumour recurrence or tumour-related death was observed within a median follow-up time of 36 mo.Grade and distant metastasis were identified to be independent risk factors for prognosis in multivariable analysis.CONCLUSION Type 3 g-NETs are obviously heterogeneous,and the updated WHO 2019 pathological classification may be used to effectively evaluate their biological behaviors and prognosis.Also,endoscopic treatment should be considered for small(<2 cm),low grade,superficial tumours.

Advanced small-bowel well-differentiated neuroendocrine tumours:An international survey of practice on 3rd-line treatment

BACKGROUND Somatostatin analogues are an established first-line therapy for well differentiated small bowel neuroendocrine tumours(Wd-SBNETs),while and peptide receptor radionuclide therapy(PRRT)is frequently used as a second-line therapy.Adequate treatment selection of third-line treatment remains challenging due to the limited prospective data currently available on the best therapeutic sequence.AIM To understand current practice and rationale for decision-making by physicians in the 3rd-line setting by building an online survey.METHODS Weighted average(WA)of likelihood of usage between responders(1 very unlikely;4 very likely)was used to reflect the relevance of factors explored.RESULTS Replies from representatives of 28 centers were received(5/8/2020-21/9/2020);medical oncologist(53.6%),gastroenterologist(17.9%);United Kingdom(21.4%),Spain(17.9%),Italy(14.3%).Majority from European Neuroendocrine Tumor Society(ENETS)Centres of Excellence(57.1%),who followed ENETS guidelines(82.1%).Generally speaking,3rd-line treatment for Wd-SBNETs was:everolimus(EVE)(66.7%),PRRT(18.5%),liver embolization(LE)(7.4%)and interferon-alpha(IFN)(3.7%);chemotherapy(0%);decision was based on clinical trial data(59.3%),or personal experience(22.2%).EVE was most likely used if Ki-67<10%(WA 3.27/4)or age<70 years(WA 3.23/4),in the 3rd-line setting(WA 3.23/4);regardless of presence/absence of carcinoid syndrome(CS),rate of progression or extent of disease.Chemotherapy was mainly utilised only if rapid progression(within 6 mo)(WA 3.35/4),Ki-6710%-20%(WA 2.77/4),negative somatostatin receptor imaging(WA 2.65/4)or high tumour burden(WA 2.77/4);temozolomide or streptozocin was used with capecitabine or 5-fluorouracil(5-FU)(57.7%),FOLFOX(5-FU combined with oxaliplatin)(23.1%).LE was selected if presence of CS(WA 3.24/4)or Ki-67<10%(WA 2.8/4),after progression to other treatments(WA 2.8/4).IFN was rarely used(WA 1.3/4).CONCLUSION Everolimus was the most frequently used therapeutic option in the third-line setting.The most important factors for decision-making included Ki-67,rate of progression,functionality and tumour burden;since this decision is based on multiple factors,it highlights the need for a multidisciplinary assessment.

Differential diagnosis of diarrhoea in patients with neuroendocrine tumours: A systematic review

BACKGROUND Approximately 20%of patients with neuroendocrine tumours(NETs)develop carcinoid syndrome(CS),characterised by flushing and diarrhoea.Somatostatin analogues or telotristat can be used to control symptoms of CS through inhibition of serotonin secretion.Although CS is often the cause of diarrhoea among patients with gastroenteropancreatic NETs(GEP-NETs),other causes to consider include pancreatic enzyme insufficiency(PEI),bile acid malabsorption and small intestinal bacterial overgrowth.If other causes of diarrhoea unrelated to serotonin secretion are mistaken for CS diarrhoea,these treatments may be ineffective against the diarrhoea,risking detrimental effects to patient quality of life.AIM To identify and synthesise qualitative and quantitative evidence relating to the differential diagnosis of diarrhoea in patients with GEP-NETs.METHODS Electronic databases(MEDLINE,Embase and the Cochrane Library)were searched from inception to September 12,2018 using terms for NETs and diarrhoea.Congresses,systematic literature review bibliographies and included articles were also hand-searched.Any study designs and publication types were eligible for inclusion if relevant data on a cause(s)of diarrhoea in patients with GEP-NETs were reported.Studies were screened by two independent reviewers at abstract and full-text stages.Framework synthesis was adapted to synthesise quantitative and qualitative data.The definition of qualitative data was expanded to include all textual data in any section of relevant publications.RESULTS Forty-seven publications(44 studies)were included,comprising a variety of publication types,including observational studies,reviews,guidelines,case reports,interventional studies,and opinion pieces.Most reported on PEI on/after treatment with somatostatin analogs;9.5%-84%of patients with GEP-NETs had experienced steatorrhoea or confirmed PEI.Where reported,14.3%–50.7%of patients received pancreatic enzyme replacement therapy.Other causes of diarrhoea reported in patients with GEP-NETs included bile acid malabsorption(80%),small intestinal bacterial overgrowth(23.6%-62%),colitis(20%)and infection(7.1%).Diagnostic approaches included faecal elastase,breath tests,tauroselcholic(selenium-75)acid(SeHCAT)scan and stool culture,although evidence on the effectiveness or diagnostic accuracy of these approaches was limited.Assessment of patient history or diarrhoea characteristics was also reported as initial approaches for investigation.From the identified evidence,if diarrhoea is assumed to be CS diarrhoea,consequences include uncontrolled diarrhoea,malnutrition,and perceived ineffectiveness of CS treatment.Approaches for facilitating differential diagnosis of diarrhoea include improving patient and clinician awareness of non-CS causes and involvement of a multidisciplinary clinical team,including gastroenterologists.CONCLUSION Diarrhoea in GEP-NETs can be multifactorial with misdiagnosis leading to delayed patient recovery and inefficient resource use.This systematic literature review highlights gaps for further research on prevalence of non-CS diarrhoea and suitability of diagnostic approaches,to determine an effective algorithm for differential diagnosis of GEP-NET diarrhoea.

Neuroendocrine tumour of the descending part of the duodenum complicated with schwannoma:A case report

BACKGROUND No known case of neuroendocrine tumour(NET)with schwannoma has been reported.CASE SUMMARY A 63-year-old female presented to our hospital with nausea and vomiting.Upper gastrointestinal endoscopy revealed a mass in the descending part of the duodenum.Using ultrasound gastroscopy,we found that the tumour originated from the submucosa and showed low echo.We removed the tumour by electrocoagulation and sent it for pathological biopsy.CONCLUSION Immunohistochemical results showed that the mass was a rare NET with neurilemmoma.

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.

Novel gold nanoparticles targeting somatostatin receptor subtype two with near-infrared light for neuroendocrine tumour therapy

Neuroendocrine tumours(NETs)are rare cancers with positive somatostatin receptor 2(SSTR2)expression,and treatment strategies for NETs are not satisfactory.Nanomaterial-mediated therapy targeting SSTR2 in NETs is very promising.This study firstly combined mesoporous silica-coated gold nanorods(AuNRs@mSiO_(2))and targeting-SSTR2 dodecane tetraacetic acidtyrosine3-octreotate(DOTA-TATE)into AuNRs@mSiO_(2)@DOTA-TATE to investigate NETs inhibition under near-infrared light.AuNRs@mSiO_(2)@DOTA-TATE showed good photothermal conversion efficiency.In vitro,under light irradiation,the cell viability significantly decreased with increasing AuNR@mSiO_(2)@DOTA-TATE concentration;in two successfully established neuroendocrine tumour organoids with SSTR2 expression,AuNRs@mSiO_(2)@DOTA-TATE with light inhibited tumours significantly better than AuNRs@mSiO_(2) with light.In vivo,the SSTR2-targeting ability and biodistribution of AuNRs@mSiO_(2)@DOTA-TATE were confirmed with AuNRs@mSiO_(2)@64Cu-DOTA-TATE under micro-positron emission tomography/computed tomography(micro-PET/CT);in the AuNRs@mSiO_(2)@DOTA-TATE with laser group,the tumour surface temperature increased rapidly,with tumour volumes similar to those in the octreotide group and significantly lower than those in other groups.There was no significant difference in mice body weight between the AuNRs@mSiO_(2)@DOTA-TATE with laser group and other groups.No significant inflammatory lesions or cell necrosis was found in the main organs.In summary,we presented a feasible strategy to construct AuNRs@mSiO_(2)@DOTA-TATE with good photothermal conversion efficiency,targetingSSTR2 ability,significant antitumour effects,and good biocompatibility,warranting further explorations of AuNRs@mSiO_(2)@DOTA-TATE for NETs therapy applications.

Histidine decarboxylase and urinary methylimidazoleacetic acid in gastric neuroendocrine cells and tumours

AIM: To study histidine decarboxylase(HDC) expression in normal and neoplastic gastric neuroendocrine cells in relationship to the main histamine metabolite. METHODS: Control tissues from fundus(n = 3) and corpus(n = 3) mucosa of six patients undergoing operations for gastric adenocarcinoma, biopsy and/or gastric surgical specimens from 64 patients with primary gastric neuroendocrine tumours(GNETs), as well as metastases from 22 of these patients, were investigated using conventional immunohistochemistry and double immunofluorescence with commercial antibodies vs vesicular monoamine transporter 2(VMAT-2), HDC and ghrelin. The urinary excretion of the main histamine metabolite methylimidazoleacetic acid(U-Me Im AA) was determined using highperformance liquid chromatography in 27 of the 64 patients.RESULTS: In the gastric mucosa of the control tissues, co-localization studies identified neuroendocrine cells that showed immunoreactivity only to VMAT-2 and others with reactivity only to HDC. A third cellpopulation co-expressed both antigens. There was no co-expression of HDC and ghrelin. Similar results were obtained in the foci of neuroendocrine cell hyperplasia associated with chronic atrophic gastritis type A and also in the tumours. The relative incidence of the three aforementioned markers varied in the tumours that were examined using conventional immunohistochemistry. All of these GNETs revealed both VMAT-2 and HDC immunoreactivity, and their metastases showed an immunohistochemical pattern and frequency similar to that of their primary tumours. In four patients, increased U-Me Im AA excretion was detected, but only two of the patients exhibited related endocrine symptoms. CONCLUSION: Human enterochromaffin-like cells appear to partially co-express VMAT-2 and HDC. Coexpression of VMAT-2 and HDC might be required for increased histamine production in patients with GNETs.

New insights in diagnosis and treatment of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms(GEP-NENs)are rare epithelial neoplasms derived from pluripotent endocrine cells along the gastrointestinal tract and pancreas.GEP-NENs are classified into well-differentiated neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas.Despite overlapping morphological features,GEP-NENs vary in molecular biology,epigenetic,clinical behavior,treatment response,and prognosis features and remain an unmet clinical challenge.In this review,we introduce recent updates on the histopathologic classification,including the tumor grading and staging system,molecular genetics,and systemic evaluation of the diagnosis and treatment of GEP-NENs at different anatomic sites,together with some insights into the diagnosis of challenging and unusual cases.We also discuss the application of novel therapeutic approaches for GEP-NENs,including peptide receptor radionuclide therapy,targeted therapy,and immunotherapy with immune checkpoint inhibitors.These findings will help improve patient care with precise diagnosis and individualized treatment of patients with GEP-NENs.

Gastroenteropancreatic neuroendocrine neoplasms:A clinical snapshot

Our understanding about the epidemiological aspects,pathogenesis,molecular diagnosis,and targeted therapies of neuroendocrine neoplasms(NENs)have drastically advanced in the past decade.Gastroenteropancreatic(GEP)NENs originate from the enteroendocrine cells of the embryonic gut which share common endocrine and neural differentiation factors.Most NENs are welldifferentiated,and slow growing.Specific neuroendocrine biomarkers that are used in the diagnosis of functional NENs include insulin,glucagon,vasoactive intestinal polypeptide,gastrin,somatostatin,adrenocorticotropin,growth hormone releasing hormone,parathyroid hormone-related peptide,serotonin,histamine,and 5-hydroxy indole acetic acid(5-HIAA).Biomarkers such as pancreatic polypeptide,human chorionic gonadotrophin subunits,neurotensin,ghrelin,and calcitonin are used in the diagnosis of non-functional NENs.5-HIAA levels correlate with tumour burden,prognosis and development of carcinoid heart disease and mesenteric fibrosis,however several diseases,medications and edible products can falsely elevate the 5-HIAA levels.Organ-specific transcription factors are useful in the differential diagnosis of metastasis from an unknown primary of well-differentiated NENs.Emerging novel biomarkers include circulating tumour cells,circulating tumour DNA,circulating micro-RNAs,and neuroendocrine neoplasms test(NETest)(simultaneous measurement of 51 neuroendocrine-specific marker genes in the peripheral blood).NETest has high sensitivity(85%-98%)and specificity(93%-97%)for the detection of gastrointestinal NENs,and is useful for monitoring treatment response,recurrence,and prognosis.In terms of management,surgery,radiofrequency ablation,symptom control with medications,chemotherapy and molecular targeted therapies are all considered as options.Surgery is the mainstay of treatment,but depends on factors including age of the individual,location,stage,grade,functional status,and the heredity of the tumour(sporadic vs inherited).Medical management is helpful to alleviate the symptoms,manage inoperable lesions,suppress postoperative tumour growth,and manage recurrences.Several molecular-targeted therapies are considered second line to somatostatin analogues.This review is a clinical update on the pathophysiological aspects,diagnostic algorithm,and management of GEP NENs.

Quality of life in patients with gastroenteropancreatic tumours: A systematic literature review

BACKGROUND Gastroenteropancreatic neuroendocrine tumours(GEP-NETs)are slow-growing cancers that arise from diffuse endocrine cells in the gastrointestinal tract(GINETs)or the pancreas(P-NETs).They are relatively uncommon,accounting for 2%of all gastrointestinal malignancies.The usual treatment options in advanced GEP-NET patients with metastatic disease include chemotherapy,biological therapies,and peptide receptor radionuclide therapy.Understanding the impact of treatment on GEP-NET patients is paramount given the nature of the disease.Health-related quality of life(HRQoL)is increasingly important as a concept reflecting the patients’perspective in conjunction with the disease presentation,severity and treatment.AIM To conduct a systematic literature review to identify literature reporting HRQoL data in patients with GEP-NETs between January 1985 and November 2019.METHODS The PRISMA guiding principles were applied.MEDLINE,Embase and the Cochrane library were searched.Data extracted from the publications included type of study,patient population data(mid-gut/hind-gut/GI-NET/P-NET),sample size,intervention/comparators,HRQoL instruments,average and data spread of overall and sub-scores,and follow-up time for data collection.RESULTS Forty-three publications met the inclusion criteria.The heterogeneous nature of the different study populations was evident;the percentage of female participants ranged between 30%-60%,whilst average age ranged from 53.8 to 67.0 years.Eight studies investigated GI-NET patients only,six studies focused exclusively on P-NET patients and the remaining studies involved both patient populations or did not report the location of the primary tumour.The most commonly used instrument was the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30(n=28)with consistent results across studies;the GI-NET-specific module Quality of Life Questionnaire-GINET21 was used in six of these studies.A number of randomised trials demonstrated no HRQoL changes between active treatment and placebo arms.The Phase III NETTER-1 study provides the best data available for advanced GEP-NET patients;it shows that peptide receptor radionuclide therapy can significantly improve GEP-NET patients’HRQoL.CONCLUSION HRQoL instruments offer a means to monitor patients’general disease condition,disease progression and their physical and mental well-being.Instruments including the commonly used European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30 and GINET21 lack,however,validation and a defined minimal clinical important difference specifically for GINET and P-NET patients.

Tunneled biopsy is an underutilised,simple,safe and efficient method for tissue acquisition from subepithelial tumours

BACKGROUND Tissue acquisition from subepithelial lesions is often attempted by endoscopic ultrasound(EUS)-sampling as conventional endoscopic biopsy usually fails to reach deeper layers of the gastrointestinal wall.AIM To investigate the utilisation,safety and diagnostic yield of an intensified“biteon-bite”tunnel biopsy technique.METHODS In this retrospective cohort study,all patients presenting with subepithelial masses in the upper gastrointestinal tract from March 2013 to July 2019 were included.Data were analysed for size and location of the subepithelial mass,use of intensified tunnel biopsy protocol(more than 10 double bite-on-bite biopsies)or superficial conventional biopsies,histology and imaging results,occurrence of readmission and adverse events after endoscopy.RESULTS Two hundred and twenty-nine patients with subepithelial lesions were included.Superficial conventional biopsies were taken in 117 patients and were diagnostic only in one lipoma(0.9%).Tunnel biopsies taken in 112/229(48.9%)patients were significantly more likely to provide histological diagnosis(53.6%;P<0.001).For lesions≥10mm the diagnostic yield of tunnel biopsies further increased to 41/67(61.2%).No immediate or delayed complications were reported.Only 8 of the 51 endoscopists(15.7%)regularly attempted tunnel biopsies.CONCLUSION Tunnel biopsy is a simple,safe and efficient but underutilised diagnostic modality for tissue acquisition in subepithelial masses.It should be routinely attempted at the initial endoscopy.

Octreotide acetate long-acting release in treatment of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumours are uncommon neoplasms of the pancreas, accounting for around 2% of all primary pancreatic tumors. This specific group of tumours includes insulinoma, gastrinoma, glucagonoma, VIPoma, somatostatinoma and others. They may cause a clinical syndrome due to hormone overproduction. These tumours tend to be less aggressive than pancreatic adenocarcinoma, however, more than 50% of them have metastasized to the liver at the time of diagnosis. Under this circumstance, surgery is impossible to resect all metastases. Thus other various medical measures have been explored in the treatment of these tumors.