Multifocality in Small Bowel Neuroendocrine Tumors

The utility of fluorescence imaging in detecting primary and metastatic small bowel carcinoid tumors

BACKGROUND

Our aim was to investigate utility of indocyanine green (ICG) and autofluorescence (AF) imaging in detection of small bowel primary and metastatic carcinoids.

METHODS

Using Institutional Review Board approval, ICG and AF imaging of small bowel carcinoids was performed. Imaging findings were prospectively recorded in operating room and compared with conventional imaging, surgical exploration and pathologic findings.

RESULTS

There were 16 patients with 23 primary small bowel tumors, 27 mesenteric lymph nodes, 36 liver metastases and 2 peritoneal nodules. Carcinoid tumors exhibited brighter AF signals compared to background. AF imaging was superior to both DOTATATE PET and surgeon inspection/palpation in demonstrating small bowel primaries. Utility for metastatic lymph nodes and peritoneal metastases was limited. Superficial liver metastases exhibited brighter fluorescence compared to background on both ICG and AF imaging.

CONCLUSIONS

This is the largest study assessing utility of near-infrared fluorescence imaging in detection of small bowel carcinoids. Our results show promise in the utilization fluorescence imaging to detect occult primary tumors and superficial liver metastases.

The Molecular Biology of Midgut Neuroendocrine Neoplasms

Midgut neuroendocrine neoplasms (NENs) are one of the most common subtypes of NEN, and their incidence is rising globally. Despite being the most frequently diagnosed malignancy of the small intestine, little is known about their underlying molecular biology. Their unusually low mutational burden compared to other solid tumors and the unexplained occurrence of multifocal tumors makes the molecular biology of midgut NENs a particularly fascinating field of research. This review provides an overview of recent advances in the understanding of the interplay of the genetic, epigenetic, and transcriptomic landscape in the development of midgut NENs, a topic that is critical to understanding their biology and improving treatment options and outcomes for patients.

Surgery for advanced neuroendocrine tumours of the small bowel: recommendations based on a consensus meeting of the European Society of Endocrine Surgeons (ESES)

BACKGROUND

Small bowel neuroendocrine tumours often present with locally advanced or metastatic disease. The aim of this paper is to provide evidence-based recommendations regarding (controversial) topics in the surgical management of advanced small bowel neuroendocrine tumours.

METHODS

A working group of experts was formed by the European Society of Endocrine Surgeons. The group addressed 11 clinically relevant questions regarding surgery for advanced disease, including the benefit of primary tumour resection, the role of cytoreduction, the extent of lymph node clearance, and the management of an unknown primary tumour. A systematic literature search was performed in MEDLINE to identify papers addressing the research questions. Final recommendations were presented and voted upon by European Society of Endocrine Surgeons members at the European Society of Endocrine Surgeons Conference in Mainz in 2023.

RESULTS

The literature review yielded 1223 papers, of which 84 were included. There were no randomized controlled trials to address any of the research questions and therefore conclusions were based on the available case series, cohort studies, and systematic reviews/meta-analyses of the available non-randomized studies. The proposed recommendations were scored by 38-51 members and rated 'strongly agree' or 'agree' by 64-96% of participants.

CONCLUSION

This paper provides recommendations based on the best available evidence and expert opinion on the surgical management of locally advanced and metastatic small bowel neuroendocrine tumours.

Diagnosis and staging of small intestinal neuroendocrine tumors with CT enterography and PET with Gallium-68: preoperative risk stratification protocol

PURPOSE

Pre-operative diagnosis and staging of small intestine neuroendocrine tumors (SI-NETs) remain sub-optimal, with open palpation during surgery still considered the gold standard. This limits a standardized implementation of minimally invasive surgery (MIS). The aim of this single-center retrospective study was to assess a tailored diagnostic work-up to identify candidates at low risk of undetected disease who may benefit from MIS.

METHODS

Patients diagnosed with SI-NETs between 2013 and 2022 who underwent contrast-enhanced computed tomography enterography (CTE) and Ga68-DOTATOC-positron emission tomography-CT (68 Ga DOTATATE PET/CT) preoperatively and subsequently underwent open surgical resection were included. Imaging studies were reassessed by two radiologists. Combined use of CTE and 68 Ga DOTATATE PET/CT in determining primary lesion disease burden (number of lesions) and LN disease stage (distal and proximal relative to superior mesenteric vessels) was assessed, using surgical reports and pathology as gold standard.

RESULTS

Overall, 56 patients were included. Sensitivity of CTE and 68 Ga DOTATATE PET/CT for at least one primary SI-NET was 100% and 94%, respectively. In the presence of concordance between studies, combined use of CTE and 68 Ga DOTATATE PET/CT for detection of single primary tumors improved specificity to 89% (n = 25/28) with a positive predictive value of 87.5% (n = 21/24). Distal LN disease was identified in 89.2% of cases (n = 33/37). The association of single lesion and distal LN disease was found pre-operatively in 32% of patients (n = 18).

CONCLUSION

Combined use of CTE and 68 Ga DOTATATE PET/CT enables identifying low-risk surgical candidates (single SI-NET lesions with distal LN disease).

Performance of capsule endoscopy for the detection of small intestinal neuroendocrine tumors in familial carcinoid: a prospective single-site study

BACKGROUND AND AIMS

Small-bowel neuroendocrine tumors (NETs) are slow growing, clinically silent tumors whose prognosis depends on disease stage. Members of kindreds with a familial form of small intestinal NETs (SI-NETs) represent a high-risk population for whom early detection improves disease outcome. Our aim was to determine the utility of small-bowel capsule endoscopy (SB-CE) for screening high-risk asymptomatic relatives from kindreds with familial carcinoid.

METHODS

One hundred seventy-four asymptomatic subjects with a family history (≥2 family members) of SI-NETs were screened under Protocol NCT00646022, Natural History of Familial Carcinoid Tumor at the National Institutes of Health. All patients were imaged with SB-CE and 18fluoro-dihydroxphenylalanine (18F-DOPA) positron emission tomography (PET)/CT, and results were independently analyzed. Patients with a positive imaging study underwent surgical exploration.

RESULTS

Thirty-five of 174 asymptomatic subjects screened for SI-NETs were positive on either SB-CE or 18F-DOPA PET. Thirty-two of 35 patients with a positive study were confirmed at surgery. SB-CE was positive in 28 of 32 patients with confirmed tumors for a per-patient sensitivity of 87.5%. SB-CE had a specificity of 97.3% and a negative predictive value of 96.5%. The average tumor number and size were 7.7 and 5.0 mm, respectively, and 81.2% of patients had multiple tumors. 18F-DOPA PET/CT had a similar sensitivity of 84% versus surgery.

CONCLUSIONS

SB-CE is a sensitive and specific method comparable with 18F-DOPA PET/CT for screening high-risk patients with familial SI-NET. (Clinical trial registration number: NCT00646022.).

The Role of Capsule Endoscopy in the Diagnosis and Management of Small Bowel Tumors: A Narrative Review

Small bowel tumors (SBT) are relatively rare, but have had a steadily increasing incidence in the last few decades. Small bowel capsule endoscopy (SBCE) and device-assisted enteroscopy are the main endoscopic techniques for the study of the small bowel, the latter additionally providing sampling and therapeutic options, and hence acting complementary to SBCE in the diagnostic work-up. Although a single diagnostic modality is often insufficient in the setting of SBTs, SBCE is a fundamental tool to drive further management towards a definitive diagnosis. The aim of this paper is to provide a concise narrative review of the role of SBCE in the diagnosis and management of SBTs.

Small Bowel Neuroendocrine Neoplasms-A Review

ABSTRACT

Neuroendocrine neoplasms (NENs) are rapidly evolving small bowel tumors, and the patients are asymptomatic at the initial stages. Metastases are commonly observed at the time of presentation and diagnosis. This review addresses the small bowel NEN (SB-NEN) and its molecular, histological, and imaging features, which aid diagnosis and therapy guidance. Somatic cell number alterations and epigenetic mutations are studied to be responsible for sporadic and familial SB-NEN. The review also describes the grading of SB-NEN in addition to rare histological findings such as mixed neuroendocrine-non-NENs. Anatomic and nuclear imaging with conventional computed tomography, magnetic resonance imaging, computed tomographic enterography, and positron emission tomography are adopted in clinical practice for diagnosing, staging, and follow-up of NEN. Along with the characteristic imaging features of SB-NEN, the therapeutic aspects of imaging, such as peptide receptor radionuclide therapy, are discussed in this review.

Accuracy of DOTATATE PET imaging in the preoperative planning of small bowel neuroendocrine tumor resection

BACKGROUND AND OBJECTIVES

We assessed the accuracy of preoperative gallium-68 DOTA-Tyr3-octreotate (DOTATATE) positron emission tomography (PET) imaging in estimating multifocality and nodal metastases of small bowel neuroendocrine tumors (sbNETs).

METHODS

A multicenter analysis was performed on patients with sbNETs who underwent preoperative DOTATATE PET imaging and surgical resection, with manual palpation of the entire length of the small bowel, between January 2016 and August 2022. Preoperative imaging reports and blinded secondary imaging reviews were compared to the final postoperative pathology reports. Descriptive statistics were applied.

RESULTS

One-hundred and four patients met inclusion criteria. Pathology showed 53 (51%) patients had multifocal sbNETs and 96 (92%) had nodal metastases. The original preoperative DOTATATE PET imaging identified multifocal sbNET in 28 (27%) patients and lymph node (LN) metastases in 80 (77%) patients. Based on original radiology reports, sensitivity for multifocal sbNET identification was 45%, specificity was 92%, positive predictive value (PPV) was 86%, and negative predictive value (NPV) was 62%. For the identification of LN metastases, sensitivity was 82%, specificity was 88%, PPV was 99%, and NPV was 29%.

CONCLUSIONS

Although DOTATATE PET imaging is specific and relatively accurate, sensitivity and NPV are insufficient to guide surgical planning. Preoperative use should not replace open palpation to identify additional synchronous lesions or to omit regional lymphadenectomy.

Management of Small Bowel Neuroendocrine Tumours: 10 Years' Experience at a Tertiary Referral Centre

BACKGROUND

Neuroendocrine tumours (NET) arising from the small bowel are clinically challenging and are often diagnosed at advanced stages. Disease control with surgery alone can be demanding. Multimodal treatment concepts integrating surgery and non-surgical modalities could be of benefit.

METHOD

Retrospective review of consecutive adult patients with SB NET treated at Imperial College Healthcare NHS Trust between 1 January 2010 and 31 December 2019. Data regarding clinicopathological characteristics, treatments, and disease trajectory were extracted and summarised. Overall and progression/recurrence-free survival were estimated at 5 and 10 years.

RESULTS

154 patients were identified, with a median age of 64 years (range 33-87); 135/154 (87.7%) had stage III/IV disease at diagnosis. Surgery was used in 125 individuals (81.2%), typically with either segmental small bowel resection (60.8%) or right hemicolectomy (33.6%) and mesenteric lymphadenectomy for the primary tumour. Systemic and/or liver-directed therapies were used in 126 (81.8%); 60 (47.6%) had more than one line of non-surgical treatment. Median follow-up was 67.2 months (range 3.1-310.4); overall survival at 5 and 10 years was 91.0% (95% CI: 84.9-94.7%) and 82.5% (95% CI: 72.9-88.9%), respectively. Imaging-based median progression-free survival was 42.7 months (95% CI: 24.7 to 72.4); 5-year progression-free survival was 63.4% (95% CI: 55.0-70.6%); 10-year progression-free survival was 18.7% (95% CI: 12.4-26.1). Nineteen patients (12.3%) reached 10 years follow-up without disease recurrence and therefore were considered cured.

CONCLUSIONS

Most patients with SB NET present in a metastasised stage. Multimodal treatment concepts may be associated with excellent clinical outcomes. Future work should explore optimal approaches to treatment sequencing and patient selection.

Imaging of Small-Bowel Neuroendocrine Neoplasms: AJR Expert Panel Narrative Review

Neuroendocrine neoplasms (NENs) of the small bowel are typically slow-growing lesions that remain asymptomatic until reaching an advanced stage. Imaging modalities for lesion detection, staging, and follow-up in patients with known or suspected NEN include CT enterography, MR enterography, and PET/CT using a somatostatin receptor analog. FDG PET/CT may have a role in the evaluation of poorly differentiated NENs. Liver MRI, ideally with a hepatocyte-specific contrast agent, should be used in the evaluation of hepatic metastases. Imaging informs decisions regarding both surgical approaches and systematic therapy (specifically, peptide receptor radionuclide therapy). This AJR Expert Panel Narrative Review describes the multimodality imaging features of small-bowel NENs; explores the optimal imaging modalities for their diagnosis, staging, and follow-up; and discusses how imaging may be used to guide therapy.

Role of Advanced Gastrointestinal Endoscopy in the Comprehensive Management of Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs), also called neuroendocrine tumors (NETs), are relatively uncommon, heterogenous tumors primarily originating in the gastrointestinal tract. With the improvement in technology and increasing use of cross-sectional imaging and endoscopy, they are being discovered with increasing frequency. Although traditionally considered indolent tumors with good prognoses, some NENs exhibit aggressive behavior. Timely diagnosis, risk stratification, and management can often be a challenge. In general, small NENs without local invasion or lymphovascular involvement can often be managed using minimally invasive advanced endoscopic techniques, while larger lesions and those with evidence of lymphovascular invasion require surgery, systemic therapy, or a combination thereof. Ideal management requires a comprehensive and accurate understanding of the stage and grade of the tumor. With the recent advancements, a therapeutic advanced endoscopist can play a pivotal role in diagnosing, staging, and managing this rare condition. High-definition white light imaging and digital image enhancing technologies like narrow band imaging (NBI) in the newer endoscopes have improved the diagnostic accuracy of traditional endoscopy. The refinement of endoscopic ultrasound (EUS) over the past decade has revolutionized the role of endoscopy in diagnosing and managing various pathologies, including NENs. In addition to EUS-directed diagnostic biopsies, it also offers the ability to precisely assess the depth of invasion and lymphovascular involvement and thus stage NENs accurately. EUS-directed locoregional ablative therapies are increasingly recognized as highly effective, minimally invasive treatment modalities for NENs, particularly pancreatic NENs. Advanced endoscopic resection techniques like endoscopic submucosal dissection (ESD), endoscopic submucosal resection (EMR), and endoscopic full-thickness resection (EFTR) have been increasingly used over the past decade with excellent results in achieving curative resection of various early-stage gastrointestinal luminal lesions including NENs. In this article, we aim to delineate NENs of the different segments of the gastrointestinal (GI) tract (esophagus, gastric, pancreatic, and small and large intestine) and their management with emphasis on the endoscopic management of these tumors.

Appendiceal Neuroendocrine Neoplasms: A Comprehensive Review

ABSTRACT

Appendiceal neuroendocrine neoplasm (NEN) is the most common adult appendiceal malignant tumor, constituting 16% of gastrointestinal NENs. They are versatile tumors with varying morphology, immunohistochemistry, secretory properties, and cancer genomics. They are slow growing and clinically silent, to begin with, or present with features of nonspecific vague abdominal pain. Most acute presentations are attributed clinically to appendicitis, with most cases detected incidentally on pathology after an appendectomy. Approximately 40% of them present clinically with features of hormonal excess, which is likened to the functional secretory nature of their parent cell of origin. The symptoms of carcinoid syndrome render their presence clinically evident. However, slow growing and symptomatically silent in its initial stages, high-grade neuroendocrine tumors and neuroendocrine carcinomas of the appendix are aggressive and usually have hepatic and lymph node metastasis at presentation. This review article focuses on imaging characteristics, World Health Organization histopathological classification and grading, American Joint Committee on Cancer/Union or International Cancer Control, European Neuroendocrine Tumor Society staging, European Neuroendocrine Tumor Society standardized guidelines for reporting, data interpretation, early-stage management protocols, and advanced-stage appendiceal NENs. Guidelines are also set for the follow-up and reassessment. The role of targeted radiotherapy, chemotherapy, and high-dose somatostatin analogs in treating advanced disease are discussed, along with types of ablative therapies and liver transplantation for tumor recurrence. The search for newer location-specific biomarkers in NEN is also summarized. Regarding the varying aggressiveness of the tumor, there is a scope for research in the field, with plenty of data yet to be discovered.

Updates in the diagnosis and management of small-bowel tumors

Small-bowel tumors represent a rare entity comprising 0.6% of all new cancer cases in the US, and only 3% of all gastrointestinal neoplasms. They are a heterogenous group of neoplasms comprising of about forty different histological subtypes with the most common being adenocarcinoma, neuroendocrine tumors, stromal tumors and lymphomas. Their incidence has been reportedly increasing over recent years, partly owing to the advances and developments in the diagnostic modalities. Small-bowel capsule endoscopy, device assisted enteroscopy and dedicated small-bowel cross-sectional imaging are complimentary tools, supplementing each other in the diagnostic process. Therapeutic management of small-bowel tumors largely depends on the histological type and staging at diagnosis. The aim of the present review article is to discuss relevant advances in the diagnosis and management of small-bowel tumors.

[Use of Device-Assisted Enteroscopy in Small Bowel Disease: An Expert Consensus Statement by the Korean Association for the Study of Intestinal Diseases]

The introduction of device-assisted enteroscopy (DAE) in the beginning of the 21st century has revolutionized the diagnosis and treatment of diseases of the small intestine. In contrast to capsule endoscopy, the other main diagnostic modality of small bowel diseases, DAE has the unique advantages of allowing the observation of the region of interest in detail and enabling tissue acquisition and therapeutic intervention. As DAE becomes an essential procedure in daily clinical practice, there is an increasing need for correct guidelines on when and how it is to be performed and what technical factors should be taken into consideration. In response to these needs, the Korean Association for the Study of Intestinal Diseases has developed an expert consensus statement on the performance of DAE by reviewing current evidence. This expert consensus statement particularly focuses on the indications, choice of insertion route, therapeutic intervention, complications, and relevant technical points.

Long-term organoid culture of a small intestinal neuroendocrine tumor

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and highly heterogeneous neoplasms whose incidence has markedly increased over the last decades. A grading system based on the tumor cells' proliferation index predicts high-risk for G3 NETs. However, low-to-intermediate grade (G1/G2) NETs have an unpredictable clinical course that varies from indolent to highly malignant. Cultures of human cancer cells enable to perform functional perturbation analyses that are instrumental to enhance our understanding of cancer biology. To date, no tractable and reliable long-term culture of G1/G2 NET has been reported to permit disease modeling and pharmacological screens. Here, we report of the first long-term culture of a G2 metastatic small intestinal NET that preserves the main genetic drivers of the tumor and retains expression patterns of the endocrine cell lineage. Replicating the tissue, this long-term culture showed a low proliferation index, and yet it could be propagated continuously without dramatic changes in the karyotype. The model was readily available for pharmacological screens using targeted agents and as expected, showed low tumorigenic capacity in vivo. Overall, this is the first long-term culture of NETs to faithfully recapitulate many aspects of the original neuroendocrine tumor.

Small-bowel capsule endoscopy and device-assisted enteroscopy for diagnosis and treatment of small-bowel disorders: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2022

MR1: ESGE recommends small-bowel capsule endoscopy as the first-line examination, before consideration of other endoscopic and radiological diagnostic tests for suspected small-bowel bleeding, given the excellent safety profile of capsule endoscopy, its patient tolerability, and its potential to visualize the entire small-bowel mucosa.Strong recommendation, moderate quality evidence. MR2: ESGE recommends small-bowel capsule endoscopy in patients with overt suspected small-bowel bleeding as soon as possible after the bleeding episode, ideally within 48 hours, to maximize the diagnostic and subsequent therapeutic yield.Strong recommendation, high quality evidence. MR3: ESGE does not recommend routine second-look endoscopy prior to small-bowel capsule endoscopy in patients with suspected small-bowel bleeding or iron-deficiency anemia.Strong recommendation, low quality evidence. MR4: ESGE recommends conservative management in those patients with suspected small-bowel bleeding and high quality negative small-bowel capsule endoscopy.Strong recommendation, moderate quality evidence. MR5: ESGE recommends device-assisted enteroscopy to confirm and possibly treat lesions identified by small-bowel capsule endoscopy.Strong recommendation, high quality evidence. MR6: ESGE recommends the performance of small-bowel capsule endoscopy as a first-line examination in patients with iron-deficiency anemia when small bowel evaluation is indicated.Strong recommendation, high quality evidence. MR7: ESGE recommends small-bowel capsule endoscopy in patients with suspected Crohn's disease and negative ileocolonoscopy findings as the initial diagnostic modality for investigating the small bowel, in the absence of obstructive symptoms or known bowel stenosis.Strong recommendation, high quality evidence. MR8: ESGE recommends, in patients with unremarkable or nondiagnostic findings from dedicated small-bowel cross-sectional imaging, small-bowel capsule endoscopy as a subsequent investigation if deemed likely to influence patient management.Strong recommendation, low quality evidence. MR9: ESGE recommends, in patients with established Crohn's disease, the use of a patency capsule before small-bowel capsule endoscopy to decrease the capsule retention rate.Strong recommendation, moderate quality evidence. MR10: ESGE recommends device-assisted enteroscopy (DAE) as an alternative to surgery for foreign bodies retained in the small bowel requiring retrieval in patients without acute intestinal obstruction.Strong recommendation, moderate quality evidence. MR11: ESGE recommends DAE-endoscopic retrograde cholangiopancreatography (DAE-ERCP) as a first-line endoscopic approach to treat pancreaticobiliary diseases in patients with surgically altered anatomy (except for Billroth II patients).Strong recommendation, moderate quality evidence.

Use of device-assisted enteroscopy in small bowel disease: an expert consensus statement by the Korean Association for the Study of Intestinal Diseases

The introduction of device-assisted enteroscopy (DAE) in the beginning of 21st century has revolutionized the diagnosis and treatment of diseases of the small intestine. In contrast to capsule endoscopy, the other main diagnostic modality of the small bowel diseases, DAE has the unique advantages of observing the region of interest in detail and enabling tissue acquisition and therapeutic intervention. As DAE becomes an essential procedure in daily clinical practice, there is an increasing need for correct guidelines on when and how to perform it and what technical factors should be considered. In response to these needs, the Korean Association for the Study of Intestinal Diseases developed an expert consensus statement on the performance of DAE by reviewing the current evidence. This expert consensus statement particularly focuses on the indications, choice of insertion route, therapeutic intervention, complications, and relevant technical points.

Diagnostic work-up and advancement in the diagnosis of gastroenteropancreatic neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms ranging from well-differentiated, slowly growing tumors to poorly differentiated carcinomas. These tumors are generally characterized by indolent course and quite often absence of specific symptoms, thus eluding diagnosis until at an advanced stage. This underscores the importance of establishing a prompt and accurate diagnosis. The gold-standard remains histopathology. This should contain neuroendocrine-specific markers, such as chromogranin A; and also, an estimate of the proliferation by Ki-67 (or MIB-1), which is pivotal for treatment selection and prognostication. Initial work-up involves assessment of serum Chromogranin A and in selected patients gut peptide hormones. More recently, the measurement of multiple NEN-related transcripts, or the detection of circulating tumor cells enhanced our current diagnostic armamentarium and appears to supersede historical serum markers, such as Chromogranin A. Standard imaging procedures include cross-sectional imaging, either computed tomography or magnetic resonance, and are combined with somatostatin receptor scintigraphy. In particular, the advent of ¹¹¹In-DTPA-octreotide and more recently PET/CT and ⁶⁸Ga-DOTA-Octreotate scans revolutionized the diagnostic landscape of NENs. Likewise, FDG PET represents an invaluable asset in the management of high-grade neuroendocrine carcinomas. Lastly, endoscopy, either conventional, or more advanced modalities such as endoscopic ultrasound, capsule endoscopy and enteroscopy, are essential for the diagnosis and staging of gastroenteropancreatic neuroendocrine neoplasms and are routinely integrated in clinical practice. The complexity and variability of NENs necessitate the deep understanding of the current diagnostic strategies, which in turn assists in offering optimal patient-tailored treatment. The current review article presents the diagnostic work-up of GEP-NENs and all the recent advances in the field.

High-Contrast Detection of Somatostatin Receptor Subtype-2 for Fluorescence-Guided Surgery

Dye design can influence the ability of fluorescently labeled imaging agents to generate tumor contrast and has become an area of significant interest in the field of fluorescence-guided surgery (FGS). Here, we show that the charge-balanced near-infrared fluorescent (NIRF) dye FNIR-Tag enhances the imaging properties of a fluorescently labeled somatostatin analogue. In vitro studies showed that the optimized fluorescent conjugate MMC(FNIR-Tag)-TOC bound primarily via somatostatin receptor subtype-2 (SSTR2), whereas its negatively charged counterpart with IRDye 800CW had higher off-target binding. NIRF imaging in cell line- and patient-derived xenograft models revealed markedly higher tumor contrast with MMC(FNIR-Tag)-TOC, which was attributed to increased tumor specificity. Ex vivo staining of surgical biospecimens from primary and metastatic tumors, as well as involved lymph nodes, demonstrated binding to human tumors. Finally, in an orthotopic tumor model, a simulated clinical workflow highlighted our unique ability to use standard preoperative nuclear imaging for selecting patients likely to benefit from SSTR2-targeted FGS. Our findings demonstrate the translational potential of MMC(FNIR-Tag)-TOC for intraoperative imaging and suggest broad utility for using FNIR-Tag in fluorescent probe development.

Diagnosis and management of small bowel neuroendocrine tumors: A state-of-the-art

This review provides an update on the epidemiology, pathophysiology, symptoms, diagnosis and treatment of neuroendocrine neoplasms (NENs) of the small bowel (SB). These NENs are defined as a group of neoplasms deriving from neuroendocrine cells. NENs are currently the most common primary tumors of the SB, mainly involving the ileum, making the SB the most frequently affected part of the gastrointestinal tract. SB NENs by definition are located between the ligament of Treitz and the ileocecal valve. They are characterized by small size and induce an extensive fibrotic reaction in the small intestine including the mesentery, resulting in narrowing or twisting of the intestine. Clinical manifestations of bowel functionality are related to the precise location of the primary tumor. The majority of them are non-functional NENs and generally asymptomatic; in an advanced stage, NENs present symptoms of mass effect by non-specific abdominal pain or carcinoid syndrome which appears in patients with liver metastasis (around 10%). The main manifestations of the carcinoid syndrome are facial flushing (94%), diarrhea (78%), abdominal cramps (50%), heart valve disease (50%), telangiectasia (25%), wheezing (15%) and edema (19%). Diagnosis is made by imaging or biochemical tests, and the order of request will depend on the initial diagnostic hypothesis, while confirmation will always be histological. All patients with a localized SB NEN with or without near metastasis in the mesentery are recommended for curative resection. Locoregional and distant spread may be susceptible to several therapeutic strategies, such as chemotherapy, somatostatin analogs and palliative resection.

Frequency and Prognostic Significance of Intertumoural Heterogeneity in Multifocal Jejunoileal Neuroendocrine Tumours

Background: A recent study found that multifocal jejunoileal neuroendocrine tumors (SI-NETs) are genetically unrelated synchronous neoplasms. So far, it is unclear if this finding of synchronous independent neoplasms is mirrored by heterogeneity of key morphological parameters of SI-NETs and how it affects patient survival. Methods: We separately assessed WHO grade (based on the Ki-67 index), expression of basal diagnostic markers (synaptophysin/chromogranin A/CDX2/serotonin), SSTR2a, and the contexture of the immunogenic microenvironment in 146 separate tumors from 28 patients with multifocal SI-NETs and correlated the results with clinicopathological factors and survival. Results: Synaptophysin and chromogranin A were strongly expressed in all tumors. WHO grade was concordant within all multifocal lesions in more than 80% of cases and the highest grade was usually found in the most advanced primary. Intertumoral expression of serotonin, SSTR2, and CDX2 was discrepant in 32%, 43%, and 50% of all patients, respectively. Neither heterogeneity of any of the aforementioned markers nor multifocality itself had any impact on patient survival (p = n.s.). Discussion: Multifocal SI-NET show considerable variability in some of the central diagnostic parameters. However, neither intertumoral heterogeneity of those parameters nor multifocality itself had any impact on patient survival, showing that extensive testing of all multifocal lesions is not necessarily required.

Whole genome sequencing reveals the independent clonal origin of multifocal ileal neuroendocrine tumors

Background

Small intestinal neuroendocrine tumors (SI-NETs) are the most common neoplasms of the small bowel. The majority of tumors are located in the distal ileum with a high incidence of multiple synchronous primary tumors. Even though up to 50% of SI-NET patients are diagnosed with multifocal disease, the mechanisms underlying multiple synchronous lesions remain elusive.

Methods

We performed whole genome sequencing of 75 de-identified synchronous primary tumors, 15 metastases, and corresponding normal samples from 13 patients with multifocal ileal NETs to identify recurrent somatic genomic alterations, frequently affected signaling pathways, and shared mutation signatures among multifocal SI-NETs. Additionally, we carried out chromosome mapping of the most recurrent copy-number alterations identified to determine which parental allele had been affected in each tumor and assessed the clonal relationships of the tumors within each patient.

Results

Absence of shared somatic variation between the synchronous primary tumors within each patient was observed, indicating that these tumors develop independently. Although recurrent copy-number alterations were identified, additional chromosome mapping revealed that tumors from the same patient can gain or lose different parental alleles. In addition to the previously reported CDKN1B loss-of-function mutations, we observed potential loss-of-function gene alterations in TNRC6B, a candidate tumor suppressor gene in a small subset of ileal NETs. Furthermore, we show that multiple metastases in the same patient can originate from either one or several primary tumors.

Conclusions

Our study demonstrates major genomic diversity among multifocal ileal NETs, highlighting the need to identify and remove all primary tumors, which have the potential to metastasize, and the need for optimized targeted treatments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01083-1.

Independent somatic evolution underlies clustered neuroendocrine tumors in the human small intestine

Small intestine neuroendocrine tumor (SI-NET), the most common cancer of the small bowel, often displays a curious multifocal phenotype with several tumors clustered together in a limited intestinal segment. SI-NET also shows an unusual absence of driver mutations explaining tumor initiation and metastatic spread. The evolutionary trajectories that underlie multifocal SI-NET lesions could provide insight into the underlying tumor biology, but this question remains unresolved. Here, we determine the complete genome sequences of 61 tumors and metastases from 11 patients with multifocal SI-NET, allowing for elucidation of phylogenetic relationships between tumors within single patients. Intra-individual comparisons revealed a lack of shared somatic single-nucleotide variants among the sampled intestinal lesions, supporting an independent clonal origin. Furthermore, in three of the patients, two independent tumors had metastasized. We conclude that primary multifocal SI-NETs generally arise from clonally independent cells, suggesting a contribution from a cancer-priming local factor.

Principles of Surgical Management of Small Intestinal NET

INTRODUCTION

Small-intestinal neuroendocrine tumors (siNETs) account for 25% of gastroenteropancreatic NETs. Multiple siNETs appear to develop in a limited segment of the small bowel (SB), 89% of them being located in the ileum, most often within 100 cm of the ileocecal valve (ICV). According to the European Neuroendocrine Tumor Society (ENETS) and the American Joint Committee on Cancer (AJCC), all localized siNETs should be considered for radical surgical resection with adequate lymphadenectomy irrespective of the absence of lymphadenopathy or mesenteric involvement. Surgical management of siNETs: The preoperative workout should include a precise evaluation of past medical and surgical history, focusing on the symptoms of carcinoid syndrome (flush, diarrhea, and cardiac failure). Morphological evaluation should include a CT scan including a thin-slice arterial CT, a PET/CT with 68 Ga, and a hepatic MRI in cases of suspected metastasis. Levels of 24 h urinary 5-hydroxyindoleacetic acid are needed. Regarding surgery, the limiting component is the number of free jejunal branches allowing a resection without risk of short small bowel syndrome. The laparoscopic approach has been poorly studied, and open laparotomy remains the gold standard to explore the abdominal cavity and entirely palpate the small bowel through bidigital palpation and compression. An extensive lymphadenectomy is required. A prophylactic cholecystectomy should be performed. In case of emergency surgery, current recommendations are not definitive. However, there is expert agreement that it is not reasonable to initiate resection of the mesenteric mass without comprehensive workup and mapping.

CONCLUSION

The surgery of siNETs is in constant evolution. The challenge lies in the ability to propose a resection without imposing short small bowel syndrome on the patients. The oncological benefits supported in the literature led to recent changes in the recommendations of academic societies. The next steps remain the dissemination of reproducible quality criteria to perform these procedures.

Genetic Drivers of Ileal Neuroendocrine Tumors

Simple Summary

Although ileal neuroendocrine tumors are the most common tumors of the small intestine, they are not well-defined at the genetic level. Unlike most cancers, they have an unusually low number of mutations, and also lack recurrently mutated genes. Moreover ileal NETs have been difficult to study in the laboratory because there were no animal models and because cell lines were generally unavailable. But recent advances, including the first ileal NET mouse model as well as methods for culturing patient tumor samples, have been described and have already helped to identify IGF2 and CDK4 as two of the genetic drivers for this tumor type. These advances may help in the development of new treatments for patients.

Abstract

The genetic causes of ileal neuroendocrine tumors (ileal NETs, or I-NETs) have been a mystery. For most types of tumors, key genes were revealed by large scale genomic sequencing that demonstrated recurrent mutations of specific oncogenes or tumor suppressors. In contrast, genomic sequencing of ileal NETs demonstrated a distinct lack of recurrently mutated genes, suggesting that the mechanisms that drive the formation of I-NETs may be quite different than the cell-intrinsic mutations that drive the formation of other tumor types. However, recent mouse studies have identified the IGF2 and RB1 pathways in the formation of ileal NETs, which is supported by the subsequent analysis of patient samples. Thus, ileal NETs no longer appear to be a cancer without genetic causes.

Multifocality is not associated with worse survival in sporadic pancreatic neuroendocrine tumors

BACKGROUND AND OBJECTIVES

Pancreatic neuroendocrine tumors (pNETs) in patients with hereditary cancer syndromes are typically multifocal. In contrast, sporadic pNETs are usually unifocal and the incidence of multifocal sporadic pNETs is unknown. The primary aim of this study was to investigate the incidence of multifocality in sporadic pNETs and any associated effect on recurrence risk and survival.

METHODS

Patients who underwent resection of pNETs at Mayo Clinic from 2000 to 2019 were identified and clinical data were obtained from medical records. Syndromic disease was defined as pNETs arising in the setting of a hereditary cancer syndrome. Statistical comparisons were made using χ² , Fisher's exact, and Kruskal-Wallis tests and survival was assessed using the Kaplan-Meier method.

RESULTS

Six hundred and sixty-one patients with sporadic pNETs and fifty-nine with syndromic pNETs were identified. Multifocal disease was present in 4.8% of sporadic patients and 84.7% of syndromic patients (p < .001). Within patients with sporadic pNETs, clinicopathologic features and recurrence-free and overall survival were similar between patients with unifocal and multifocal disease.

CONCLUSIONS

Multifocal sporadic pNETs are rare and multifocality is not associated with worse survival or increased recurrence risk. Patients with multifocal sporadic pNETs can likely be safely managed with a combination of resection and observation as indicated for each tumor.

Small bowel enteroscopy - A joint clinical guideline by the Spanish and Portuguese small-bowel study groups

The present evidence-based guidelines are focused on the use of device-assisted enteroscopy in the management of small-bowel diseases. A panel of experts selected by the Spanish and Portuguese small-bowel study groups reviewed the available evidence focusing on the main indications of this technique, its role in the management algorithm of each indication, and its diagnostic and therapeutic yield. A set of recommendations was issued accordingly.

Multifocal Small Bowel Neuroendocrine Tumours

In contemporary surgical series, the incidence of multifocal tumours (MFT) in small bowel neuroendrocrine tumours (SBNET) is as high as 50%. Familial forms of SBNET appear to have an even higher rate of MFTs in the range of 80%. Multifocal disease poses several challenges and questions for the operating surgeon, including the cause of the disease whether it is local metastases or a genetic field defect, the extent of the resection, and the prognosis. The etiology of these multiple tumours appears to be multifactorial and may represent localized metastases in some, a genetic mutation resulting in the rare familial form of this disease in others, or the integration of genetic and epigenetic events within the bowel. Contrary to historical series, recent data suggest that MFT are not associated with a poorer prognosis. The challenge remains on the long-term surveillance of these unique tumours.

How to Manage Small Intestine (Jejunal and Ileal) Neuroendocrine Neoplasms Presenting with Liver Metastases?

PURPOSE OF REVIEW

Small intestinal neuroendocrine neoplasms (siNENs) are slowly growing tumours with a low malignant potential. However, more than half of the patients present with distant metastases (stage IV) and nearly all with locoregional lymph node (LN) metastases at the time of surgery. The value of locoregional treatment is discussed controversially.

RECENT FINDINGS

In stage I to III disease, locoregional surgery was currently shown to be curative prolonging survival. In stage IV disease, surgery may prolong survival in selected patients with the chance to cure locoregional disease besides radical/debulking liver surgery. It may improve the quality of life and may prevent severe local complications resulting in a state of chronic malnutrition and severe intestinal ischaemia or bowel obstruction. Locoregional tumour resection offers the opportunity to be curative or to focus therapeutically on liver metastasis, facilitating various other therapeutic modalities. Risks and benefits of the surgical intervention need to be balanced individually.

Update on Incidence, Prevalence, Treatment and Survival of Patients with Small Bowel Neuroendocrine Neoplasms in the Netherlands

BACKGROUND

Small bowel neuroendocrine neoplasms (SB-NEN) are rare cancers, population-based studies are needed to study this rare indolent disease. The aim of this study was to explore trends in epidemiology, treatment and survival outcomes of patients with SB-NEN based on Dutch nationwide data.

PATIENTS AND METHODS

Patients with grade 1 or 2 SB-NEN diagnosed between 2005 and 2015 were retrieved from the Netherlands Cancer Registry and linked to The Nationwide Network and Registry of Histo- and Cytopathology in the Netherlands. Age-adjusted incidence rates were calculated based using the direct standardization method. Survival analyses were performed with the Kaplan-Meier method.

RESULTS

A total of 1132 patients were included for epidemiological analyses. The age-adjusted incidence rate of SB-NEN increased from 0.52 to 0.81 per 100.000 person-years between 2005 and 2015. Incidence was higher for males than females (0.93 vs. 0.69 in 2015). Most patients had grade 1 tumours (83%). Surgery was performed in 86% of patients, with resection of the primary tumour in 99%. During the study period, administration of somatostatin analogues (SSAs) increased from 5 to 22% for stage III and from 27 to 63% for stage IV disease. Mean follow-up was 61 (standard deviation 38) months. Survival data were complete for 975/1132 patients and five-year overall survival was 75% for stage I-II, 75% for stage III and 57% for stage IV.

CONCLUSIONS

This study shows an increase in the incidence of SB-NEN in the Netherlands. A predominant role of surgery was found in all disease stages. Use of SSAs has increased over time.

The Role of Endoscopy in Small Bowel Neuroendocrine Tumors

Small bowel neuroendocrine tumors (NETs) represent approximately one-third of NETs of the gastrointestinal tract, and their incidence is increasing. When determining if endoscopic resection is appropriate, endoscopic ultrasound is used to assess the lesion size and depth of invasion for duodenal NETs. A number of techniques, including endoscopic mucosal resection (EMR), band-assisted EMR (band-EMR), endoscopic submucosal dissection (ESD), and over-the-scope clip-assisted endoscopic full-thickness resection (EFTR), have been studied; however, the best technique for endoscopic resection remains unclear. The vast majority of currently available data are retrospective, and prospective studies with longer follow-up times are required. For jejunal and ileal NETs, endoscopic techniques such as video capsule endoscopy (VCE) and balloon enteroscopy (BE) assist in diagnosis. This includes localization of the primary NET in metastatic disease where initial workup has been negative, and the identification of multifocal disease, which may change management and prognostication.

Evaluating Nationwide Application of Minimally Invasive Surgery for Treatment of Small Bowel Neuroendocrine Neoplasms

Aim

Open resection of small bowel neuroendocrine neoplasms (SB-NEN) is still considered standard-of-care, mainly because of frequently encountered multifocality and central mesenteric masses. The aim of this study was to evaluate surgical approach for SB-NEN at a national level and determine predictors for overall survival.

Methods

Patients with SB-NEN who underwent resection between 2005 and 2015 were included from the Netherlands Cancer Registry. Patient and tumor characteristics were compared between laparoscopic and open approach. Overall survival was assessed by Kaplan–Meier and compared with the Log-rank test. Independent predictors were determined by Cox proportional hazards model.

Results

In total, 482 patients were included, of whom 342 (71%) underwent open and 140 (29%) laparoscopic resection. The open resection group had significantly more multifocal tumors resected (24% vs. 14%), pN2 lymph nodes (18% vs. 7%) and stage IV disease (36% vs. 22%). Overall survival after open resection was significantly shorter compared to laparoscopic resection (3-year: 81% vs. 89%, 5-year: 71% vs. 84%, p = 0.004). In multivariable analysis, age above 60-years (60–75, HR 3.38 (95% CI 1.84–6.23); > 75 years, HR 7.63 (95% CI 3.86–15.07)), stage IV disease (HR 1.86 (95% CI 1.18–2.94)) and a laparoscopic approach (HR 0.51 (95% CI 0.28–0.94)) were independently associated with overall survival, whereas multifocal primary tumor, grade and resection margin status were not.

Conclusion

Laparoscopic resection was the approach in 29% of SB-NEN at a national level with selection of the more favorable patients. Laparoscopic resection remained independently associated with better overall survival besides age and stage, but residual confounding cannot be excluded.

Laparoscopic assisted balloon enteroscopy to detect obscure gastrointestinal bleeding sources missed by capsule endoscopy

Jejunoileal neuroendocrine tumours (NETs) are frequently multifocal and represent a consistent source of obscure gastrointestinal bleeding (OGIB). We report the real-life case of a female presenting to our attention for severe episodes of haematochezia caused by multiple localisation of jejunoileal NETs. A discrepancy between pre-operative total body contrast-enhancement computed tomography scan and capsule endoscopy (CE) emerged, in terms of numbers of lesions, so that, as completeness, an intraoperative balloon-assisted enteroscopy (BAE) was carried out, leading to the detection of the multiple lesions missed during CE. In case of obscure gastrointestinal bleeding sources missed by capsule endoscopy, laparoscopic-assisted balloon enteroscopy plays an essential role, allowing both to assess a precise diagnosis and to resect the intestinal bleeding tract.

Clinical Features, Management, and Molecular Characteristics of Familial Small Bowel Neuroendocrine Tumors

Small bowel neuroendocrine tumors are rare tumors with an increasing incidence over the last several decades. Early detection remains challenging because patients commonly develop symptoms late in the disease course, often after the tumors have metastasized. Although these tumors were thought to arise from sporadic genetic mutations, large epidemiological studies strongly support genetic predisposition and increased risk of disease in affected families. Recent studies of familial small bowel neuroendocrine tumors have identified several novel genetic mutations. Screening for familial small bowel neuroendocrine tumors can lead to earlier diagnosis and improved patient outcomes. This review aims to summarize the current knowledge of molecular changes seen in familial small bowel neuroendocrine tumors, identify clinical features specific to familial disease, and provide strategies for screening and treatment.

Unifocal versus Multiple Ileal Neuroendocrine Tumors Location: An Embryological Origin

INTRODUCTION

Small-intestinal neuroendocrine tumors (SI-NET) are situated preferentially within the ileum. The aim was to describe a potential difference in location between unifocal and multiple ileal-NET.

PATIENTS AND METHODS

Between December 2010 and December 2019, all consecutive patients who underwent resection in our European Neuroendocrine Tumor Society Center of Excellence, of at least 1 non-duodenal SI-NET, were retrospectively included. The main objective was to prove that multiple ileal-NET were mostly located on the left side of the superior mesenteric artery (SMA) axis (defined as 40 cm from the ileocecal valve), and unifocal ones on the right side.

RESULTS

Ninety-four patients were included, 6 with unifocal jejunal-NET located 35 cm (range, 10-60) from the duodenojejunal angle (DJA), 44 (47%) with unifocal ileal-NET and 44 (47%) with multiple ileal-NET. The median number of tumors in multiple ileal-NET was 7 (range, 2-95), within a median small bowel segment of 105 cm (10-240). The median length between the proximal tumor and the DJA was 428 cm (300-635) and 540 cm (350-725) for the distal one; 40 (91%) of them were located on the left side of the SMA axis. In contrast, unifocal ileal-NET were located at a median distance of 577 cm (305-820) from the DJA (p < 0.001, compared to multiple ileal-NET); 30 (68%) of them were on the right side of the SMA axis (p < 0.001).

CONCLUSION

Multiple ileal-NET are mostly located on the left side of the SMA axis. Further studies are warranted to explore the embryological origin of unifocal versus multiple ileal-NET.

Development of a drug-device combination for fluorescence-guided surgery in neuroendocrine tumors

SIGNIFICANCE

The use of cancer-targeted contrast agents in fluorescence-guided surgery (FGS) has the potential to improve intraoperative visualization of tumors and surgical margins. However, evaluation of their translational potential is challenging.

AIM

We examined the utility of a somatostatin receptor subtype-2 (SSTR2)-targeted fluorescent agent in combination with a benchtop near-infrared fluorescence (NIRF) imaging system to visualize mouse xenografts under conditions that simulate the clinical FGS workflow for open surgical procedures.

APPROACH

The dual-labeled somatostatin analog, Ga67-MMC(IR800)-TOC, was injected into mice (n  =  24) implanted with SSTR2-expressing tumors and imaged with the customized OnLume NIRF imaging system (Madison, Wisconsin). In vivo and ex vivo imaging were performed under ambient light. The optimal dose (0.2, 0.5, and 2 nmol) and imaging time point (3, 24, 48, and 72 h) were determined using contrast-to-noise ratio (CNR) as the image quality parameter. Video captures of tumor resections were obtained to provide an FGS readout that is representative of clinical utility. Finally, a log-transformed linear regression model was fitted to assess congruence between fluorescence readouts and the underlying drug distribution.

RESULTS

The drug-device combination provided high in vivo and ex vivo contrast (CNRs  >  3, except lung at 3 h) at all time points with the optimal dose of 2 nmol. The optimal imaging time point was 24-h post-injection, where CNRs  >  6.5 were achieved in tissues of interest (i.e., pancreas, small intestine, stomach, and lung). Intraoperative FGS showed excellent utility for examination of the tumor cavity pre- and post-resection. The relationship between fluorescence readouts and gamma counts was linear and strongly correlated (n  =  334, R2  =  0.71; r  =  0.84; P  <  0.0001).

CONCLUSION

The innovative OnLume NIRF imaging system enhanced the evaluation of Ga67-MMC(IR800)-TOC in tumor models. These components comprise a promising drug-device combination for FGS in patients with SSTR2-expressing tumors.

Surgical Principles in the Management of Small Bowel Neuroendocrine Tumors

OPINION STATEMENT

Small bowel neuroendocrine tumors (SB NETs) are increasing in frequency and becoming more common in surgical practice. It is often difficult to make the diagnosis of a SB NET at an early stage, as the primary tumor tends to be small and patients are asymptomatic until there is regional or distant metastasis, when they develop abdominal pain, partial obstruction, or bleeding and/or develop carcinoid syndrome. Despite this advanced presentation at the time of diagnosis, patients with metastatic SB NETs, as compared to other gastrointestinal malignancies, have favorable survival, which can be improved by appropriate surgical interventions. With the lack of randomized studies, there is reasonable controversy surrounding the optimal management of patients with SB NETs. As such, treatment of these patients is driven primarily by physician experience and available data based predominantly on retrospective studies. Based on this, current recommendations advocate for patients with SB NETs (localized or metastatic) to be managed at experienced centers by a multidisciplinary team. Eligible patients should undergo surgical resection of primary and regional disease as outlined in this article. Additionally, patients with metastatic disease should be evaluated on a case by case basis to evaluate surgical options that may mitigate bowel symptoms (i.e., pain, intestinal angina, obstruction) and carcinoid symptoms (flushing, diarrhea, hemodynamic instability) and prolong survival. Unlike other gastrointestinal malignancies, aggressive surgical management of these patients, even in the context of unresectable metastatic disease, can improve patients' symptoms and long-term survival. The principles outlined in this article are geared to guide appropriate management of SB NET patients with improvement in quality of life and overall survival outcomes.

Patterns of chromosome 18 loss of heterozygosity in multifocal ileal neuroendocrine tumors

Ileal neuroendocrine tumors (NETs) represent the most common neoplasm of the small intestine. Although up to 50% of patients with ileal NETs are diagnosed with multifocal disease, the mechanisms by which multifocal ileal NETs arise are not yet understood. In this study, we analyzed genome-wide sequencing data to examine patterns of copy number variation in 40 synchronous primary ileal NETs derived from three patients. Chromosome (chr) 18 loss of heterozygosity (LOH) was the most frequent copy number alteration identified; however, not all primary tumors from the same patient had evidence of this LOH. Our data revealed three distinct patterns of chr18 allelic loss, indicating that primary tumors from the same patient can present different LOH patterns including retention of either parental allele. In conclusion, our results are consistent with the model that multifocal ileal NETs originate independently. In addition, they suggest that there is no specific germline allele on chr18 that is the target of somatic LOH.

Small Bowel Enteroscopy - A Joint Clinical Guideline from the Spanish and Portuguese Small Bowel Study Groups

The present evidence-based guidelines are focused on the use of device-assisted enteroscopy in the management of small-bowel diseases. A panel of experts selected by the Spanish and Portuguese small bowel study groups reviewed the available evidence focusing on the main indications of this technique, its role in the management algorithm of each indication and on its diagnostic and therapeutic yields. A set of recommendations were issued accordingly.

Workup of Gastroenteropancreatic Neuroendocrine Tumors

Neuroendocrine tumors of the gastrointestinal tract or pancreas are rare. Their presentation overlaps with other intra-abdominal neoplasms, but can have unique features. The workup involves recognition of unusual clinical features associated with the tumors, imaging, analysis of blood or urine concentrations, and biopsy. Functional imaging takes advantage of the neuroendocrine tumor-specific expression of somatostatin receptors. There are characteristic features supporting the diagnosis on contrast-enhanced cross-sectional imaging. The use of tumor markers for biochemical diagnosis requires an understanding of the confounding variables affecting these assays. There are unique and specific immunohistochemical staining and grading requirements for appropriate diagnosis of these tumors.

Robotic-assisted complete mesocolic excision, central vascular ligation and para-aortic lymph node dissection in multifocal carcinoid: A case report and technical description

•

Neuroendocrine tumours are the most common type of small bowel neoplasm.

•

Robotic technique may be superior to open technique for lymph node dissection.

•

Robotic-assisted complete mesocolic excision is a safe and effective technique.

Introduction

Neuroendocrine tumours are the most common type of primary small bowel neoplasm. Consensus guidelines recommend a multimodal approach to treatment of such tumours, with aggressive surgical resection remaining the mainstay of management. There is evidence that complete mesocolic excision (CME) of lymph nodes is associated with superior oncological outcomes including longer disease-free survival in patients with colorectal cancer than standard lymph node dissection and there is increasing evidence to suggest that the robotic approach may be superior to laparoscopic or open CME. This report discusses a robotic-assisted approach to CME with central vessel ligation (CVL) and para-aortic lymph node dissection in a case of multifocal neuroendocrine tumour of the small bowel.

Presentation of case and technical approach

This report details the case of a 73-year-old male with multifocal small bowel neuroendocrine tumour. He underwent a robotic-assisted right hemicolectomy, small bowel resection, CME, CVL and para-aortic lymph node dissection. The approach described involved undertaking CME, CVL and bowel resection with a standard right hemicolectomy robotic set-up before re-docking the robot to perform the retroperitoneal para-aortic lymph node dissection.

Discussion

This case highlights the management of multifocal small bowel neuroendocrine tumour using a robotic approach for surgical resection and lymph node clearance.

Conclusion

The robotic approach provides a safe and effective technique for undertaking surgical resection of small bowel neuroendocrine tumour as well as complete mesocolic excision of lymph nodes. With a change in port positions, a robotic approach can be utilised for CME/CVL as well as retroperitoneal node dissection.

Neuroendocrine Neoplasms of the Small Bowel and Pancreas

The traditionally promulgated perspectives of neuroendocrine neoplasms (NEN) as rare, indolent tumours are blunt and have been outdated for the last 2 decades. Clear increments in their incidence over the past decades render them increasingly clinically relevant, and at initial diagnosis many present with nodal and/or distant metastases (notably hepatic). The molecular pathogenesis of these tumours is increasingly yet incompletely understood. Those arising from the small bowel (SB) or pancreas typically occur sporadically; the latter may occur within the context of hereditary tumour predisposition syndromes. NENs can also be associated with endocrinopathy of hormonal hypersecretion. Tangible advances in the development of novel biomarkers, functional imaging modalities and therapy are especially applicable to this sub-set of tumours. The management of SB and pancreatic neuroendocrine tumours (NET) may be challenging, and often comprises a multidisciplinary approach wherein surgical, medical, interventional radiological and radiotherapeutic modalities are implemented. This review provides a comprehensive overview of the epidemiology, pathophysiology, diagnosis and treatment of SB and pancreatic NETs. Moreover, we provide an outlook of the future in these tumour types which will include the development of precision oncology frameworks for individualised therapy, multi-analyte predictive biomarkers, artificial intelligence-derived clinical decision support tools and elucidation of the role of the microbiome in NEN development and clinical behaviour.

Prognostic role of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in patients with midgut neuroendocrine tumors undergoing resective surgery

AIM

Several studies demonstrated the prognostic value of the neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and platelet-to-white blood cells ratio (PWR) in different types of tumors. However, there is no information about a possible role of NLR, PLR and PWR as predictor of presence of metastasis or multifocal disease in patients undergoing surgery with curative intent for midgut NET. The aim of our study was to test the role of preoperative NLR, PLR and PWR as predictors of patients undergoing surgery with curative intent for midgut NET.

METHODS

We retrospectively enrolled seven foregut, 35 midgut and six hindgut NET patients with gastrointestinal neuroendocrine tumors operated in our Units from January 2005 to June 2016. Details about preoperative laboratory data, surgical operation, histology and follow-up were retrieved. Non-parametric statistics, ROC curve analysis and survival analysis were used.

RESULTS

NLR was significantly higher in patients with distant metastasis (p = 0.04). The ROC curve analysis indicated that a threshold value of NLR of 2.6 predicted the presence of peritoneal metastasis with a specificity of 100% and a sensitivity of 71% and an overall accuracy of AUC = 0.81 (95%CI: 0.59-0.94), p = 0.05. PLR and PWR was not be associated to metastasis but tended to be associated to multifocal disease.

CONCLUSION

In patients with midgut NET, an impaired adaptive immune response, as suggested by a high NLR ratio, was associated to the presence of distant metastasis and in particular of peritoneal metastasis. This information may be helpful when planning the treatment of a patient with a midgut NET.

Neuropilin-2 contributes to tumor progression in preclinical models of small intestinal neuroendocrine tumors

The identification of novel regulators of tumor progression is a key challenge to gain knowledge on the biology of small intestinal neuroendocrine tumors (SI-NETs). We recently identified the loss of the axon guidance protein semaphorin 3F as a protumoral event in SI-NETs. Interestingly the expression of its receptor neuropilin-2 (NRP-2) was still maintained. This study aimed at deciphering the potential role of NRP-2 as a contributor to SI-NET progression. The role of NRP-2 in SI-NET progression was addressed using an approach integrating human tissue and serum samples, cell lines and in vivo models. Data obtained from human SI-NET tissues showed that membranous NRP-2 expression is present in a majority of tumors, and is correlated with invasion, metastatic abilities, and neovascularization. In addition, NRP-2 soluble isoform was found elevated in serum samples from metastatic patients. In preclinical mouse models of NET progression, NRP-2 silencing led to a sustained antitumor effect, partly driven by the downregulation of VEGFR2. In contrast, its ectopic expression conferred a gain of aggressiveness, driven by the activation of various oncogenic signaling pathways. Lastly, NRP-2 inhibition led to a decrease of tumor cell viability, and sensitized to therapeutic agents. Overall, our results point out NRP-2 as a potential therapeutic target for SI-NETs, and will foster the development of innovative strategies targeting this receptor. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Should Ki67 immunohistochemistry be performed on all lesions in multifocal small intestinal neuroendocrine tumours?

AIMS

Well-differentiated small intestinal neuroendocrine tumours (SI-NETs) are often multifocal, and this has been suggested to impart worse disease-free survival. Practice guidelines have not been established for World Health Organisation (WHO) grading of multiple primary lesions.

METHODS AND RESULTS

We identified 68 patients with ileal/jejunal SI-NET for a combined total of 207 primary lesions. Each case was evaluated for patient age and sex; size of all tumours; presence of lymph node metastases, mesenteric tumour deposits or distant metastases; and disease-specific outcome. Ki67 staining was performed on all 207 primary lesions. The relationship between multifocality and clinicopathological factors was compared using Fisher's exact test. Outcome was tested using Cox proportional hazard regression. Forty-two patients had unifocal disease, and 26 had multifocal disease (median five lesions, range = 2-32). Most tumours were WHO grade 1 (201 of 207, 97%). Of the five patients with grades 2/3 tumours, three patients had unifocal disease, one patient had two subcentimetre grade 2 lesions (including the largest) and eight subcentimetre grade 1 lesions, and one patient had one 1.6-cm grade 3 lesion and one subcentimetre grade 1 lesion. There was a positive correlation between tumour size and Ki67 index (coefficient 0.28; 95% confidence interval 0.05-0.52, P = 0.017). There was no significant association between multifocality and nodal metastases, mesenteric tumour deposits, distant metastases or disease-specific survival.

CONCLUSIONS

In patients with multifocal SI-NET, unless a particular lesion has a high mitotic rate, only staining the largest lesion for Ki67 should serve to grade almost all cases accurately. Multifocality does not appear to significantly impact patient survival.