Familial risk of small intestinal carcinoid and adenocarcinoma

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.

Mixed neuroendocrine and adenocarcinoma of gastrointestinal tract: A complex diagnosis and therapeutic challenge

In this editorial we comment on the manuscript describing a case of adenocarcinoma mixed with a neuroendocrine carcinoma of the gastroesophageal junction. Mixed neuroendocrine and non-neuroendocrine neoplasms of the gastrointestinal system are rare heterogeneous group of tumors characterized by a high malignant potential, rapid growth, and poor prognosis. Due to the rarity of these cancers, the standard therapy is poorly defined. The diagnosis of these tumors is based on combination of morphological features, immunohistochemical and neuroendocrine and epithelial cell markers. Both endocrine and epithelial cell components can act independently of each other and thus, careful grading of each component separately is required. These cancers are aggressive in nature and the potential of each component has paramount importance in the choice of treatment and response. Regardless of the organ of origin, these tumors portend poor prognosis with increased proportion of neuroendocrine component. Multidisciplinary services and strategies are required for the management of these mixed malignancies to provide the best oncological outcomes. The etiopathogenesis of these mixed tumors remains obscure but poses interesting question. We briefly discuss a few salient points in this editorial.

Understanding the increasing incidence of neuroendocrine tumors

INTRODUCTION

Neuroendocrine tumors (NETs) are a diverse group of tumors with origins from different primary sites such as gastro-entero-pancreatic, lung and endocrine tissue. Worldwide, their incidence has increased in recent decades. Advances in imaging and better clinical awareness are traditionally attributed to this trend; however, other factors such as genetic and environmental contributors are appreciated as well.

AREAS COVERED

The purpose of this article is to review the worldwide epidemiologic trends in incidence of NET through the decades and discuss the various factors potentially contributing to the observed changes in incidence trends.

EXPERT OPINION

Overall, the incidence of NET has increased across the globe over the last few decades. Although multiple genetics and environmental factors have been proposed, the majority of this increase in incidence is secondary to earlier detection. Future studies will help in more accurate assessments and an improved understanding of disease incidence among patients with different grades and differentiation.

Survival in Colon, Rectal and Small Intestinal Cancers in the Nordic Countries through a Half Century

Background: Survival studies in intestinal cancers have generally shown favorable development, but few studies have been able to pinpoint the timing of the changes in survival over an extended period. Here, we compared the relative survival rates for colon, rectal and small intestinal cancers from Denmark (DK), Finland (FI), Norway (NO) and Sweden (SE). Design: Relative 1-, 5- and 5/1-year conditional survival data were obtained from the NORDCAN database for the years 1971-2020. Results: The 50-year survival patterns were country-specific. For colon and rectal cancers, the slopes of survival curves bended upwards for DK, were almost linear for NO and bended downwards for FI and SE; 5-year survival was the highest in DK. Survival in small intestinal cancer was initially below colon and rectal cancers but in FI and NO it caught up toward the end of the follow-up. Conclusions: Relative survival in intestinal cancers has developed well in the Nordic countries, and DK is an example of a country which in 20 years was able to achieve excellent survival rates in colon and rectal cancers. In the other countries, the increase in survival curves for colon and rectal cancer has slowed down, which may be a challenge posed by metastatic cancers.

Clinical Implications of Pathogenic Germline Variants in Small Intestine Neuroendocrine Tumors (SI-NETs)

PURPOSE

An inherited basis for presumed sporadic neuroendocrine tumor (NET) has been suggested by evidence of familial clustering of NET and a higher incidence of second malignancies in patients and families with NET. To further investigate a potential heritable basis for sporadic neuroendocrine tumors, we performed multigene platform germline analysis to determine the frequency of hereditary susceptibility gene variants in a cohort of patients with sporadic small intestine NET (SI-NET).

METHODS

We performed a multigene platform germline analysis with Invitae's 83-gene, next-generation sequencing panel using DNA from 88 individuals with SI-NET from a clinically annotated database of patients with NET evaluated at Dana-Farber Cancer Institute (DFCI) who are considered high risk for inherited variants. Additionally, we evaluated the prevalence of pathogenic variants in an unselected cohort of patients with SI-NET who underwent testing with Invitae.

RESULTS

Of the 88 patients in the DFCI cohort, a pathogenic germline variant was identified in eight (9%) patients. In an independent cohort of 120 patients with SI-NET, a pathogenic germline variant was identified in 13 (11%) patients. Pathogenic variants were identified in more than one patient in the following genes: ATM, RAD51C, MUTYH, and BLM. Somatic testing of tumors from the DFCI cohort was suboptimal because of insufficient coverage of all targeted exons, and therefore, analysis was limited.

CONCLUSION

We demonstrate a 9%-11% incidence of pathogenic germline variants in genes associated with inherited susceptibility for malignancy not previously described in association with SI-NET. The association of these germline variants with neuroendocrine carcinogenesis and risk is uncertain but warrants further characterization.

Differential methylation of G-protein coupled receptor signaling genes in gastrointestinal neuroendocrine tumors

Neuroendocrine tumors (NETs) of the small intestine undergo large chromosomal and methylation changes. The objective of this study was to identify methylation differences in NETs and consider how the differentially methylated genes may impact patient survival. Genome-wide methylation and chromosomal copy number variation (CNV) of NETs from the small intestine and appendix were measured. Tumors were divided into three molecular subtypes according to CNV results: chromosome 18 loss (18LOH), Multiple CNV, and No CNV. Comparison of 18LOH tumors with MultiCNV and NoCNV tumors identified 901 differentially methylated genes. Genes from the G-protein coupled receptor (GPCR) pathways are statistically overrepresented in the differentially methylated genes. One of the highlighted genes from the GPCR pathway is somatostatin (SST), a clinical target for NETs. Patient survival based on low versus high methylation in all samples identified four significant genes (p < 0.05) OR2S2, SMILR, RNU6-653P, and AC010543.1. Within the 18LOH molecular subtype tumors, survival differences were identified in high versus low methylation of 24 genes. The most significant is TRHR (p < 0.01), a GPCR with multiple FDA-approved drugs. By separating NETs into different molecular subtypes based on chromosomal changes, we find that multiple GPCRs and their ligands appear to be regulated through methylation and correlated with survival. These results suggest opportunities for better treatment strategies for NETs based on molecular features.

A rare case of metachronous neuroendocrine tumor after a colorectal adenocarcinoma: qualitative critical review of synchronous and metachronous gastrointestinal NET

Gastrointestinal neuroendocrine tumor (NET) associated with a metachronous intestinal adenocarcinoma is rare. We report the case of a 71-year-old man with an ileal NET. Patient has previously undergone a left colectomy for sigmoid cancer. We report a complete review both of the metachronous and synchronous NET. A comprehensive systematic literature search in PubMed, EMBASE, and MEDLINE identified a total of 35 relevant studies. This study includes an analysis of review articles, case reports, case series, retrospective studies and population-based studies. In the English literature to date, there are 21 case reports (19 synchronous cases and 2 metachronous cases), 3 case series and 3 review articles, and less than 10 retrospective studies or population-based studies. A total of 31 patients in 24 articles were included in the study: 28 patients with a synchronous gastrointestinal NET and colorectal adenocarcinoma and 3 patients with metachronous gastrointestinal NET and colorectal adenocarcinoma. The incidence of synchronous cancer (particularly for colorectal and gastric cancer) with a gastrointestinal NET ranges from 10 to 50%, while for the metachronous ones it is still unclear. This is the third metachronous case report and the first descriptive case of gastrointestinal NET diagnosed 2 years after a colorectal adenocarcinoma. An endoscopic follow-up program for gastrointestinal NET patients and/or for first-degree relatives of NET patients appears recommendable.

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.

Early life exposures associated with risk of small intestinal neuroendocrine tumors

Small intestinal neuroendocrine tumors (SINT) are rare with incidence increasing over the past 40 years. The purpose of this work is to examine the role of environmental exposures in the rise of SINT incidence using the Utah Population Database, a resource of linked records including life events, cancer diagnoses and residential histories. SINT cases born in Utah were identified through the Utah Cancer Registry with: diagnosis years of 1948 to 2014 and age at diagnosis of 23 to 88 years. Controls were matched to cases 10:1 based on sex, birth year and residence time in Utah. Cases and controls were geocoded to their birth locale. An isotonic spatial scan statistic was used to test for the occurrence and location(s) of SINT clusters. Potential environmental exposures and economic conditions in the birth locales at the time of the birth (1883–1982) were generated using historical references. Conditional logistic regression was used to estimate odd ratios. We report a spatial cluster central to historic coal mining communities, associated with a 2.86 relative risk (p = 0.016) of SINT. Aspatial analyses of industry and mining exposures further suggest elevated risk for early life exposure near areas involved in the construction industry (OR 1.98 p = 0.024). Other exposures approached significance including coal, uranium and hard rock mining during the earliest period (1883–1929) when safety from exposures was not considered. We do observe a lower risk (OR 0.58 p = 0.033) associated with individuals born in rural areas in the most recent period (1945–1982). Environmental exposures early in life, especially those from industries such as mining, may confer an elevated risk of SINT.

Associations of Tobacco and Alcohol Use with Risk of Neuroendocrine Tumors of the Small Intestine in Utah

BACKGROUND

Incidence of small-intestine neuroendocrine tumors (SINT) has been increasing in the United States over the past 40 years, with higher incidence in Utah than elsewhere. As information about how these tumors arise is limited, elucidating lifestyle factors associated with SINT in a statewide cohort could potentially identify those at risk to help mitigate their effects.

METHODS

Cases of SINT with a carcinoid histology (8240 or 8241) diagnosed in Utah from 1996 to 2014 with no prior history of cancer within 5 years (n = 433) were matched to population controls (1:10 ratio). Tobacco and alcohol exposures before case diagnosis were identified from International Classification of Diseases codes in statewide medical records and from self-reported data captured at patient encounters beginning in 1996. Multivariate logistic regression was used to estimate risk of SINT associated with tobacco and alcohol in cases compared with controls.

RESULTS

An increased risk of SINT was observed in tobacco-exposed individuals compared with unexposed [OR, 1.44; 95% confidence interval (CI), 1.11-1.86; P = 0.006]. Those who were exposed to alcohol exhibited an increased risk of SINT (OR, 1.62; 95% CI, 1.05-2.49; P = 0.03).

CONCLUSIONS

This study supports tobacco and alcohol use as risk factors for SINT, independent of family history. However, low rates of smoking and alcohol use in Utah coupled with higher rates of SINT suggest other factors may contribute to development of these tumors.

IMPACT

Although tobacco and alcohol modestly contribute to risk, our study suggests in addition to greater detection of tumors, other as-of-yet undefined exposures may drive rising SINT incidence.

Genetic heterogeneity of primary lesion and metastasis in small intestine neuroendocrine tumors

Data on intratumoral heterogeneity of small intestine neuroendocrine tumors (SI-NETs) and related liver metastasis are limited. The aim of this study was to characterize genetic heterogeneity of 5 patients with SI-NETs. Therefore, formalin-fixed, paraffin-embedded tissue samples of primary and metastatic lesions as well as benign liver of five patients with synchronously metastasized, well differentiated SI-NETs were analyzed with whole exome sequencing. For one patient, chip based 850k whole DNA methylome analysis was performed of primary and metastatic tumor tissue as well as control tissue. Thereby, 156 single nucleotide variants (SNVs) in 150 genes were identified and amount of mutations per sample ranged from 9–34 (mean 22). The degree of common (0–94%) and private mutations per sample was strongly varying (6–100%). In all patients, copy number variations (CNV) were found and the degree of intratumoral heterogeneity of CNVs corresponded to SNV analysis. DNA methylation analysis of a patient without common SNVs revealed a large overlap of common methylated CpG sites. In conclusion, SI-NET primary and metastatic lesions show a highly varying degree of intratumoral heterogeneity. Driver events might not be detectable with exome analysis only, and further comprehensive studies including whole genome and epigenetic analyses are warranted.

Smoking, alcohol and family history of cancer as risk factors for small intestinal neuroendocrine tumors: a systematic review and meta-analysis

OBJECTIVES

Risk factors for small intestinal neuroendocrine tumors (SI-NETs) are not well understood. The aim of this systematic literature review was to identify risk factors for SI-NET and to further assess these by meta-analysis.

MATERIAL AND METHODS

PubMed and abstracts from the ENETS and NANETS were searched for studies published until May 2015. Eligible studies were selected according to the PRISMA statement.

RESULTS

Seven studies evaluating six individual populations were included (study accrual period 1980-2012) in the meta-analysis, involving 765 (range 17-325) cases and 502,282 (range 52-498,376) controls. All studies were case-control by design. The following risk factors were reported in ≥2 studies: family history of any cancer, family history of colorectal cancer, ever alcohol use and ever smoking. The pooled OR was 1.34 (95% CI: 1.12-1.60; p < .01; I² = 0.0%) for family history of any cancer, 1.43 (95% CI: 1.15-1.79; p < .01; I² = 0.0%) for family history of colorectal cancer, 1.04 (95% CI: 0.63-1.72; p = .87; I² = 65.0%) for ever alcohol use and 1.40 (95% CI: 1.06-1.86; p < .05; I² = 49.3%) for ever smoking.

CONCLUSIONS

Family history of any cancer, family history of colorectal cancer and history of ever smoking were associated with an increased risk of SI-NET by meta-analysis. Alcohol consumption was not a significant risk factor for SI-NET. However, the studies reporting smoking and alcohol had a high degree of heterogeneity. Therefore, further studies are needed for clarification of smoking and alcohol as risk factors for the occurrence of SI-NET.

Familial small-intestine carcinoids: Chromosomal alterations and germline inositol polyphosphate multikinase sequencing

BACKGROUND

Familial small-intestine neuroendocrine tumors (SI-NETs) are an exceptional inherited entity. Underlying predisposing mechanisms are unelucidated, but inositol polyphosphate multikinase (IPMK) gene alterations might promote their tumorigenesis.

METHODS

A retrospective-prospective nationwide cohort was constituted, by including patients with proven SI-NETs and at least one relative with the same disease. We performed constitutional and somatic IPMK sequencing, and somatic DNA comparative genomic hybridization (CGH).

RESULTS

We included 17 patients from 8 families, who were characterized by high prevalence (57%) of multiple SI-NETs, and high frequency of distant metastases (82%) and carcinoid syndrome (65%). No IPMK mutation was found in constitutional or tumor DNA. CGH array revealed recurrent chromosome-18 deletions but no alteration in the IPMK region.

CONCLUSION

We report here the first European series of patients with familial SI-NETs. Predisposing mechanisms may not involve the IPMK-encoding sequence or chromosomal region and might not differ from those of sporadic SI-NETs.

Genetic associations with neuroendocrine tumor risk: results from a genome-wide association study

The etiology of neuroendocrine tumors remains poorly defined. Although neuroendocrine tumors are in some cases associated with inherited genetic syndromes, such syndromes are rare. The majority of neuroendocrine tumors are thought to be sporadic. We performed a genome-wide association study (GWAS) to identify potential genetic risk factors for sporadic neuroendocrine tumors. Using germline DNA from blood specimens, we genotyped 909,622 SNPs using the Affymetrix 6.0 GeneChip, in a cohort comprising 832 neuroendocrine tumor cases from Dana-Farber Cancer Institute and Massachusetts General Hospital and 4542 controls from the Harvard School of Public Health. An additional 241 controls from Dana-Farber Cancer Institute were used for quality control. We assessed risk associations in the overall cohort, and in neuroendocrine tumor subgroups. We identified no potential risk associations in the cohort overall. In the small intestine neuroendocrine tumor subgroup, comprising 293 cases, we identified risk associations with three SNPs on chromosome 12, all in strong LD. The three SNPs are located upstream of ELK3, a transcription factor implicated in angiogenesis. We did not identify clear risk associations in the bronchial or pancreatic neuroendocrine subgroups. This large-scale study provides initial evidence that presumed sporadic small intestine neuroendocrine tumors may have a genetic etiology. Our results provide a basis for further exploring the role of genes implicated in this analysis, and for replication studies to confirm the observed associations. Additional studies to evaluate potential genetic risk factors for sporadic pancreatic and bronchial neuroendocrine tumors are warranted.

Comparison of abdominal adiposity and overall obesity in relation to risk of small intestinal cancer in a European Prospective Cohort

BACKGROUND

The etiology of small intestinal cancer (SIC) is largely unknown, and there are very few epidemiological studies published to date. No studies have investigated abdominal adiposity in relation to SIC.

METHODS

We investigated overall obesity and abdominal adiposity in relation to SIC in the European Prospective Investigation into Cancer and Nutrition (EPIC), a large prospective cohort of approximately half a million men and women from ten European countries. Overall obesity and abdominal obesity were assessed by body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR). Multivariate Cox proportional hazards regression modeling was performed to estimate hazard ratios (HRs) and 95 % confidence intervals (CIs). Stratified analyses were conducted by sex, BMI, and smoking status.

RESULTS

During an average of 13.9 years of follow-up, 131 incident cases of SIC (including 41 adenocarcinomas, 44 malignant carcinoid tumors, 15 sarcomas and 10 lymphomas, and 21 unknown histology) were identified. WC was positively associated with SIC in a crude model that also included BMI (HR per 5-cm increase = 1.20, 95 % CI 1.04, 1.39), but this association attenuated in the multivariable model (HR 1.18, 95 % CI 0.98, 1.42). However, the association between WC and SIC was strengthened when the analysis was restricted to adenocarcinoma of the small intestine (multivariable HR adjusted for BMI = 1.56, 95 % CI 1.11, 2.17). There were no other significant associations.

CONCLUSION

WC, rather than BMI, may be positively associated with adenocarcinomas but not carcinoid tumors of the small intestine.

IMPACT

Abdominal obesity is a potential risk factor for adenocarcinoma in the small intestine.

Evidence for a heritable contribution to neuroendocrine tumors of the small intestine

Small intestinal neuroendocrine tumors (SI-NETs) are rare tumors arising from the enterochromaffin cells of the gut. Having a first-degree relative with a SI-NET has been shown to confer a substantial risk arising from shared environment and genetics. Heritable risk was examined using a computerized genealogy linked to historical statewide cancer data. A population-based analysis of the observed familial clustering of SI-NETs was performed to assess the genetic risk in distant relatives. A test for significant excess relatedness of 384 individuals with genealogy data and histologically confirmed SI-NETs was performed by comparing pairwise relatedness of cases to 1000 sets of matched controls. Overall significant excess pairwise relatedness was found for the 384 cases (P<0.001) and was still observed when closer than first cousin relationships were ignored (P=0.041). Relative risks (RRs) for SI-NETs were estimated as a ratio of observed to expected number of SI-NET cases among each relationship class. Siblings have a 13.4-fold (P<0.0001) and parents have a 6.5-fold (P=0.143) RR, suggesting both genetic and environmental influences. The risk extends out to third-degree relatives with a 2.3-fold RR (P=0.008). Metachronous cancers were also reported in 26% of the SI-NET cases demonstrating an increased RR of colon, bladder, non-Hodgkin lymphoma, melanoma, and prostate cancers. Although SI-NETs are rare, relatives of these cases are at a significantly elevated risk of developing a SI-NET due to heritable genetic factors. Definition of the genetic risk factors will be an important tool for earlier diagnosis and better outcomes for SI-NETs.

Risk and Protective Factors for Small Intestine Neuroendocrine Tumors: A Prospective Case-Control Study

BACKGROUND

The incidence of small intestine neuroendocrine tumors (SI-NETs) is increasing, but few studies have investigated risk factors for their occurrence, suggesting that family history (FH) of any cancer, smoking and previous cholecystectomy are associated with an increased risk. Such studies investigated small series or examined cancer registries without direct interviews.

AIM

We therefore aimed at clarifying risk and protective factors for the occurrence of sporadic SI-NETs.

SUBJECTS AND METHODS

We performed a multicenter case-control study. Patients with a histologic diagnosis of SI-NETs were prospectively evaluated, excluding familial syndromes. Controls with non-neoplastic/non-chronic disorders seen at gastrointestinal outpatients clinics were matched for sex and age (4:1). All subjects were directly interviewed by means of a specific questionnaire on potential risk and protective factors. Cases and controls were compared by Fisher's test or Student's t test for categorical or continuous variables. Explanatory variables were analyzed by simple logistic regression analysis. A multiple logistic regression analysis was performed with an Enter model; p < 0.05 was considered significant.

RESULTS

215 SI-NET patients and 860 controls were enrolled. FH of colorectal cancer (CRC) (8.8 vs. 5.0%) and breast cancer (10.2 vs. 4.8%), heavy smoking (24.7 vs. 14.8%) and drinking >21 alcohol units per week (7.4 vs. 3.8%) were all significantly more frequent in SI-NET patients than in controls. Multivariate analysis showed that FH of CRC (OR 2.23, 95% CI 1.29-3.84, p = 0.003), FH of breast cancer (OR 2.05, 95% CI 1.13-3.69, p = 0.01) and smoking (OR 1.47, 95% CI 1.07-2.03, p = 0.01) and in particular heavy smoking (OR 1.94, 95% CI 1.29-3.84, p = 0.0008) were associated with an increased risk for carcinoid occurrence, while use of aspirin can be considered a protective factor (OR 0.20, 95% CI 0.06-0.65, p = 0.008).

CONCLUSION

FH of colorectal and breast cancer as well as smoking seem to be risk factors for the development of SI-NETs, while use of aspirin might be a protective factor. These factors partially overlap with those associated with CRC, but are different from those previously associated with pancreatic neuroendocrine tumors. These findings may suggest that the mechanisms of carcinogenesis for endocrine cells in different sites can be specific and similar to those of their exocrine counterparts.

Risk factors for neuroendocrine neoplasms: a systematic review and meta-analysis

BACKGROUND

Neuroendocrine neoplasms (NENs) are rare cancers mainly of lung and digestive tract. Little is known on risk factors. The aim of this work is to define the risk factors for NEN development by extensive review and meta-analysis of published data.

METHODS

The search was conducted on Medline, Scopus, and Web of Science following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The Newcastle-Ottawa scale was used for study quality. Meta-analyses were conducted by primary site. Odds ratio (OR), hazard ratio, risk ratio, standardized incidence ratio, and associated 95% confidence intervals (CIs) were abstracted. Data were combined and analyses carried out for risk factors considered by at least two studies. Random-effects model was adopted for study variation.

RESULTS

Of 1535 extracted articles, 24 were enrolled. Meta-analyses were possible for pancreas, small intestine, and rectum. Risk for NEN associated with: (i) family history of cancer at all investigated sites (lung, stomach, pancreas, small intestine, appendix, and colon; OR 2.12 [95% CI 1.40-3.22, I(2) = 0.0%, P = 0.681] at meta-analysis in pancreas); (ii) body mass index (BMI) or diabetes (stomach, pancreas, and small intestine; OR of 2.76 [95% CI 1.65-4.64, I(2) = 58.5%, P = 0.090] for diabetes at meta-analysis in pancreas); (iii) cigarette smoking (lung, stomach, pancreas, and small intestine; OR of 1.34 [95% CI 1.10-1.63, I(2) = 0.0%, P = 0.780] and of 1.59 [95% CI 1.07-2.37, I(2) = 32.9%, P = 0.225] for smokers versus never-smokers at meta-analysis for pancreas and small intestine); (iv) alcohol consumption (pancreas and rectum; OR of 2.44 [95% CI 1.07-5.59, I(2) = 65.8%, P = 0.054] and of 1.53 [95% CI 0.99-2.35, I(2) = 0.0%, P = 0.630] for heavy drinkers versus never-drinkers at meta-analysis for pancreas and rectum).

CONCLUSIONS

Family history of cancer is the most relevant risk factor for NEN development at all investigated sites, followed by BMI and diabetes. Cigarette smoking and alcohol consumption are potential risk factors for selected anatomical sites.

Prospective evaluation and treatment of familial carcinoid small intestine neuroendocrine tumors (SI-NETs)

BACKGROUND

The aim of this study was to prospectively screen patients with a positive family history of carcinoid small intestine neuroendocrine tumors (SI-NETs) to elucidate the benefits of early detection and operative intervention.

METHODS

A single-center, prospective trial was conducted from 2008 to 2014 that evaluated patients with 2 or more blood relatives with carcinoid SI-NETs. All eligible patients were screened with urine/serum biochemistries and various imaging modalities. Operative intervention was elected in patients found to have at least 1 positive diagnostic study.

RESULTS

Twenty-nine patients from 13 families had occult carcinoid SI-NETs (15 female, 14 male). Twenty-four of the 29 patients (83%) had multifocal disease found in either the distal jejunum or ileum. On average, 75.9 cm (range, 13-195) of bowel was resected in 1 segment. Three patients were found to have stage IV disease at operation. All stage I-IIIB patients who had R0 resections have remained disease-free, with a median follow-up of 35 months.

CONCLUSION

Familial carcinoid SI-NETs often are asymptomatic and can be diagnosed with aggressive screening. With early detection, there may be a window of opportunity for operative resection to change the natural history of this disease and even prove to be curative.

A Hereditary Form of Small Intestinal Carcinoid Associated With a Germline Mutation in Inositol Polyphosphate Multikinase

BACKGROUND & AIMS

Small intestinal carcinoids are rare and difficult to diagnose and patients often present with advanced incurable disease. Although the disease occurs sporadically, there have been reports of family clusters. Hereditary small intestinal carcinoid has not been recognized and genetic factors have not been identified. We performed a genetic analysis of families with small intestinal carcinoids to establish a hereditary basis and find genes that might cause this cancer.

METHODS

We performed a prospective study of 33 families with at least 2 cases of small intestinal carcinoids. Affected members were characterized clinically and asymptomatic relatives were screened and underwent exploratory laparotomy for suspected tumors. Disease-associated mutations were sought using linkage analysis, whole-exome sequencing, and copy number analyses of germline and tumor DNA collected from members of a single large family. We assessed expression of mutant protein, protein activity, and regulation of apoptosis and senescence in lymphoblasts derived from the cases.

RESULTS

Familial and sporadic carcinoids are clinically indistinguishable except for the multiple synchronous primary tumors observed in most familial cases. Nearly 34% of asymptomatic relatives older than age 50 were found to have occult tumors; the tumors were cleared surgically from 87% of these individuals (20 of 23). Linkage analysis and whole-exome sequencing identified a germline 4-bp deletion in the gene inositol polyphosphate multikinase (IPMK), which truncates the protein. This mutation was detected in all 11 individuals with small intestinal carcinoids and in 17 of 35 family members whose carcinoid status was unknown. Mutant IPMK had reduced kinase activity and nuclear localization, compared with the full-length protein. This reduced activation of p53 and increased cell survival.

CONCLUSIONS

We found that small intestinal carcinoids can occur as an inherited autosomal-dominant disease. The familial form is characterized by multiple synchronous primary tumors, which might account for 22%-35% of cases previously considered sporadic. Relatives of patients with familial carcinoids should be screened to detect curable early stage disease. IPMK haploinsufficiency promotes carcinoid tumorigenesis.

WHO Grade 2 Neuroendocrine Tumor in a 15-Year-Old Male: A Case Report and Literature Review

Neuroendocrine tumors, distinguished from adenocarcinomas by their neuroendocrine differentiation, are the most common pediatric epithelial malignancy that most often occurs in the appendix. In 2010, the WHO classified neuroendocrine neoplasms into three grades based on morphology, mitotic count, and Ki67 proliferation index. A 15-year-old male with a history of anemia and failure to thrive was diagnosed with a well-differentiated neuroendocrine tumor in the jejunum that invaded into the subserosal soft tissue and metastasized to four lymph nodes. Pediatric neuroendocrine tumors frequently arise within hereditary tumor syndromes with pancreatic neuroendocrine tumors being the most common. Several studies also indicate an elevated risk of small intestinal neuroendocrine tumors in which children born to a parent with a history of neuroendocrine tumors in the small intestine have a significant increased risk of developing one.