Pancreatic carcinoids (serotonin-producing pancreatic neuroendocrine neoplasms): Report of 5 cases and review of the literature

Epidemiology and Prognostic Nomogram for Predicting Long-Term Disease-Specific Survival in Patients With Pancreatic Carcinoid Tumor: A SEER-Based Study

OBJECTIVES

Pancreatic carcinoid tumor (PCT) is described as a malignant form of carcinoid tumors. However, the epidemiology and prognostic factors for PCT are poorly understood.

MATERIALS AND METHODS

The data of 2447 PCT patients were included in this study from the Surveillance, Epidemiology, and End Results database and randomly divided into a training cohort (1959) and a validation cohort (488). The epidemiology of PCT was calculated, and independent prognostic factors were identified to construct a prognostic nomogram for predicting long-term disease-specific survival (DSS) among PCT patients.

RESULTS

The incidence of PCT increased remarkably from 2000 to 2018. The 1-, 5-, and 10-year DSS rates were 96.4%, 90.3%, and 86.5%, respectively. Age at diagnosis, stage, surgery, radiotherapy, and chemotherapy were identified as independent prognostic factors to construct a prognostic nomogram. The C -indices; area under the receiver operating characteristic curves for predicting 1-, 5-, and 10-year DSS, and calibration plots of the nomogram in both cohorts indicated a high discriminatory accuracy, preferable survival predictive ability, and optimal concordances, respectively.

CONCLUSIONS

The incidence of PCT has increased rapidly since 2000. In addition, we established a practical, effective, and accurate prognostic nomogram for predicting the long-term DSS of PCT patients.

Expert Consensus Practice Recommendations of the North American Neuroendocrine Tumor Society for the management of high grade gastroenteropancreatic and gynecologic neuroendocrine neoplasms

High-grade neuroendocrine neoplasms are a rare disease entity and account for approximately 10% of all neuroendocrine neoplasms. Because of their rarity, there is an overall lack of prospectively collected data available to advise practitioners as to how best to manage these patients. As a result, best practices are largely based on expert opinion. Recently, a distinction was made between well-differentiated high-grade (G3) neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas, and with this, pathologic details, appropriate imaging practices and treatment have become more complex. In an effort to provide practitioners with the best guidance for the management of patients with high-grade neuroendocrine neoplasms of the gastrointestinal tract, pancreas, and gynecologic system, the North American Neuroendocrine Tumor Society convened a panel of experts to develop a set of recommendations and a treatment algorithm that may be used by practitioners for the care of these patients. Here, we provide consensus recommendations from the panel on pathology, imaging practices, management of localized disease, management of metastatic disease and surveillance and draw key distinctions as to the approach that should be utilized in patients with well-differentiated G3 neuroendocrine tumors vs poorly differentiated neuroendocrine carcinomas.

The Role of Somatostatin Analogues in the Control of Diarrhea and Flushing as Markers of Carcinoid Syndrome: A Systematic Review and Meta-Analysis

BACKGROUND

Somatostatin analogues (SSAs) are the cornerstone of treatment for carcinoid syndrome (CS)-related symptoms. The aim of this systematic review and meta-analysis is to evaluate the percentage of patients achieving partial (PR) or complete response (CR) with the use of long-acting SSAs in patients with CS.

METHODS

A systematic electronic literature search was conducted in PubMed, Cochrane, and Scopus to identify eligible studies. Any clinical trials reporting data on the efficacy of SSAs to alleviate symptoms in adult patients were considered as potentially eligible.

RESULTS

A total of 17 studies reported extractable outcomes (PR/CR) for quantitative synthesis. The pooled percentage of patients with PR/CR for diarrhea was estimated to be 0.67 (95% confidence interval (CI): 0.52-0.79, I₂ = 83%). Subgroup analyses of specific drugs provided no evidence of a differential response. With regards to flushing, the pooled percentage of patients with PR/CR was estimated to be 0.68 (95% CI: 0.52-0.81, I₂ = 86%). Similarly, no evidence of a significant differential response in flushing control was documented.

CONCLUSIONS

We estimate there is a 67-68% overall reduction in symptoms of CS associated with SSA treatment. However, significant heterogeneity was detected, possibly revealing differences in the disease course, in management and in outcome definition.

Metastatic medullary thyroid carcinoma: a new way forward

Medullary thyroid carcinoma (MTC) is a rare malignancy comprising 1-2% of all thyroid cancers in the United States. Approximately 20% of cases are familial, secondary to a germline RET mutation, while the remaining 80% are sporadic and also harbour a somatic RET mutation in more than half of all cases. Up to 15-20% of patients will present with distant metastatic disease, and retrospective series report a 10-year survival of 10-40% from time of first metastasis. Historically, systemic therapies for metastatic MTC have been limited, and cytotoxic chemotherapy has demonstrated poor objective response rates. However, in the last decade, targeted therapies, particularly multitargeted tyrosine kinase inhibitors (TKIs), have demonstrated prolonged progression-free survival in advanced and progressive MTC. Both cabozantinib and vandetanib have been approved as first-line treatment options in many countries; nevertheless, their use is limited by high toxicity rates and dose reductions are often necessary. New generation TKIs, such as selpercatinib or pralsetinib, that exhibit selective activity against RET, have recently been approved as a second-line treatment option, and they exhibit a more favourable side-effect profile. Peptide receptor radionuclide therapy or immune checkpoint inhibitors may also constitute potential therapeutic options in specific clinical settings. In this review, we aim to present all current therapeutic options available for patients with progressive MTC, as well as new or as yet experimental treatments.

Serotonin immunoreactive pancreatic neuroendocrine neoplasm associated with main pancreatic duct dilation: a recognizable entity with excellent long-term outcome

OBJECTIVES

Dilatation of the main pancreatic duct (MPD) is rare in pancreatic neuroendocrine neoplasm (panNEN) and may be due to different mechanisms. We compared the imaging and pathological characteristics as well as the outcome after resection of positive (S+) and negative (S-) serotonin immunoreactive panNENs causing MPD dilatation.

METHODS

This retrospective study included patients with panNEN, with MPD dilatation (≥ 4 mm) on preoperative CT/MRI and resected between 2005 and 2019. Clinical, radiological, and pathological features were compared between S+ and S- panNENs. Imaging features associated with S+ panNEN were identified using logistic regression analysis. The diagnostic performance of imaging for the differentiation of S+ and S- panNENs was assessed by ROC curve analysis. Recurrence-free survival (RFS) was compared between the two groups.

RESULTS

The final population of 60 panNENs included 20/60 (33%) S+ panNENs. S+ panNENs were smaller (median 12.5 mm vs. 33 mm; p < 0.01), more frequently hyperattenuating/intense on portal venous phase at CT/MRI (95% vs. 25%, p < 0.01), and presented with more fibrotic stroma on pathology (60.7 ± 16% vs. 40.7 ± 12.8%; p < 0.01) than S- panNENs. Tumor size was the only imaging factor associated with S+ panNEN on multivariate analysis. A tumor size ≤ 20 mm had 95% sensitivity and 90% specificity for the diagnosis of S+ panNEN. Among 52 patients without synchronous liver metastases, recurrence occurred in 1/20 (5%) with S+ panNEN and 18/32 (56%) with S- panNEN (p < 0.01). Median RFS was not reached in S+ panNENs and was 31.3 months in S- panNENs (p < 0.01).

CONCLUSIONS

In panNENs with MPD dilatation, serotonin positivity is associated with smaller size, extensive fibrotic stroma, and better long-term outcomes.

KEY POINTS

• S+ panNENs showed a higher percentage of fibrotic stroma, higher microvessel density, and lower proliferation index (Ki-67) compared to S- panNENs. • Radiologically, S+ panNENs causing dilatation of the MPD were characterized by a small size (< = 20 mm) and a persistent enhancement on portal phase on both CT and MRI. • Patients with S+ panNENs presented with longer RFS when compared to those with S- panNENs.

The Role of Serum 5-HIAA as a Predictor of Progression and an Alternative to 24-h Urine 5-HIAA in Well-Differentiated Neuroendocrine Neoplasms

Simple Summary

5-hydroxyinoloacetic acid (5HIAA) is the breakdown product of serotonin and it is traditionally measured in 24-h urinary samples in patients with neuroendocrine neoplasms (NENs). 5HIAA measurement in patient serum has recently become available and has started replacing the traditional method in many centers, as it is more convenient and often preferred by patients. In this prospective, single center study, we aimed to investigate the clinical utility of serum 5HIAA for diagnostic purposes and disease surveillance in a cohort of patients with well-differentiated NENs. Our analysis confirmed an association between serum 5HIAA and the presence of liver metastases, as well as the extent of liver tumor involvement, demonstrating that the biomarker becomes positive in advanced disease stages. However, there was no evident association between a change in serum 5HIAA and change in disease status. Additionally, with respect to diagnostic purposes as compared to urinary 5HIAA testing, there was a substantial agreement between the two methods. In conclusion, serum 5HIAA performs well compared to urinary testing for diagnostic purposes but does not seem adequate as a solo biomarker of disease progression.

Abstract

Our aim was to investigate the clinical utility of serum 5HIAA for disease surveillance and diagnostic purposes in a cohort of patients with well-differentiated neuroendocrine neoplasms (WD-NENs). Forty-eight patients with WD-NENs and concurrent serum and urinary 5HIAA testing, as well as CT/MRI imaging, were included. Analysis of matching-pairs did not reveal any association between RECIST 1.1 responses and changes in serum 5HIAA levels (p = 0.673). In addition, no correlation was evident between RECIST 1.1 responses and >10%, >25% or >50% changes in serum 5HIAA levels (Fisher’s exact test p = 0.380, p > 0.999, and p > 0.999, respectively). The presence of liver metastases and extensive liver tumor involvement were associated with higher serum 5HIAA levels (p = 0.045 and p = 0.041, respectively). We also confirmed a strong linear correlation between the measurements of serum and urine 5HIAA (n = 24, r = 0.791, p < 0.0001). The concordance rate of serum and urinary 5HIAA positivity at standardized laboratory cut-offs was 75%. In patients with normal renal function tests, the concordance between the two methods was as high as 89%, and a sensitivity and specificity of 80% and 88.9%, respectively, was evident (Cohen’s kappa coefficient = 0.685). In conclusion, serum 5HIAA performs well compared to urinary testing for diagnostic purposes, mainly in advanced disease stages, and corresponds well to liver tumor burden. However, it is not adequate to predict tumor progression.

Effect of the Tryptophan Hydroxylase Inhibitor Telotristat on Growth and Serotonin Secretion in 2D and 3D Cultured Pancreatic Neuroendocrine Tumor Cells

Serotonin, a biologically active amine, is related to carcinoid syndrome in functioning neuroendocrine tumors (NETs). Telotristat ethyl is a novel inhibitor of the tryptophan hydroxylase (TPH), a key enzyme in the production of serotonin. While its use in patients with carcinoid syndrome and uncontrolled diarrhea under somatostatin analogs (SSAs) has been recently approved, in vitro data evaluating its effectiveness are lacking. For this reason, we aimed to evaluate the effect of telotristat as monotherapy, and in combination with SSAs, on proliferation and secretion in a NET cell line model. The human pancreatic NET cell lines BON-1/QGP-1 were used as 2D and 3D cultured models; somatostatin receptor and TPH mRNA expression, as well as the potential autocrine effect of serotonin on tumor cell proliferation using a 3D culture system were evaluated. Telotristat decreased serotonin production in a dose-dependent manner at a clinically feasible concentration, without affecting cell proliferation. Its combination with pasireotide, but not with octreotide, had an additive inhibitory effect on serotonin secretion. The effect of telotristat was slightly less potent, when BON-1 cells were co-treated with octreotide. Octreotide and pasireotide had no effect on the expression of TPH. Telotristat did not have an effect on mRNA expression of somatostatin receptor subtypes. Finally, we showed that serotonin did not have an autocrine effect on NET cell proliferation on the 3D cell model. These results suggest that telotristat is an effective drug for serotonin inhibition, but the effectiveness of its combination with SST2 (somatostatin receptor subtype 2)-preferring SSA should be evaluated in more detail.

Management of Diarrhea in Patients With Carcinoid Syndrome

Neuroendocrine tumors (NETs) arise from enterochromaffin cells found in neuroendocrine tissues, with most occurring in the gastrointestinal tract. The global incidence of NETs has increased in the past 15 years, likely due to better diagnostic methods. Small-bowel NETs are frequently associated with carcinoid syndrome (CS). Carcinoid syndrome diarrhea occurs in 80% of CS patients and poses a substantial symptomatic and economic burden. Patients with CS diarrhea frequently suffer from diarrhea and flushing and report corresponding impairment in quality of life, requiring substantial changes in daily activities and lifestyle. Treatment paradigms range from surgical debulking to liver-directed therapies to treatment with somatostatin analogs, nonspecific anti-diarrheal agents, and a tryptophan hydroxylase inhibitor. Other causes of diarrhea, including steatorrhea, short bowel syndrome, and bile acid malabsorption, should be considered in NET patients with refractory diarrhea. More therapeutic options are needed for symptomatic management of patients with NETs, and better understanding of the pathophysiology can empower clinicians with improved patient care.

Charting cellular identity during human in vitro β-cell differentiation

In vitro differentiation of human stem cells can produce pancreatic β-cells; the loss of this insulin-secreting cell type underlies type 1 diabetes. Here, as a step towards understanding this differentiation process, we report the transcriptional profiling of more than 100,000 human cells undergoing in vitro β-cell differentiation, and describe the cells that emerged. We resolve populations that correspond to β-cells, α-like poly-hormonal cells, non-endocrine cells that resemble pancreatic exocrine cells and a previously unreported population that resembles enterochromaffin cells. We show that endocrine cells maintain their identity in culture in the absence of exogenous growth factors, and that changes in gene expression associated with in vivo β-cell maturation are recapitulated in vitro. We implement a scalable re-aggregation technique to deplete non-endocrine cells and identify CD49a (also known as ITGA1) as a surface marker of the β-cell population, which allows magnetic sorting to a purity of 80%. Finally, we use a high-resolution sequencing time course to characterize gene-expression dynamics during the induction of human pancreatic endocrine cells, from which we develop a lineage model of in vitro β-cell differentiation. This study provides a perspective on human stem-cell differentiation, and will guide future endeavours that focus on the differentiation of pancreatic islet cells, and their applications in regenerative medicine.

Paraneoplastic syndromes and other systemic disorders associated with neuroendocrine neoplasms

Neuroendocrine paraneoplastic syndromes (PNS) consist of metabolic disorders that accompany benign and malignant neoplasms but remain unrelated to mass effects or invasion by the primary tumor or its metastases. The underlying pathogenesis responsible for PNS usual clinical presentation relies on aberrant production of protein hormones, proteins and other substances by the tumor. Prompt recognition of characteristic signs and symptoms combined with serological identification of key substances may result in early diagnosis of PNS and its underlying malignancy. For these reasons, healthcare professionals should familiarize themselves with tumor-induced hypercalcemia, syndrome of inappropriate antidiuretic hormone, carcinoid syndrome, virilisation syndrome, gynecomastia, acromegaly, Cushing syndrome, osteogenic osteomalacia, tumor-induced hypoglycemia, necrolytic migratory erythema, and watery diarrhea, hypokalemia and achlorydria syndrome. Medical awareness for PNS can improve patient outcomes through earlier administration of cancer therapy and treatment, better symptomatic relief and prolong overall survival.

Neoplasms of the Neuroendocrine Pancreas: An Update in the Classification, Definition, and Molecular Genetic Advances

This review focuses on discussing the main modifications of the recently published 2017 WHO Classification of Neoplasms of the Neuroendocrine Pancreas (panNEN). Recent updates separate pancreatic neuroendocrine tumors into 2 broad categories: well-differentiated pancreatic neuroendocrine tumors (panNET) and poorly differentiated pancreatic neuroendocrine carcinoma (panNEC), and incorporates a new subcategory of "well-differentiated high-grade NET (G3)" to the well-differentiated NET category. This new classification algorithm aims to improve the prediction of clinical outcomes and survival and help clinicians select better therapeutic strategies for patient care and management. In addition, these neuroendocrine neoplasms are capable of producing large quantity of hormones leading to clinical hormone hypersecretion syndromes. These functioning tumors include, insulinomas, glucagonomas, somatostatinomas, gastrinomas, VIPomas, serotonin-producing tumors, and ACTH-producing tumors. Although most panNENs arise as sporadic diseases, a subset of these heterogeneous tumors present as parts on inherited genetic syndromes, such as multiple endocrine neoplasia type 1, von Hippel-Lindau, neurofibromatosis type 1, tuberous sclerosis, and glucagon cell hyperplasia and neoplasia syndromes. Characteristic clinical and morphologic findings for certain functioning and syndromic panNENs should alert both pathologists and clinicians as appropriate patient management and possible genetic counseling may be necessary.

Prognostic Utility of 24-Hour Urinary 5-HIAA Doubling Time in Patients With Neuroendocrine Tumors

OBJECTIVE

New clinical prognostic tools are needed to select the population of patients with neuroendocrine tumors (NETs) that have a high risk of disease progression and disease-specific mortality (DSM). Biochemical biomarker doubling time (DT) is used clinically for prognosis prediction in several solid malignancies. The aim of the current study was to determine whether 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA) level DT has any prognostic utility in patients with NETs.

METHODS

Patients with NETs were enrolled in a prospective study with comprehensive biochemical analysis. The current analysis included 90 subjects with increasing 5-HIAA levels in two consecutive measurements. DT was calculated using the Schwartz equation. The primary outcome measures were DSM and disease progression.

RESULTS

5-HIAA DT of <434 days was associated with a higher rate of DSM ( P = .02), with positive and negative predictive values for DSM of 75 and 77%, respectively. The difference in DSM was accounted for mainly by patients with small intestine or unknown primary NET ( P = .01). In addition, a shorter 5-HIAA DT in patients with small intestine or unknown primary NET was associated with a higher risk of disease progression both in univariate ( P = .001) and multivariable analyses (hazard ratio, 15.8; 95% confidence interval, 1.3 to 198.0; P = .03).

CONCLUSION

5-HIAA DT may be used as a risk stratification tool in patients with small intestine NET or NET of unknown primary after it is validated in an independent cohort and can assist in identifying patients with a high risk for disease progression and DSM.

ABBREVIATIONS

CT = computed tomography; DSM = disease-specific mortality; DT = doubling time; 5-HIAA = 5-hydroxyindoleacetic acid; MRI = magnetic resonance imaging; NET = neuroendocrine tumor; NETUP = neuroendocrine tumor of unknown primary; PET = positron emission tomography; PFS = progression-free survival; PNET = pancreatic neuroendocrine tumor; ROC = receiver operating characteristic; SINET = small-intestine neuroendocrine tumor.

Carcinoid-syndrome: recent advances, current status and controversies

PURPOSE OF REVIEW

To review recent advances and controversies in all aspects of carcinoid-syndrome.

RECENT FINDINGS

Over the last few years there have been a number of advances in all aspects of carcinoid syndrome as well as new therapies. These include new studies on its epidemiology which demonstrate it is increasing in frequency; increasing insights into the pathogenesis of its various clinical manifestations and into its natural history: definition of prognostic factors; new methods to verify its presence; the development of new drugs to treat its various manifestations, both initially and in somatostatin-refractory cases; and an increased understanding of the pathogenesis, natural history and management of carcinoid heart disease. These advances have generated several controversies and these are also reviewed.

SUMMARY

There have been numerous advances in all aspects of the carcinoid-syndrome, which is the most common functional syndrome neuroendocrine tumors produce. These advances are leading to new approaches to the management of these patients and in some cases to new controversies.