Complications from carcinoid syndrome: review of the current evidence

Management of carcinoid heart disease

Carcinoid Heart Disease (CaHD) is defined as the constellation of all cardiac manifestations that occur in patients with carcinoid tumors. Cardiac manifestations are generally due to the paraneoplastic effects of vasoactive substances secreted by carcinoid tumors. These primarily cause cardiac valve dysfunction and resultant heart failure. Successful management of patients with CaHD requires a multidisciplinary team to address both the classical manifestations of carcinoid syndrome, as well as the additional manifestations of cardiac dysfunction. While the cornerstone of medical management for carcinoid syndrome are somatostatin analogs (SSAs), there is no evidence to suggest that the usage of SSAs influences the development or progression of CaHD. Additionally, while liver-directed therapies provide a survival benefit to symptomatic carcinoid syndrome patients with resectable disease, there are conflicting data on the survival benefit of hepatic resection among patients with CaHD. Cardiac surgery in patients with CaHD is a complex undertaking, and is the only definitive treatment for symptom management in CaHD with significant survival benefit for patients in advanced disease states. Two crucial surgical decisions to be made are determining which valve(s) should be replaced, and what prosthetic should be utilized. While challenging in this often medically frail population, cardiac surgery confers a survival benefit and should be pursued in cases of symptomatic CaHD or progressive right ventricular dysfunction.

Combined paraganglioma and IgG4-related retroperitoneal fibrosis

A paraganglioma is a neuroendocrine tumor that may secrete catecholamines and present with symptoms of sympathetic overload such as hypertension and diaphoresis. It is important that paragangliomas are identified, as they must often be treated by surgical excision. IgG4-related retroperitoneal fibrosis (IgG4-RPF) is a systemic inflammatory disease that results in the infiltration of IgG4-positive plasma cells in the retroperitoneum. Such fibrosis may adversely affect nearby organs and tissues. Here, we describe a case of combined paraganglioma and IgG4-RPF in a 47-year-old female patient. This case demonstrates the deleterious effect of these two conditions when they occur simultaneously.

Incidentally Found Rectal Carcinoid Tumor in a 46-Year-Old Female: The Potential for Complications and the Importance of Screening Guidelines

Carcinoid tumors are rare neuroendocrine tumors that can be found in the gastrointestinal tract as well as other areas throughout the body. The neurosecretory nature of these tumors can have implications for other chronic diseases that patients may have, such as diabetes. Certain treatments that may be implemented for patients who have carcinoid tumors, such as somatostatin analogs and Everolimus, can also alter blood glucose control. This highlights the importance of diagnosing and treating carcinoid tumors as early as possible to avoid complications associated with metastasis and more intense treatment. With more advanced diseases, clinicians should consider the possible effects of carcinoid tumors and their treatments on other chronic conditions as they manage the patient. For gastrointestinal carcinoid tumors, colonoscopy screening guidelines are incredibly important to counsel patients on, as resection can yield a complete cure for carcinoid tumors when they are found at an early stage. Here, we describe the case of an incidentally diagnosed rectal carcinoid tumor in a 46-year-old female patient with a history of type 2 diabetes mellitus and hypertension.

Improving outcomes in carcinoid heart disease - learning from a single centre

INTRODUCTION

A significant proportion of patients with carcinoid syndrome develop carcinoid heart disease (CHD). Valve degeneration can lead to right heart failure, and worsening prognosis. Replacement of affected valves is an effective therapy. We reviewed patients treated with valve replacement to assess prognostic factors.

METHODS

CHD patients records who underwent valve replacement from 2003-2019 were reviewed.

RESULTS

Twenty-six patients underwent valve replacement. Mean (SD) age was 61 (11) years, 54% female. Eleven tumours were grade G1, with the remaining G2. NYHA pre-surgery mean (SD) 2.0 (0.7); post-surgery mean 1.2; follow-up mean (SD) 1.6 (0.8). Mean NYHA score difference from pre- to post-surgery -0.71 ( P  = 0.002). 88.5% two (PR & TR), 3.9% one, 3.9% three and 3.9% four valves replaced. 13 patients received Lu177 oxodotreotide; 27% completed four cycles. Mortality at 1 and 5 years follow up was 42% and 50% respectively. Cox proportional hazards model of survival from surgery, adjusting for age [hazard ratio (HR) 0.96 (0.89-1.03) ( P  = 0.25)], four cycles of Lu177 oxodotreotide demonstrated HR 0.087 (0.0079-0.95) ( P  = 0.045) indicating improved survival.

DISCUSSION

Surgical patients were often NYHA grade II, and symptoms improved post-surgery. Four cycles of Lu177 oxodotreotide improved survival, although the confidence interval was wide. Further studies should be performed to assess Lu177 oxodotreotide in CHD.

Pancreatic Neuroendocrine Tumor (Pan-NET) Presented by Abdominal Pain: A Case Report and Literature Review

A pancreatic neuroendocrine tumor (Pan-NET) is a rare neoplasm originating in the neuroendocrine system. Carcinoid syndrome occurs in approximately 19% of patients with functional Pan-NETs, typically when liver metastases occur. In this paper, we describe the case of a patient with a low-grade non-functional Pan-NET, but with a typical clinical presentation of carcinoid syndrome. An 81-year-old male was admitted to our Department of Internal Medicine at Cannizzaro Hospital (Catania, Italy) because of the onset of abdominal pain with nausea, loose stools, and episodic flushing. Firstly, an abdominal contrast-enhanced CT scan showed a small pancreatic hyper-vascular mass; then, a gallium-68 DOTATOC integrated PET/CT revealed an elevated expression of SSTR receptors. Serum chromogranin A and urinary 5-HIAA measurements were negative. We performed an endoscopic ultrasonography (EUS) by a fine-needle biopsy (EUS-FNB), allowing the immunostaining of a small mass (0.8 cm) and the diagnosis of a low-grade (G1) non-functional Pan-NET (NF-Pan-NET). Surgery was waived, while a follow-up strategy was chosen. The early recognition of Pan-NETs, although rare, is necessary to improve the patient's survival. Although helpful to allow for immunostaining, EUS-FNB needs to be warranted in future studies comparing EUS-FNB to EUS-FNA (fine-needle aspiration), which is, to date, reported as the tool of choice to diagnose Pan-NETs.

Hedinger Syndrome-Lessons Learnt: A Single-Center Experience

BACKGROUND

Hedinger syndrome (HS) or carcinoid heart disease (CD) is a rare and challenging manifestation of malignant neuroendocrine tumours (NETs) involving the heart. We aimed to report our experience with surgical strategies and midterm results in HS patients.

METHODS

Eleven patients (58 ± 11 (range 41 to 79 years); 5 females) with HS who underwent cardiac surgery in our department between 07/2005 and 05/2023 were analysed.

RESULTS

All patients showed a New York Heart Association (NYHA) class III-IV and in all the tricuspid valve (TV) was involved. Four patients received a TV replacement, and three TV reconstruction. Recently, to preserve the geometry and function of the compromised right ventricle (RV), we have applied the TV "bio-prosthesis in native-valve" implantation technique with the preservation of the valve apparatus (tricuspid valve implantation: TVI) in four cases. Concomitant procedures included pulmonary valve replacement in four, pulmonary implantation in one, and aortic valve replacement in three cases. To treat RV failure, we adapted a combined TandemHeart®-CytoSorb® haemoperfusion strategy in Patient #10 and venoarterial extracorporeal membrane oxygenation (V-A ECMO) support avoidance, after experiencing an ECMO-induced carcinoid-storm-related death in Patient #8. Mortality at 30 days was 18% (2/11). The median follow up was 2 ± 2.1 years (range 1 month to 6 years) with an overall mortality during the follow-up period of 72.7% (8/11).

CONCLUSIONS

HS surgery, despite being a high-risk procedure, can efficiently prolong survival, and represents a safe and feasible procedure. However, patient selection seems to be crucial. Further follow up and larger cohorts are needed.

Carcinoid syndrome caused by a pulmonary carcinoid mimics intestinal manifestations of ulcerative colitis: A case report

BACKGROUND

Pulmonary carcinoids are rare, low-grade malignant tumors characterized by neuroendocrine differentiation and relatively indolent clinical behavior. Most cases present as a slow-growing polypoidal mass in the major bronchi leading to hemoptysis and pulmonary infection due to blockage of the distal bronchi. Carcinoid syndrome is a paraneoplastic syndrome caused by the systemic release of vasoactive substances that presents in 5% of patients with neuroendocrine tumors. Due to such nonspecific presentation, most patients are misdiagnosed or diagnosed late and may receive several courses of antibiotics to treat recurrent pneumonia before the tumor is diagnosed.

CASE SUMMARY

We report the case of a 48-year-old male who presented with cough, dyspnea, a history of recurrent pneumonitis, and therapy-refractory ulcerative colitis that completely subsided after the resection of a pulmonary carcinoid.

CONCLUSION

We report and emphasize pulmonary carcinoid as a differential diagnosis in patients with nonresponding inflammatory bowel diseases and recurrent pneumonia.

Urinary 5-Hydroxyindolacetic Acid Measurements in Patients with Neuroendocrine Tumor-Related Carcinoid Syndrome: State of the Art

Carcinoid syndrome (CS), mostly associated with small intestinal neuroendocrine tumors (SI-NETs) or lung-related NETs, is characterized by symptoms related to hormonal secretion and long-term complications, including carcinoid heart disease (CHD), which is potentially life-threatening. In the early stages of the disease, symptoms are non-specific, which leads to delayed diagnoses. The availability of reliable tumor markers is crucial for a prompt diagnosis and proper management. This review summarizes available evidence on the role of 24 h urinary 5-hydroxyindolacetic acid (24u5HIAA), which is the urinary breakdown metabolite of serotonin, in the diagnosis/follow-up of NET-related CS, with a focus on its potential prognostic role, while eventually attempting to suggest a timeline for its measurement during the follow-up of NET patients. The use of 24u5HIAA is an established biomarker for the diagnosis of NETs with CS since it shows a sensibility and specificity of 100% and 85-90%, respectively. The downside of 24u5-HIAA is represented by the need for 24 h urine collection and the risk of confounding factors (foods and medication), which might lead to false positive/negative results. Moreover, 24u5HIAA is useful in the follow-up of NETs with CS since a shorter double time correlates to a higher risk of disease progression/disease-specific mortality. Furthermore, an elevation in 24u5-HIAA is correlated with a dismal prognosis because it is associated with an increased likelihood of CHD development and disease progression/mortality. Other potentially interesting biochemical markers have been proposed, including plasmatic 5HIAA, although further standardization and prospective studies are required to define their role in the management of NETs. Meanwhile, 24u5HIAA remains the most accurate CS biomarker.

Practical considerations when providing palliative care to patients with neuroendocrine tumors in the context of routine disease management or hospice care

This serves as a white paper by the North American Neuroendocrine Tumor Society (NANETS) on the practical considerations when providing palliative care to patients with neuroendocrine tumors in the context of routine disease management or hospice care. The authors involved in the development of this manuscript represent a multidisciplinary team of patient advocacy, palliative care, and hospice care practitioners, endocrinologist, and oncologists who performed a literature review and provided expert opinion on a series of questions often asked by our patients and patient caregivers affected by this disease. We hope this document serves as a starting point for oncologists, palliative care teams, hospice medical teams, insurers, drug manufacturers, caregivers, and patients to have a frank, well-informed discussion of what a patient needs to maximize the quality of life during a routine, disease-directed care as well as at the end-of-life.

Consideration of quality-of-life in the treatment decision-making for patients with advanced gastroenteropancreatic neuroendocrine tumors

INTRODUCTION

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a complex and heterogenous family of solid malignancies that originate from neuroendocrine tissue in the gastrointestinal tract or pancreas. Most patients diagnosed with GEP-NETs present with advanced or metastatic disease, and quality of life (QoL) is often an important priority when selecting treatments for these patients. Patients with advanced GEP-NETs often experience a substantial and persistent symptom burden that undermines their QoL. Addressing a patient's individual symptoms through judicious selection of treatment may improve QoL.

AREAS COVERED

The objectives of this narrative review are to summarize the impact of advanced GEP-NETs on patient QoL, assess the potential value of current treatments for maintaining or improving patient QoL, and offer a clinical framework for how these QoL data can be translated to inform clinical decision-making for patients with advanced GEP-NETs.

EXPERT OPINION

Patients with advanced GEP-NETs experience a significant and persistent symptom burden that impacts their daily lifestyle, activities, work life, and financial health, leading to erosion of their QoL. Ongoing and future studies incorporating longitudinal QoL assessments and head-to-head treatment evaluations will further inform the incorporation of QoL into clinical decision-making.

Cardiac Roles of Serotonin (5-HT) and 5-HT-Receptors in Health and Disease

Serotonin acts solely via 5-HT₄-receptors to control human cardiac contractile function. The effects of serotonin via 5-HT₄-receptors lead to positive inotropic and chronotropic effects, as well as arrhythmias, in the human heart. In addition, 5-HT₄-receptors may play a role in sepsis, ischaemia, and reperfusion. These presumptive effects of 5-HT₄-receptors are the focus of the present review. We also discuss the formation and inactivation of serotonin in the body, namely, in the heart. We identify cardiovascular diseases where serotonin might play a causative or additional role. We address the mechanisms which 5-HT₄-receptors can use for cardiac signal transduction and their possible roles in cardiac diseases. We define areas where further research in this regard should be directed in the future, and identify animal models that might be generated to this end. Finally, we discuss in what regard 5-HT₄-receptor agonists or antagonists might be useful drugs that could enter clinical practice. Serotonin has been the target of many studies for decades; thus, we found it timely to summarise our current knowledge here.

Carcinoid Syndrome: Preclinical Models and Future Therapeutic Strategies

Carcinoid syndrome represents a debilitating paraneoplastic disease, caused by the secretion of several substances, occurring in about 10-40% of patients with well-differentiated neuroendocrine tumors (NETs). The main signs and symptoms associated with carcinoid syndrome are flushing, diarrhea, hypotension, tachycardia, bronchoconstriction, venous telangiectasia, dyspnea and fibrotic complications (mesenteric and retroperitoneal fibrosis, and carcinoid heart disease). Although there are several drugs available for the treatment of carcinoid syndrome, the lack of therapeutic response, poor tolerance or resistance to drugs are often reported. Preclinical models are indispensable tools for investigating the pathogenesis, mechanisms for tumor progression and new therapeutic approaches for cancer. This paper provides a state-of-the-art overview of in vitro and in vivo models in NETs with carcinoid syndrome, highlighting the future developments and therapeutic approaches in this field.

Analysis of Patients with NET G1/G2 Neuroendocrine Tumors of the Small Intestine in the Course of Carcinoid Heart Disease-A Retrospective Study

Neuroendocrine neoplasms of the small intestine (SI-NENs) are one of the most commonly recognized gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). Carcinoid heart disease (CHD) is the primary cause of death in patients with the carcinoid syndrome (CS). The aim of this retrospective study was to evaluate possible factors impacting upon overall survival (OS) in subjects with both neuroendocrine tumors (NETs) G1/G2 of the small intestine (SI-NET) and CHD. Enrolled in our study of 275 patients with confirmed G1/G2 SI-NET, were 28 (10%) individuals with CHD. Overall survival was assessed using the Kaplan-Meier method. The Cox-Mantel test was used to determine how OS varied between groups. A Cox proportional hazards model was used to conduct univariate analyses of predictive factors for OS and estimate hazard ratios (HRs). Of the 28 individuals with confirmed carcinoid heart disease, 12 (43%) were found to have NET G1 and 16 (57%) were found to have NET G2. Univariate analysis revealed that subjects with CHD and without resection of the primary tumor had a lower OS. Our retrospective study observed that patients who presented with CHD and without resection of primary tumor had worse prognosis of survival. These results suggest that primary tumors may need to be removed when feasible, but further research is needed. However, no solid recommendations can be issued on the basis of our single retrospective study.

177Lu-DOTATATE Efficacy and Safety in Functioning Neuroendocrine Tumors: A Joint Analysis of Phase II Prospective Clinical Trials

INTRODUCTION

Neuroendocrine tumors (NETs) are rare malignancies with different prognoses. At least 25% of metastatic patients have functioning neuroendocrine tumors (F-NETs) that secrete bioactive peptides, causing specific debilitating and occasionally life-threatening symptoms such as diarrhea and flushing. Somatostatin analogs (SSAs) are usually effective but beyond them few treatment options are available. We evaluated the clinical efficacy of 177 Lu-DOTATATE in patients with progressive metastatic F-NETs and SSA-refractory syndrome.

PATIENTS AND METHODS

A non-pre-planned joint analysis was conducted in patients enrolled in phase II clinical trials on metastatic NETs. We extrapolated data from F-NET patients with ≥1 refractory sign/symptom to octreotide, and ≥1 measurable lesion. Syndrome response (SR), overall survival (OS), progression-free survival (PFS), tolerance and disease response were analyzed.

RESULTS

Sixty-eight patients were enrolled, the majority (88.1%) with a SR. According to RECIST criteria, 1 (1.5%) patient showed a CR, 21 (32.3%) had a PR and 40 (61.5%) SD. At a median follow-up of 28.9 months (range 2.2-63.2) median PFS was 33.0 months (95%CI: 27.1-48.2). Median OS (mOS) had not been reached at the time of the analysis; the 2-year OS was 87.8% (95%CI: 76.1-94.1). Syndromic responders showed better survival than non-responders, with a 2-year OS of 93.9% (95%CI: 92.2-98.0) vs. 40.0% (95%CI: 6.6-73.4), respectively. A total of 233 adverse events were recorded. Grade 1-2 hematological toxicity was the most frequent.

CONCLUSION

The 177 Lu-DOTATATE improved symptoms and disease control in patients with F-NETs. Treatment was well tolerated. The syndrome had an impact on both quality of life and OS.

Four decades of experience with carcinoid heart disease: An analysis of 84 patients

Carcinoid heart disease (CHD) is a serious cardiac condition which is caused by elevated serotonin in the systemic circulation, secreted by neuroendocrine tumours (NET). It mostly affects the right-sided heart valves, where it causes fibrotic disturbances and is associated with worse survival. In this study, we describe a large cohort of patients with CHD and provide an insight into their survival over the past decades. All consecutive patients with a serotonin producing NET and CHD referred to the Netherlands Cancer Institute that presented with CHD or developed CHD during their follow up time were included from 1984 until 2021. Patients were divided into three time periods: 1984-2000, 2000-2010 and 2010-2018. Median N-terminal pro B-type natriuretic protein (NT-proBNP) and serum serotonin levels were stratified according to tricuspid regurgitation severity. Kaplan-Meier curves and log rank test were used for visualisation of survival. Cox regression was used for identification of the characteristics associated with disease specific mortality (DSM). A total of 84 patients with CHD were included of whom 49 (58.3%) were male. Median age at NET diagnosis was 62.3 (range 23.9-81.7) years, and median time to development of CHD was 1.1 (range 0-24.2) years. NT-proBNP was significantly higher when more severe tricuspid regurgitation (TR) was present (p = .027). Median survival from CHD diagnosis for 1984-2000, 2000-2010 and 2010-2018 were 1.3 (confidence interval [CI]: 0.9-1.6), 1.9 (CI: 1.2-2.6) and 3.9 (CI: 1.7-6.2) years (p = .025). Valve replacement surgery (VSR) occurred more frequent in later time periods. VSR (hazard ratio [HR] 0.33, p = .005) and NT-proBNP (HR 1.003, 1.00-1.005, p = .036) were significantly associated with DSM. The prognosis of patients with CHD has improved over the past decades, possibly caused by more VSR. NT-proBNP is a valuable biomarker in patients with CHD. Clinical practice should be aimed at timely diagnosis and intervention of CHD.

Elevated Serotonin and NT-proBNP Levels Predict and Detect Carcinoid Heart Disease in a Large Validation Study

Carcinoid heart disease (CHD) is a rare fibrotic cardiac complication of neuroendocrine tumors. Besides known biomarkers N-Terminal pro-B-type natriuretic peptide (NT-proBNP) and serotonin, activin A, connective tissue growth factor (CTGF), and soluble suppression of tumorigenicity 2 (sST2) have been suggested as potential biomarkers for CHD. Here, we validated the predictive/diagnostic value of these biomarkers in a case-control study of 114 patients between 1990 and 2021. Two time-points were analyzed: T0: liver metastasis without CHD for all patients. T1: confirmed CHD in cases (CHD+, n = 57); confirmed absence of CHD five or more years after liver metastasis in controls (CHD−, n = 57). Thirty-one (54%) and 25 (44%) females were included in CHD+ and CHD− patients, respectively. Median age was 57.9 years for CHD+ and 59.7 for CHD- patients (p = 0.290). At T0: activin A was similar across both groups (p = 0.724); NT-proBNP was higher in CHD+ patients (17 vs. 6 pmol/L, p = 0.016), area under the curve (AUC) 0.84, and the most optimal cut-off at 6.5 pmol/L. At T1: activin A was higher in CHD+ patients (0.65 vs. 0.38 ng/mL, p = 0.045), AUC 0.62, without an optimal cut-off value. NT-pro-BNP was higher in CHD+ patients (63 vs. 11 pmol/L, p < 0.001), AUC 0.89, with an optimal cut-off of 27 pmol/L. Serotonin (p = 0.345), sST2 (p = 0.867) and CTGF (p = 0.232) levels were similar across groups. This large validation study identified NT-proBNP as the superior biomarker for CHD. Patients with elevated serotonin levels and NT-proBNP levels between 6.5 and 27 pmol/L, and specifically >27 pmol/L, should be monitored closely for the development of CHD.

The Treatment of Psychotic Depression in a 64-Year-Old Patient With Carcinoid Syndrome

Serotonin-producing tumours are a subset of neuroendocrine tumours which, when active, can lead to carcinoid syndrome caused by the secretion of vasoactive substances such as serotonin, histamine, and bradykinins. In addition to the common symptoms of flushing, diarrhoea, abdominal pain, and carcinoid heart disease, carcinoid syndrome is also known to cause psychiatric symptoms of depression as well as anxiety and, very rarely, psychotic symptoms. The treatment of the neuropsychiatric manifestations of the disease is also complicated by the concurrent use of somatostatin analogues, which also affect total circulating serotonin levels, a neurotransmitter implicated in the aforementioned psychiatric disorders. In this case report, we will discuss the management of psychotic depression in a 64-year-old female patient with a metastatic carcinoid tumour and our rationale for the use of vortioxetine in her treatment.

Treatment of neuroendocrine tumours with 177 Lu-peptide receptor radionuclide therapy: Challenging clinical scenarios and their management

Peptide receptor radionuclide therapy (PRRT) for the treatment of patients with neuroendocrine tumours is usually well tolerated, with selection based on existing guidelines. However, there are various scenarios where the risk-benefit analysis of PRRT needs to be evaluated to limit any complications associated with PRRT. This review looks at 11 key scenarios where the risk-benefit of PRRT needs to be closely evaluated.

Simultaneous determination of tryptophan, 5-hydroxytryptophan, tryptamine, serotonin, and 5-HIAA in small volumes of mouse serum using UHPLC-ED

In this paper we report a simple and efficient method for the concurrent analysis of tryptophan, 5-HTP, tryptamine, serotonin, and 5-HIAA in mouse serum using UHPLC-ED after protein precipitation and dilution. These compounds are neuroactive and are of interest in studies of mood and behavior; They are also biomarkers for the presence of neuroendocrine tumors and are used in the diagnosis of these cancers. After a brief series of validation experiments, this method was applied to serum from mouse behaviour experiments.•

A convenient UHPLC method with electrochemical detection for concomitant analysis of the serotonin pathway in serum, including, for the first time, tryptamine.

•

The method met all performance criteria established for use in our lab and was applied in rodent experiments.

Recent Advances in the Diagnosis and Management of Carcinoid Syndrome

Carcinoid syndrome, a paraneoplastic condition linked with the release of multiple humoral factors, affects around 30-40% of patients with well-differentiated neuroendocrine tumours. Carcinoid syndrome has a major and unfavourable impact on patients' quality of life; it raises costs when compared to non-functioning neuroendocrine tumours; and it causes patients' lifestyles to alter, such as food, job, physical activity, and social life. Somatostatin analogues have been the first-line therapy for individuals with neuroendocrine tumours and carcinoid disease for decades. While these drugs give considerable relief from carcinoid syndrome symptoms, clinical progression is unavoidable, necessitating further research into newer treatment measures. Carcinoid tumours are sometimes difficult to diagnose because of their vague or nonspecific symptoms. There have been several advancements in all aspects of carcinoid syndrome, as well as novel therapeutics, in the previous few years. New epidemiological studies show that it is becoming more common; increasing insights into the pathogenesis of its various clinical manifestations and 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 the disease. An all language literature search was conducted on MEDLINE, COCHRANE, EMBASE, and Google Scholar till November 2021. The following search strings and Medical Subject Headings (MeSH) terms were used: "Recent advances", "Carcinoid syndrome", "Neuroendocrine Neoplasms" and "Carcinoid heart disease". We comprehensively reviewed the literature on the pathogenesis, clinical features, and newer treatment modalities for Carcinoid Syndrome. Recent advancements in research and management have resulted from advances in our understanding of the aetiology of carcinoid syndrome. The development of molecular indicators of aggressiveness improved serum tumour markers, and the molecular aetiology of carcinoid heart disease are all possible because of advances in molecular biology. We conducted a comprehensive review to update knowledge regarding the pathophysiology, diagnostic protocols, and current and newer treatments for carcinoid syndrome, which presently requires a multidisciplinary approach, due to the complexity of the illness's aetiology, diagnosis, and therapy.

A case of metastatic neuroendocrine disease and cholecystitis: surgical remedy and management of carcinoid crisis

The report presents a case of a 70-year-old male with a known mesenteric neuroendocrine tumour and metastases to the liver diagnosed with acute cholecystitis. During surgery, the patient developed a carcinoid crisis with mixed distributive and cardiogenic shock involving systemic vasodilation and arrhythmia. During surgical procedures, carcinoid crisis can be precipitated by tumours that secrete a pathological shower of vasoactive mediators. Somatostatin analogues are utilized to control carcinoid syndrome and are routinely used peri-operatively. However, no standard infusion regimen exists. The case raises the suggestion that metastatic liver neuroendocrine disease may confound the diagnosis of cholecystitis, complicates the management of acute surgical presentations and highlights the need for agreement on octreotide therapy for surgical patients with carcinoid tumours.

Uptake and release characteristics of serotonin hydrochloride by natural Cuban zeolite containing clinoptilolite and mordenite

Serotonin (5-HT) plays an important role in human physiology. An excess of this native regulator within the human gut can be partially controlled by orally consuming zeolite. Therefore, this study focuses on the kinetics of the uptake and release of serotonin hydrochloride (5-HT-hc) by natural Cuban zeolite containing clinoptilolite and mordenite at different pH levels using UV–Vis spectroscopy. 5-HT-hc is stable under the following investigated experimental conditions: incubation temperature of 36 °C; and at a pH of 5, 7, and 9. Independent of the zeolite framework, the 5-HT-hc is adsorbed without changing its molecular structure. The uptake and release of 5-HT-hc were not correlated to the textural properties of these aluminosilicates. The investigated zeolites adsorbed 5-HT-hc at about 14 mg per gram zeolite with no large differences observed between different samples. Release studies of 5-HT-hc-loaded zeolite revealed that the 5-HT-hc is strongly bound to the zeolite, and independent of the pH value and zeolite framework only up to 12.7% was released into the water.

A Challenging Case of Carcinoid Crisis in a Patient With Neuroendocrine Tumor

The critical state of circulatory collapse and hypoperfusion that results in end-organ damage has been called shock. Carcinoid crisis is a rare cause of shock, which is difficult to identify in the presence of infection. It occurs due to the release of vasoactive amines into the systemic circulation following an inciting event. In the presence of a neuroendocrine tumor, carcinoid crisis should be suspected in case of resistant shock. Herein, we report a rare case of carcinoid crisis, in which a quick response to the somatostatin analog therapy, octreotide, was helpful to confirm the diagnosis.

Opportunities to Improve Symptom Control with Somatostatin Congeners in GEP-NETs: A Review of Key Issues

Octreotide acetate (octreotide) is the most prescribed and most studied somatostatin congener, or analog, for gastroenteropancreatic neuroendocrine tumors (GEP‐NETs) and carcinoid syndrome, the latter of which may be characterized by debilitating diarrhea and flushing. Approved in the U.S. more than 30 years ago, octreotide is widely used to control the symptoms of carcinoid syndrome and has been shown to demonstrate antiproliferative activity. The two formulations available in the U.S. include a subcutaneous immediate‐release (IR) injection introduced in 1989 and a long‐acting repeatable (LAR) intramuscular injection approved in 1999. Lanreotide depot (lanreotide), a more recent somatostatin congener, has been available in the U.S. since 2014.

Despite widespread use of octreotide LAR, several key challenges exist with the current depot‐based treatment paradigm. Studies indicate that LAR formulations are associated with continued unmet patient needs, owing in part to a loss of bioactivity over time that may necessitate progressive supplemental treatment with IR octreotide to adequately control symptoms. Clinicians should understand the key differences in the pharmacokinetic profiles of the LAR and IR formulations that may contribute to bioactivity loss and somatostatin receptor desensitization. In addition, there is a need to re‐evaluate the role of IR octreotide in combination with depot therapy to provide consistent bioavailability and better control of carcinoid syndrome symptoms.

The purpose of this review is to explore all these issues and to re‐establish a rationale for the IR formulation, particularly with respect to novel use cases and its use during the COVID‐19 pandemic.

This review explores key challenges with depot‐based treatment of gastroenteropancreatic neuroendocrine tumors with octreotide and the key differences between the LAR and IR formulations.

Gastroenteropancreatic neuroendocrine neoplasms: A clinical snapshot

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

Gastroenteropancreatic neuroendocrine neoplasms: A clinical snapshot

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

Rare Presentation of a Metastatic Pancreatic Neuroendocrine Neoplasm Presenting with Atrial Flutter

Pancreatic neuroendocrine neoplasms (PanNENs) rarely secrete serotonin, which is the main cause of carcinoid syndrome. One of its unusual manifestations is carcinoid heart disease or Hedinger's syndrome which is seldom accompanied by cardiac arrhythmias. We report the case of an 88-year-old woman who presented with recently experienced episodes of palpitations and a newly developed atrial flutter with a ventricular rate of 130 beats per minute. Echocardiography revealed thickened and tethered tricuspid and pulmonary valve leaflets causing severe valvular regurgitation and right ventricular dilatation. Episodes of intermittent diarrhoea over the previous 2 years were mentioned, making carcinoid syndrome our working diagnosis. The 5-hydroxyindoleacetic acid (5-HIAA) levels in a 24-hour urine collection specimen were elevated. Conventional imaging studies and a Ga-68 dodecane tetraacetic acid tyrosine-3-octreotate (DOTATATE) positron emission tomography/computer tomography (PET/CT) scan revealed the presence of a metastatic PanNEN arising from the pancreatic tail. The patient was managed with lanreotide and telotristat with remarkable improvement of her symptoms. To our knowledge, this is the first reported case of carcinoid syndrome presenting with atrial flutter as the initial symptom.

LEARNING POINTS

Ultrasonography findings can indicate or lead to the diagnosis of carcinoid heart disease or Hedinger's syndrome.Clinicians should investigate rarer causes of atrial flutter when common ones are excluded.Even in advanced metastatic disease, complete remission of symptoms may be achieved with somatostatin analogues along with telotristat ethyl.

Percutaneous Image-Guided Core Needle Biopsy of Neuroendocrine Tumors: How Common Is Intraprocedural Carcinoid Crisis?

PURPOSE

To retrospectively evaluate the incidence of carcinoid crisis, other complications, and physiologic disturbances during percutaneous image-guided core needle biopsy of neuroendocrine tumors (NETs) in the lung and the liver.

MATERIALS AND METHODS

Between January 2010 and January 2020, 106 computed tomography (CT) or ultrasound (US)-guided core needle biopsies of lung and liver NETs were performed in 95 consecutive adult patients. The mean age was 64 ± 13 years, and 48% were female. The small bowel was the most common primary site (33%, 31/95), and 32 (34%) patients had pre-existing symptoms of carcinoid syndrome. The mean tumor size was 3.2 ± 2.6 cm, and mean number of passes was 3.4 ± 1.6. A 17/18-gauge needle was used in 91% (96/106) of the biopsies. Thirteen (12%) patients received either outpatient or prophylactic octreotide.

RESULTS

No patients experienced carcinoid crisis or needed octreotide, inotropes, vasopressors, or resuscitation. A single biopsy procedure (0.9%, 1/106) was complicated by bleeding that required angiographic hepatic artery embolization. Changes in pre-biopsy- versus post-biopsy systolic blood pressure and heart rate were -1.6 mm Hg (P = .390) and 0.6 beat/min (P = .431), respectively. Tumor functional status, overall tumor burden, and the elevation of neuroendocrine markers were not associated with intraprocedural physiologic disturbances. There were 4 minor complications (0.4%, 4/106) associated with the biopsy procedure that were not attributed to hormone excretion from tumor manipulation.

CONCLUSIONS

Percutaneous image-guided core biopsy of NETs is safe, with low complication rate and no definite carcinoid crisis in the current cohort.

Pellagra a review exploring causes and mechanisms, including isoniazid-induced pellagra

Pellagra is a clinical syndrome caused by a deficiency of niacin (nicotinic acid) and/or its precursor tryptophan. The cardinal manifestations are 4 D's: dermatitis, diarrhoea, dementia and in worst case death. Increased use of isoniazid prophylaxis along with antiretroviral therapy in countries where latent tuberculosis is common has been associated with increased presentations with pellagra.

Health resource utilisation by patients with neuroendocrine tumours with or without carcinoid heart disease: a multinational study

Background

Carcinoid heart disease (CHD) is a rare and severe complication from carcinoid syndrome which may be associated with high health resource utilisation (HRU). We aimed to compare HRU between patients with and without CHD.

Methods

Multicentre retrospective study of 137 consecutive patients with neuroendocrine tumours (NET) and elevated urinary 5-hydroxyindoleacetic acid treated in seven large hospitals in Latin America. We used the chi-squared test for binary variables and the Mann–Whitney test for quantitative correlations. Variables were entered into a multivariable linear regression model for higher HRU.

Results

One-third of the patients had (45) had CHD. Patients with CHD had significantly more emergency visits and echocardiograms as compared to patients without CHD. In the bivariate models, CHD (R² = 0.61, p = 0.01), private health system (R² = 0.63, p = 0.02) and simultaneous cardiovascular comorbidities (R² = 0.61, p = 0.04) were associated with a higher HRU. The multivariate model pointed out the accumulated effect of variables on HRU (R² = 0.2, p < 0.01).

Conclusions

NET patients with CHD present higher HRU independently of other clinical factors or health system. Effectively treating carcinoid syndrome, and likely delaying the onset of CHD, may potentially reduce the amount of HRU by these patients.

Role of Diet in the Management of Carcinoid Syndrome: Clinical Recommendations for Nutrition in Patients with Neuroendocrine Tumors

Nutrition and metabolism are altered in patients with gastroenteropancreatic neuroendocrine tumors, which is related to excessive production of gastrointestinal hormones, peptides, and amines that can cause maldigestion, diarrhea, steatorrhea, and altered gastrointestinal motility. Patients with carcinoid syndrome are at risk of malnutrition due to tryptophan depletion, reduced intake of food, and loss of appetite because of diarrhea and/or flushing. To date, there is limited information on the nutritional issues faced by patients with neuroendocrine tumors, and on what specific recommendations should be made to patients concerning nutrition at various stages of the disease process. Dietary planning should therefore be an integral part of multidisciplinary management for patients with neuroendocrine tumors. Herein, we review current guidance for nutrition in patients with neuroendocrine tumors, focusing on intake of amines and foods to avoid, as well as concurrent medications. We also propose a new and practical food pyramid based on the principles of Mediterranean diet 4.0 that can be easily adapted according to the unmet needs of patients with neuroendocrine tumors at all stages of disease. The overarching goal of the present review is to create greater awareness of nutritional care and considerations that should be given to patients with neuroendocrine tumors.

Limited Diagnostic Utility of Chromogranin A Measurements in Workup of Neuroendocrine Tumors

BACKGROUND

Plasma chromogranin A (CgA) is related to tumor burden and recommended in the follow-up of patients diagnosed with neuroendocrine tumors (NETs). The use of CgA in the workup of a suspected NET is more questionable.

OBJECTIVE

To assess the positive predictive value (PPV) of CgA plasma concentrations above the upper reference limit (URL) in patients with suspected NET.

METHOD

Patients referred to the NET Centre, Rigshospitalet, Copenhagen from 2015 to 2019 with clinically suspected NET were included if a CgA measurement was performed prior to referral. The utility of CgA was assessed by comparing pre-referral CgA concentrations to the outcome of a thorough workup. In 47 selected cases with continuously unexplained elevated CgA concentrations, a processing-independent analysis (PIA) for CgA was performed.

RESULTS

A total of 197 patients were included. NET was ultimately diagnosed in 25 patients. CgA plasma concentrations were above the URL (elevated) in 19/25 patients diagnosed with NET. In total, 167/197 had elevated CgA concentrations at referral. The positive predictive value (PPV) of elevated CgA concentration was 11% (19/167). Proton pump inhibitor (PPI) treatment was identified as the possible cause of CgA elevation in 55/148 patients with falsely elevated CgA. CgA concentration was normal in 28/47 patients when using PIA.

CONCLUSION

Our data do not support using measurement of CgA for screening when NET is suspected since the PPV was rather low. PPI treatment is a common cause of increased CgA concentrations and should always be discontinued before CgA measurement. PIA of CgA could be a way of excluding NET when suspicion is based primarily on elevated CgA.

Surgery and Perioperative Management in Small Intestinal Neuroendocrine Tumors

Small-intestinal neuroendocrine tumors (SI-NETs) are the most prevalent small bowel neoplasms with an increasing frequency. In the multimodal management of SI-NETs, surgery plays a key role, either in curative intent, even if R0 resection is feasible in only 20% of patients due to advanced stage at diagnosis, or palliative intent. Surgeons must be informed about the specific surgical management of SI-NETs according to their hormonal secretion, their usual dissemination at the time of diagnosis and the need for bowel-preserving surgery to avoid short bowel syndrome. The aim of this paper is to review the surgical indications and techniques, and perioperative and postoperative management of SI-NETs.

Pathogenesis and Clinical Management of Mesenteric Fibrosis in Small Intestinal Neuroendocine Neoplasms: A Systematic Review

Mesenteric fibrosis (MF) constitutes an underrecognized sequela in patients with small intestinal neuroendocrine neoplasms (SI-NENs), often complicating the disease clinical course. The aim of the present systematic review, carried out by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, is to provide an update in evolving aspects of MF pathogenesis and its clinical management in SI-NENs. Complex and dynamic interactions are present in the microenvironment of tumor deposits in the mesentery. Serotonin, as well as the signaling pathways of certain growth factors play a pivotal, yet not fully elucidated role in the pathogenesis of MF. Clinically, MF often results in significant morbidity by causing either acute complications, such as intestinal obstruction and/or acute ischemia or more chronic conditions involving abdominal pain, venous stasis, malabsorption and malnutrition. Surgical resection in patients with locoregional disease only or symptomatic distant stage disease, as well as palliative minimally invasive interventions in advanced inoperable cases seem clinically meaningful, whereas currently available systemic and/or targeted treatments do not unequivocally affect the development of MF in SI-NENs. Increased awareness and improved understanding of the molecular pathogenesis of MF in SI-NENs may provide better diagnostic and predictive tools for its timely recognition and intervention and also facilitates the development of agents targeting MF.

Interventional Liver-Directed Therapy for Neuroendocrine Metastases: Current Status and Future Directions

OPINION STATEMENT

Liver-directed therapy should be considered for patients with unresectable liver metastases from neuroendocrine tumor if symptomatic or progressing despite medical management. Our experience and current literature shows that the bland embolization, chemoembolization, and radioembolization are very effective in controlling symptoms and disease burden in the liver, and that these embolization modalities are similar in terms of efficacy and radiologic response. Their safety profiles differ, however, with recent studies suggesting an increase in biliary toxicity with drug-eluting bead chemoembolization over conventional chemoembolization, and a risk of long-term hepatotoxicity with radioembolization. For this reason, we tailor the type of embolotherapy to each patient according to their clinical status, symptoms, degree of tumor burden, histologic grade, and life expectancy. We do not recommend a "one-size-fits-all" approach. Our general strategy is to use bland embolization as first-line embolotherapy, and radioembolization for patients with high-grade tumors or who have failed other embolotherapy.

Carcinoid Syndrome: A Review

Carcinoid syndrome (CS) is a paraneoplastic syndrome caused by the release of serotonin and other substances from well-differentiated neuroendocrine tumors (NETs). The hallmark symptoms of carcinoid syndrome are flushing and diarrhea; atypical signs and symptoms can include wheezing, abdominal pain, valvular heart disease, telangiectasias, pellagra, and the complications of mesenteric fibrosis, including ureteral obstruction, bowel obstruction, and bowel ischemia. These symptoms are mediated by the release of serotonin (5-HT), histamine, kallikrein, prostaglandins, and tachykinins. The diagnosis of CS requires these symptoms and corresponding elevations in lab tests. Treatment options include surgery and medical management with somatostatin analogs.

An unusual case of proton pump inhibitor induced hyperchromograninemia

Objective: To describe an unusual case of symptomatic hyperchromograninemia associated with proton pump inhibitor (PPI) use.

Case Summary: A 55-year-old man with stage 1 follicular lymphoma and GERD on omeprazole presented with symptoms suggesting carcinoid syndrome. The only positive finding on workup was a markedly elevated level of chromogranin A and no carcinoid tumor was identified. Omeprazole was discontinued, following which his symptoms resolved and chromogranin A levels returned to normal. To the best of our knowledge, no symptoms have been previously reported in association with PPI-induced hyperchromograninemia.

Discussion: The reliability of chromogranin A as a marker for neuroendocrine tumors is of growing concern. The reasons for the associated symptomatology in this case are unclear but could involve physiologic effects of chromogranin A breakdown products. The role of pharmacogenomics in PPI metabolism is discussed as a potential explanation for the significant hyperchromograninemia.

Conclusion: The phenomenon of PPI-induced hyperchromograninemia is highlighted for providers especially in the context of neuroendocrine tumor diagnosis and surveillance. The need for more research into chromogranins is proposed.

Update on Pathophysiology, Treatment, and Complications of Carcinoid Syndrome

Carcinoid syndrome (CS) develops in patients with hormone-producing neuroendocrine neoplasms (NENs) when hormones reach a significant level in the systemic circulation. The classical symptoms of carcinoid syndrome are flushing, diarrhoea, abdominal pain, and wheezing. Neuroendocrine neoplasms can produce multiple hormones: 5-hydroxytryptamine (serotonin) is the most well-known one, but histamine, catecholamines, and brady/tachykinins are also released. Serotonin overproduction can lead to symptoms and also stimulates fibrosis formation which can result in development of carcinoid syndrome-associated complications such as carcinoid heart disease (CaHD) and mesenteric fibrosis. Transforming growth factor beta (TGF-β) is one of the main factors in developing fibrosis, but platelet-derived growth factor (PDGF), basic fibroblast growth factor (FGF2), and connective tissue growth factor (CTGF or CCN2) are also related to fibrosis development. Treatment of CS focuses on reducing serotonin levels with somatostatin analogues (SSA's). Telotristat ethyl and peptide receptor radionuclide therapy (PRRT) have recently become available for patients with symptoms despite being established on SSA's. Screening for CaHD is advised, and early intervention prolongs survival. Mesenteric fibrosis is often present and associated with poorer survival, but the role for prophylactic surgery of this is unclear. Depression, anxiety, and cognitive impairment are frequently present symptoms in patients with CS but not always part of their care plan. The role of antidepressants, mainly SSRIs, is debatable, but recent retrospective studies show evidence for safe use in patients with CS. Carcinoid crisis is a life-threatening complication of CS which can appear spontaneously but mostly described during surgery, anaesthesia, chemotherapy, PRRT, and radiological procedures and may be prevented by octreotide administration.

Management of Gastrointestinal Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are derived from neuroendocrine cell system and can have benign or malignant characteristics. They are rare tumors, but have been increasing in incidence over the past 40 years. Patients with NENs may develop symptoms due to primary tumor invasion, metastasis, or from secretion of hormonally active tumor substances. Multiple imaging modalities are used for diagnosis and staging, including specialty scans such as ¹¹¹In pentetreotide (Octreoscan) and ⁶⁸Gallium-DOTATATE, along with endoscopy, endoscopic ultrasound, and biochemical marker testing. Treatment involves both surgical approach, for both primary and metastatic lesions, as well as medical management for symptom management and disease progression. This article will review the current clinical knowledge regarding the diagnosis, treatment, and prognosis of these fascinating neoplasms and the associated hormonal syndromes.

Targeted Systemic Treatment of Neuroendocrine Tumors: Current Options and Future Perspectives

Neuroendocrine tumors (NETs) originate from the neuroendocrine cell system in the bronchial and gastrointestinal tract and can produce hormones leading to distinct clinical syndromes. Systemic treatment of patients with unresectable NETs aims to control symptoms related to hormonal overproduction and tumor growth. In the last decades prognosis has improved as a result of increased detection of early stage disease and the introduction of somatostatin analogs (SSAs) as well as several new therapeutic options. SSAs are the first-line medical treatment of NETs and can control hormonal production and tumor growth. The development of next-generation multireceptor targeted and radiolabelled somatostatin analogs, as well as target-directed therapies (as second-line treatment options) further improve progression-free survival in NET patients. To date, however, a significant prolongation of overall survival with systemic treatment in NET has not been convincingly demonstrated. Several new medical options and treatment combinations will become available in the upcoming years, and although preliminary results of preclinical and clinical trials are encouraging, large, preferrably randomized clinical studies are required to provide definitive evidence of their effect on survival and symptom control.

Spotlight on telotristat ethyl for the treatment of carcinoid syndrome diarrhea: patient selection and reported outcomes

Neuroendocrine tumors (NETs) are rare cancers with an associated prolonged survival in some patients. A proportion of patients diagnosed with NETs will present with carcinoid syndrome symptoms, characterized by diarrhea, flushing and/or wheezing. This review summarizes the current treatment options for carcinoid syndrome, focusing on the latest novel treatment option, telotristat ethyl. In addition, information on patient-reported outcomes and impact of carcinoid syndrome on quality of life (QOL) and improvement of following treatment with telotristat ethyl are reviewed. This article also provides an overview of the current QOL questionnaires for patients with NETs and addresses unmet needs in this field of patient-reported outcomes.

Long-Term Safety Experience with Telotristat Ethyl Across Five Clinical Studies in Patients with Carcinoid Syndrome

BACKGROUND

Patients with neuroendocrine tumors (NETs) and carcinoid syndrome experience considerable morbidity and mortality; carcinoid syndrome may be associated with shorter survival. Carcinoid syndrome is linked to tumoral secretion of serotonin and other bioactive substances. The subsequent debilitating diarrhea and urgency to defecate pose significant health risks. In previous studies, telotristat ethyl, a tryptophan hydroxylase inhibitor, was effective and well tolerated in treating carcinoid syndrome diarrhea. We present pooled safety data from five clinical trials with telotristat ethyl in patients with carcinoid syndrome.

SUBJECTS, MATERIALS, AND METHODS

Adverse events reported during telotristat ethyl treatment were pooled from two phase II and three phase III clinical trials in 239 patients with carcinoid syndrome. Long-term safety of telotristat ethyl and causes of hospitalization and death were reviewed; overall survival was estimated.

RESULTS

Mean (median; range) duration of exposure and follow-up was 1.3 years (1.1 years; 1 week to 5.7 years), with 309 total patient-years of exposure. Leading causes of hospitalization were gastrointestinal disorders or were related to the underlying tumor and related treatment. Survival estimates at 1, 2, and 3 years were 93%, 88%, and 77%. Nearly all deaths were due to progression or complication of the underlying disease; none were attributable to telotristat ethyl. There was one death in year 4.

CONCLUSION

Based on long-term safety data, telotristat ethyl is well tolerated and has a favorable long-term safety profile in patients with carcinoid syndrome.

IMPLICATIONS FOR PRACTICE

Carcinoid syndrome can cause persistent diarrhea, even in patients treated with somatostatin analogs. Across five clinical trials in patients with carcinoid syndrome, telotristat ethyl has been well tolerated and efficacious, providing clinicians with a new approach to help control carcinoid syndrome diarrhea, in addition to somatostatin analog therapy. By reducing the stool frequency in patients with carcinoid syndrome whose diarrhea is refractory to anticholinergics, such as loperamide and atropine/diphenoxylate, and somatostatin analog dose escalation, improvement in quality of life becomes an achievable goal.

Mechanisms of cardiac collagen deposition in experimental models and human disease

The inappropriate deposition of extracellular matrix within the heart (termed cardiac fibrosis) is associated with nearly all types of heart disease, including ischemic, hypertensive, diabetic, and valvular. This alteration in the composition of the myocardium can physically limit cardiomyocyte contractility and relaxation, impede electrical conductivity, and hamper regional nutrient diffusion. Fibrosis can be grossly divided into 2 types, namely reparative (where collagen deposition replaces damaged myocardium) and reactive (where typically diffuse collagen deposition occurs without myocardial damage). Despite the widespread association of fibrosis with heart disease and general understanding of its negative impact on heart physiology, it is still not clear when collagen deposition becomes pathologic and translates into disease symptoms. In this review, we have summarized the current knowledge of cardiac fibrosis in human patients and experimental animal models, discussing the mechanisms that have been deduced from the latter in relation to the former. Because assessment of the extent of fibrosis is paramount both as a research tool to further understanding and as a clinical tool to assess patients, we have also summarized the current state of noninvasive/minimally invasive detection systems for cardiac fibrosis. Albeit not exhaustive, our aim is to provide an overview of the current understanding of cardiac fibrosis, both clinically and experimentally.

Efficacy of Detoxsan® powder on diarrhea caused by gastrointestinal neuroendocrine tumors

BACKGROUND

Patients with neuroendocrine tumors (NETs) of the gastrointestinal tract suffer frequently from chronic diarrhea. A well characterized medical advice containing zeolite (Detoxsan^® powder) was applied to patients suffered from therapy-refractory diarrhea either by its frequency or by watery stool, despite receiving standard pharmacotherapy according to the guidelines for carcinoid syndrome and comorbidities. Detoxsan^® powder acts as an adsorbent and might reduce significantly symptoms of diarrhea in patients suffering from NETs.

AIM

To overcome the therapy-refractory diarrhea of patients with NETs by the zeolite containing medical advice Detoxsan^® powder.

METHODS

A total of 20 patients (12 female and 8 male) suffering from diarrhea either by its frequency or from watery stool caused by NETs were included. In each patient, the diagnosis had been confirmed by histology and somatostatin receptors expression proven by positron emission tomography/computed tomography using Ga-68-labeled somatostatin analogs. All patients received standard-of-care pharmacotherapy and were additionally given Detoxsan^® powder as an extemporaneous drug containing 90% natural Cuban zeolite and 10% magnesium aspartate. Recommended daily dosage ranges between 3 g once to three times per day. Each day dose and bowel movements were documented by the patients themselves in a pre-defined table. Additionally to the bowel movements quantitative determinations of serotonin, urea, creatinine and single ions were performed within the serum of the patients by commercially available equipment used as a matter of routine in the clinic.

RESULTS

All patients enrolled in this pilot study did not only suffer from NETs, but also from comorbidities and treatment-resistant diarrhea. There was insufficient control of diarrhea, most probably due to the secretion of hormones like serotonin produced by the slowly growing and highly differentiated NETs. All patients only took Detoxsan^® powder as an antidiarrheal drug. In general, response effects need several days to become perceptible and require an intake of Detoxsan^® powder for an extended time period or intermittently, if persisting stabilization of bowel movements could not be achieved. A correlation between NET grade, part and size of bowel resection and functionality of the tumor could not be demonstrated. Therefore, diarrhea seemed to be based on the metabolic activity of the well-differentiated NETs, which eventually led to treatment resistance. In summary, 14 out of the 20 patients (70%) declared to be very content with using Detoxsan^® powder and observed a significant reduction of diarrhea, while the effective dose and intake period that resulted in a symptom relief varied individually.

CONCLUSION

Detoxsan^® powder is able to reduce significantly symptoms of NET-related diarrhea in the majority of patients. The duration of taking Detoxsan^® powder and its dosage vary individually.

Carcinoid Heart Disease and Decreased Overall Survival among Patients with Neuroendocrine Tumors: A Retrospective Multicenter Latin American Cohort Study

The background to this study was that factors associated with carcinoid heart disease (CHD) and its impacts on overall survival (OS) are scantly investigated in patients (pts) with neuroendocrine tumors (NETs). In terms of materials and methods, a retrospective multicenter cohort study was conducted of factors associated with CHD in advanced NET pts with carcinoid syndrome (CS) and/or elevated urinary 5-hidroxyindole acetic acid (u5HIAA). CHD was defined as at least moderate right valve alterations. The results were the following: Among the 139 subjects included, the majority had a midgut NET (54.2%), 81.3% had CS, and 93% received somatostatin analogues. In a median follow-up of 39 months, 48 (34.5%) pts developed CHD, with a higher frequency in pts treated in public (77.2%) versus private settings (22.9%). In a multivariate logistic regression, unknown primary or colorectal NETs (Odds Ratio (OR) 4.35; p = 0.002), at least 50% liver involvement (OR 3.45; p = 0.005), and being treated in public settings (OR 4.76; p = 0.001) were associated with CHD. In a Cox multivariate regression, bone metastases (Hazard Ratio {HR} 2.8; p = 0.031), CHD (HR 2.63; p = 0.038), and a resection of the primary tumor (HR 0.33; p = 0.026) influenced the risk of death. The conclusions were the following: The incidence of CHD was higher in pts with a high hepatic tumor burden and in those treated in a public system. Delayed diagnosis and limited access to effective therapies negatively affected the lives of NET patients.

Mixed neuroendocrine-non-neuroendocrine carcinoma of gallbladder: case report

Background

Mixed neuroendocrine-non-neuroendocrine tumors (MINEN) of the gallbladder are extremely rare; indeed, the English expert literature reports a mere handful of case reports and case series on this topic. According to the WHO classification of 2010, MINEN are considered to be tumors consisting of two major components, neuroendocrine and non-neuroendocrine, each of which hosts at least 30% of the total cellular population. To date, the etiology and pathogenesis of MINEN have not been precisely determined and the non-specific symptoms generally result in late diagnosis (mainly in the terminal stages of the condition) and contribute to the generally poor prognosis. As far as the management of the disease is concerned, radical surgery plays a crucial role; however, the significance of surgical debulking and biological therapy applying somatostatin analogues has not yet been determined.

Case presentation

A 56-year-old female was referred to our department for a rapidly progressing tumor in the subhepatic area along with the infiltration of S5 and S6 liver segments. With regard to preoperative findings, the tumor appeared as operable, although, during the surgery, an extensive involvement of the hepatoduodenal ligament by the tumor through the lymph nodes was revealed. Due to acute perioperative bleeding from the necrotic tumor, we decided to perform modified resection. Histologically, the tumor was confirmed as MINEN of gallbladder, where the neuroendocrine component was dominant over the non-neuroendocrine component. Six weeks after the discharge, the patient underwent a follow-up CT revealing large recurrence of the disease. Thereafter, the patient was started on systemic therapy with etoposide and carboplatin in combination with somatostatin analogues. Thirteen months after the surgery, the patient is in good clinical condition, and while a recently performed PET/MRI scan revealed a hepatic lesion and hilar lymphadenopathy in full regression, there was a spread of small peritoneal and pleural metastases. The patient remains in the follow-up care.

Conclusions

The occurrence of mixed neuroendocrine-non-neuroendocrine neoplasms is extremely rare. Radical surgery remains the only potentially effective approach to the cure of this disease. The role of biological therapy and debulking in the management of the disease has not yet been precisely defined. In our experience, both of these methods have the potential to positively influence overall survival rates and the postoperational quality of life of patients.

High tumour burden, delayed diagnosis and history of cardiovascular disease may be associated with carcinoid heart disease

Background

Patients with carcinoid syndrome (CS) may present carcinoid heart disease (CHD) but prognostic factors are not entirely understood.

Patients and Methods

Retrospective study of patients with metastatic neuroendocrine tumours (NETs) and CS and/or abnormal 24-hour-urinary 5-hydroxiindolacetic acid. CHD was defined as moderate to severe tricuspid or pulmonary regurgitation in the echocardiogram.

Results

The frequency of CHD among 42 patients was 38% (95% confidence interval [CI]: 23%-54%). CHD was associated with higher volume of liver metastases (odds ratio [OR] 13.86, 95% CI: 2.57-74.68, p = 0.002). Time from CS symptoms to NET diagnosis was borderline significant (p = 0.08). When CHD was defined as at least mild tricuspide regurgitation, the frequency of CHD was 45% and it was associated with cardiovascular comorbidities (OR: 6.58, 95% CI: 1.09; 39.78, p = 0.040).

Conclusion

CHD was frequent among patients with CS, significantly associated with high liver tumour burden, and likely linked to the history of cardiovascular disease and longer time of CS.

New Treatments for the Carcinoid Syndrome

Neuroendocrine tumors, including carcinoids, are rare and insidiously growing tumors. Related to their site of origin, tumors can be functional, causing various forms of the carcinoid syndrome, owing to the overproduction of serotonin, histamine, or other bioactive substances. They often invade adjacent structures or metastasize to the liver and elsewhere. Treatment includes multimodal approaches, including cytoreductive surgery, locoregional embolization, cytotoxic therapy, peptide receptor radionuclide therapy, and various targeted therapies with goals of symptom relief and control of tumor growth. This article summarizes current and emerging approaches to management and reviews several promising future therapies.

Carcinoid syndrome: update on the pathophysiology and treatment

Approximately 30-40% of patients with well-differentiated neuroendocrine tumors present with carcinoid syndrome, which is a paraneoplastic syndrome associated with the secretion of several humoral factors. Carcinoid syndrome significantly and negatively affects patients' quality of life; increases costs compared with the costs of nonfunctioning neuroendocrine tumors; and results in changes in patients' lifestyle, such as diet, work, physical activity and social life. For several decades, patients with neuroendocrine tumors and carcinoid syndrome have been treated with somatostatin analogues as the first-line treatment. While these agents provide significant relief from carcinoid syndrome symptoms, there is inevitable clinical progression, and new therapeutic interventions are needed. More than 40 substances have been identified as being potentially related to carcinoid syndrome; however, their individual contributions in triggering different carcinoid symptoms or complications, such as carcinoid heart disease, remain unclear. These substances include serotonin (5-HT), which appears to be the primary marker associated with the syndrome, as well as histamine, kallikrein, prostaglandins, and tachykinins. Given the complexity involving the origin, diagnosis and management of patients with carcinoid syndrome, we have undertaken a comprehensive review to update information about the pathophysiology, diagnostic tools and treatment sequence of this syndrome, which currently comprises a multidisciplinary approach.