Carcinoid heart disease: relationship of circulating vasoactive substances to ultrasound-detectable cardiac abnormalities

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.

What Is Carcinoid Syndrome? A Critical Appraisal of Its Proposed Mediators

Carcinoid syndrome (CS) is a debilitating disease that affects approximately 20% of patients with neuroendocrine neoplasms (NEN). Due to the increasing incidence and improved overall survival of patients with NEN over recent decades, patients are increasingly suffering from chronic and refractory CS symptoms. At present, symptom control is hampered by an incomplete understanding of the pathophysiology of this syndrome. This systematic review is the first to critically appraise the available evidence for the various hormonal mediators considered to play a causative role in CS. Overall, evidence for the putative mediators of CS was scarce and often of poor quality. Based on the available literature, data are only sufficient to agree on the role of serotonin as a mediator of CS-associated diarrhea and fibrosis. A direct role for tachykinins and an indirect role of catecholamines in the pathogenesis of CS is suggested by several studies. Currently, there is insufficient evidence to link histamine, bradykinin, kallikrein, prostaglandins, or motilin to CS. To summarize, available literature only sufficiently appoints serotonin and suggests a role for tachykinins and catecholamines as mediators of CS, with insufficient evidence for other putative mediators. Descriptions of CS should be revised to focus on these proven hormonal associations to be more accurate, and further research is needed into other potential mediators.

Carcinoid Heart Syndrome With Metastatic Low-Grade Neuroendocrine Tumor of the Liver: A Rare Case

We present a rare and complex case of a 76-year-old male patient with a history of low-grade neuroendocrine tumor (NET) of the small intestine, status post resection, who presented with recurrence of the tumor in the liver and subsequent carcinoid heart syndrome (CHS). The recurrent liver tumor caused severe tricuspid regurgitation and CHS, highlighting the rare association between NETs and CHS, particularly in the elderly population. This case underscores the importance of multidisciplinary care and close monitoring for patients with recurrent NETs and potential cardiac complications.

Prevalence, one-year-incidence and predictors of carcinoid heart disease

BACKGROUND

Carcinoid heart disease (CHD) caused by neuroendocrine tumours (NET) is associated with an increased morbidity and mortality due to valvular dysfunction and right sided heart failure. The present study aimed to assess the prevalence and one-year-incidence of CHD in NET patients. Tumour characteristics, laboratory measurements, and echocardiographic findings were evaluated to identify predictors of CHD manifestation.

METHODS

The study was an investigator-initiated, monocentric, prospective trial. Patients with NET without previously diagnosed CHD were included and underwent comprehensive gastroenterological and oncological diagnostics. Echocardiographic examinations were performed at baseline and after one year.

RESULTS

Forty-seven NET patients were enrolled into the study, 64% of them showed clinical features of a carcinoid syndrome (CS). Three patients presented with CHD at baseline and three patients developed cardiac involvement during the follow-up period corresponding to a prevalence of 6% at baseline and an incidence of 6.8% within one year. Hydroxyindoleacetic acid (5-HIAA) was identified to predict the occurrence of CHD (OR, 1.004; 95% CI, 1.001-1.006 for increase of 5-HIAA), while chromogranin A (CgA), and Kiel antigen 67 (Ki 67%) had no predictive value. Six patients with CHD at twelve-month follow-up revealed a tendency for larger right heart diameters and increased values of myocardial performance index (MPEI) at baseline compared to NET patients.

CONCLUSION

The prevalence at baseline and one-year-incidence of CHD was 6-7%. 5-HIAA was identified as the only marker which predict the development of CHD.

The Past, Present, and The Future of Carcinoid Heart Disease

Carcinoid heart disease is a frequent manifestation of carcinoid syndrome. It results from the release of a large amount of serotonin and subsequently fibrosis of right sided heart valves, that is, tricuspid and pulmonic valve. This article reviews the pathogenesis, clinical symptoms, diagnosis, treatment and prognosis of carcinoid heart disease. Recent developments in treating carcinoid heart disease have improved the poor prognosis associated with the disease.

Carcinoid Heart Disease Management: A Multi-Disciplinary Collaboration

Carcinoid heart disease (CaHD) is an important complication among patients with metastatic neuroendocrine tumors and carcinoid syndrome (CS). CS patients (25%-65%) eventually develop CaHD; these patients face a significantly increased risk of morbidity and mortality. Guidance papers (eg, clinical practice guidelines, consensus guidelines, and expert statements) have been established by major organizations across the disciplines of cardiology and oncology; however, these recommendations are not routinely implemented. The aim of this article is to encourage the integration of current recommendations from national societies into clinical practice. Early screening upon recognition of CS and prior to the development of CaHD symptoms is paramount, as no existing therapies are approved to reverse the fibrotic damage to the heart once it occurs. Valvular replacement is the only definitive treatment for CaHD once it has developed. When patients are noted to have urinary 5-hydroxyindoleacetic acid (5-HIAA) levels ≥300 µmol/24 h and/or serum N-terminal pro B-type natriuretic peptide (NT-proBNP) levels >260 pg/mL, echocardiography is recommended. Systemic approaches to control tumor growth and hormonal secretion include somatostatin analogs (SSAs), followed by options including peptide receptor radiotherapy (PRRT), everolimus and liver embolization. Telotristat is the primary choice for control of diarrhea refractory to SSA. Diuretics are the mainstay of heart failure symptom management for patients who develop CaHD. Considerations for future research are discussed, including the ongoing TELEHEART (TELotristat Ethyl in a HEART biomarker study) trial involving telotristat and not yet activated CHARRT (Carcinoid Heart disease And peptide Receptor Radiotargetted Therapy) study involving PRRT with lutetium 177 (177Lu) dotatate.

Outcome of carcinoid heart syndrome in patients enrolled in the SwissNet cohort

BACKGROUND

Carcinoid heart disease is a rare disease which develops in patients with functional neuroendocrine tumors in an advanced tumor state. Patients diagnosed with carcinoid heart disease have a poor longtime prognosis with respect to morbidity and mortality and long-term data on patient outcomes are lacking.

METHODS AND RESULTS

In this retrospective study, we analyzed outcomes of 23 patients with carcinoid heart disease enrolled into the SwissNet database. We observed that early diagnosis with echocardiographic surveillance of carcinoid heart disease during the course of the neuroendocrine tumor disease was beneficial to overall survival of patients.

CONCLUSION

Through nationwide patient enrollment, the SwissNet registry is a powerful data tool to identify, follow-up and evaluate long-term patient outcomes in patients with rare neuroendocrine tumor driven pathologies including carcinoid heart syndrome with observational methods enabling better therapy optimization to improve patient`s long-term perspectives and survival. In line with the current ESMO recommendations, our data proposes that heart echocardiography should be included as part of the general physical assessment in patients with newly diagnosed NET.

Heterotopic Transcatheter Tricuspid Valve Replacement in a Patient With Carcinoid Heart Disease

Neuroendocrine tumors can lead to carcinoid heart disease with subsequent development of severe tricuspid regurgitation due to thickening and restriction of the tricuspid leaflets. We present a patient who underwent successful heterotopic transcatheter tricuspid valve replacement for torrential tricuspid regurgitation due to carcinoid heart disease. (Level of Difficulty: Intermediate.)

Mechanism and prevention strategy of a bidirectional relationship between heart failure and cancer (Review)

The relationship between cancer and heart failure has been extensively studied in the last decade. These studies have focused on describing heart injury caused by certain cancer treatments, including radiotherapy, chemotherapy and targeted therapy. Previous studies have demonstrated a higher incidence of cancer in patients with heart failure. Heart failure enhances an over-activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, and subsequently promotes cancer development. Other studies have found that heart failure and cancer both have a common pathological origin, flanked by chronic inflammation in certain organs. The present review aims to summarize and describe the recent discoveries, suggested mechanisms and relationships between heart failure and cancer. The current review provides more ideas on clinical prevention strategies according to the pathological mechanism involved.

Update in carcinoid heart disease - the heart of the matter

Carcinoid heart disease (CHD) is a paraneoplastic cardiac manifestation occurring in patients with carcinoid syndrome (CS) and advanced neuroendocrine malignancy. In about 20-40% of patients with CS, chronic exposure to tumor-released circulating vasoactive peptides typically results in right-sided valvular fibrosis leading to valve dysfunction and right heart failure. CHD remains a significant cause of morbidity and mortality. The management of patients with CHD is complex, as both the systemic malignant disease and the heart involvement have to be addressed. Early diagnosis and timely surgical intervention in selected patients are of utmost importance and offer a survival benefit. In patients with advanced carcinoid heart disease, valve replacement surgery is the most effective option to alleviate cardiac symptoms and contribute to survival outcomes. A collaboration of a multidisciplinary team in centers with experience is required to provide optimal patient management. Here, we review the current literature regarding CHD presentation, pathophysiology, diagnostic tools, and available treatment strategies.

Outcomes and periprocedural management of cardiac implantable electronic devices in patients with carcinoid heart disease

BACKGROUND

Carcinoid heart disease (CHD) is a rare complication of hormonally active neuroendocrine tumors that often requires surgical intervention. Data on cardiac implantable electronic device (CIED) implantation in patients with CHD are limited.

OBJECTIVE

The purpose of this study was to evaluate the experience of CIED implantation in patients with CHD.

METHODS

Patients with a diagnosis of CHD and a CIED procedure from January 1, 1995, through June 1, 2020, were identified using a Mayo Clinic proprietary data retrieval tool. Retrospective review was performed to extract relevant data, which included indications for implant, procedural details, complications, and mortality.

RESULTS

A total of 27 patients (55.6% male; mean age at device implant 65.6 ± 8.8 years) with cumulative follow-up of 75 patient-years (median 1.1 years; interquartile range 0.4-4.6 years) were included for analysis. The majority of implanted devices were dual-chamber permanent pacemakers (63%). Among all CHD patients who underwent any cardiac surgery, the incidence of CIED implantation was 12%. The most common indication for implantation was high-grade heart block (66.7%). Device implant complication rates were modest (14.8%). No patient suffered carcinoid crisis during implantation, and there was no periimplant mortality. Median time from implant to death was 2.5 years, with 1-year mortality of 15%.

CONCLUSION

CHD is a morbid condition, and surgical valve intervention carries associated risks, particularly a high requirement for postoperative pacing needs. Our data suggest that CIED implantation can be performed relatively safely. Clinicians must be aware of the relevant carcinoid physiology and take appropriate precautions to mitigate risks.

A 33-year follow-up after valvular surgery for carcinoid heart disease

AIMS

Valvular surgery has improved long-term prognosis in severe carcinoid heart disease (CaHD). Experience is limited and uncertainty remains about predictors for survival and strategy regarding single vs. double-valve surgery. The aim was to review survival and echocardiographic findings after valvular surgery for CaHD at our institution.

METHODS AND RESULTS

Between 1986 and 2019, 60 consecutive patients, median age 64 years, underwent valve surgery for severe CaHD. Operations involved combined tricuspid valve replacement (TVR) and pulmonary valve replacement (PVR) in 42 cases, and TVR-only or TVR with pulmonary valvotomy (no PVR) in 18 patients. All implanted valves were bioprosthetic. Preoperative echocardiography, creatinine, NT-pro-brain natriuretic peptide (NT-pro-BNP), and 24-h urinary 5-hydroxyindoleacetic acid (5-HIAA) were obtained. 30-Day mortality was 12% (n=7), and 8% for the most recent decade 2010-2019. Median survival was 2.2 years and maximum survival 21 years. Patients undergoing combined TVR and PVR had significantly higher survival compared with operations without PVR (median 3.0 vs. 0.9 years, P = 0.02). Preoperative levels of NT-pro-BNP and 5-HIAA in the top quartile predicted poor survival. On preoperative echocardiograms, pulmonary regurgitation was severe in 51% and indeterminate in 17%. Postoperative echocardiography confirmed relatively good durability of bioprostheses, relative to the patients' limited oncological life expectancy.

CONCLUSION

Valvular surgery in CaHD has an acceptable perioperative risk. Survival for combined TVR and PVR was significantly higher compared with operations without PVR. Bioprosthetic valve replacement appears to have adequate durability. Preoperative echocardiography may underestimate pulmonary pathology. Combined TVR and PVR should be considered in most patients.

Vigilance for carcinoid heart disease is still required in the era of somatostatin analogues: Lessons from a case series

AIM

Carcinoid heart disease (CHD) is a well-documented complication of neuroendocrine tumors (NETs) due to secreted hormones causing fibrosis. Somatostatin analogues (SSAs) can decrease hormonal secretion and inhibit tumor growth. The reported incidence of CHD has decreased as SSA use has increased. We describe a series of patients who have developed CHD even though they were treated with SSA therapy.

METHODS

Nine patients were seen in four centers in Australia and New Zealand. The average duration of follow-up from diagnosis was 39 months.

RESULTS

Three patients had Grade 1 and six Grade 2 disease by World Health Organization 2010 criteria. All patients had no CHD symptoms at baseline and started SSA therapy soon after diagnosis, yet developed significant, symptomatic cardiac dysfunction in their disease course. The median time from NET diagnosis to SSA initiation was 1 month, and median time from NET diagnosis to CHD diagnosis was 23 months (range 4-52). All patients who were tested had persistently increased hormonal levels (chromogranin A, urinary 5-hydroxyindolacetic acid).

CONCLUSIONS

The good symptomatic control afforded by SSAs should not lead to reduced vigilance in screening for CHD, especially in patients with persistently elevated hormonal assays. Clinicians should consider regular echocardiographic screening in patients with a secretory syndrome.

Cardiac Imaging in Carcinoid Heart Disease

Carcinoid disease is caused by neuroendocrine tumors, most often located in the gut, and leads in approximately 20% of cases to specific, severe heart disease, most prominently affecting right-sided valves. If cardiac disease occurs, it determines the patient's prognosis more than local growth of the tumor. Surgical treatment of carcinoid-induced valve disease has been found to improve survival in observational studies. Cardiac imaging is crucial for both diagnosis and management of carcinoid heart disease; in the past, imaging was accomplished largely by echocardiography, but more recently, imaging for carcinoid heart disease has increasingly become multimodal and warrants awareness of the particular diagnostic challenges of this disease. This paper reviews the pathophysiology and manifestations of carcinoid heart disease in light of the different imaging modalities.

Symptom Diaries of Patients with Midgut Neuroendocrine Tumors Treated with 177Lu-DOTATATE

We report the impact of 177Lu DOTATATE treatment on abdominal pain, diarrhea, and flushing, symptoms that patients with advanced midgut neuroendocrine tumors (NETs) often find burdensome. Methods: All patients enrolled in the international randomized phase 3 Neuroendocrine Tumors Therapy (NETTER-1) trial (177Lu-DOTATATE plus standard-dose octreotide long-acting repeatable [LAR], n = 117; high-dose octreotide LAR, n = 114) were asked to record the occurrence of predefined symptoms in a daily diary. Change from baseline in symptom scores (mean number of days with a symptom) was analyzed using a mixed model for repeated measures. Results: Patients (intent-to-treat) who received 177Lu-DOTATATE experienced a significantly greater decline from baseline in symptom scores than patients who received high-dose octreotide LAR. For 177Lu-DOTATATE, the mean decline in days with abdominal pain, diarrhea, and flushing was 4.10, 4.55, and 4.52 days per 4 weeks, respectively, compared with 0.99, 1.44, and 2.54 days for high-dose octreotide LAR. The mean differences were 3.11 days (95% confidence interval, 1.35-4.88; P = 0.0007) for abdominal pain, 3.11 days (1.18-5.04; P = 0.0017) for diarrhea, and 1.98 days (0.08-3.88; P = 0.0413) for flushing, favoring 177Lu-DOTATATE. A positive repeated measures correlation was found between diary-recorded symptom scores and questionnaire-recorded pain, diarrhea, and flushing. Conclusion: In addition to efficacy and quality of life benefits, symptom diaries from NETTER-1 demonstrated that treatment with 177Lu DOTATATE was associated with statistically significant reductions in abdominal pain, diarrhea, and flushing, constituting the core symptoms of patients with progressive midgut NETs, compared with high-dose octreotide LAR, supporting a beneficial effect of 177Lu DOTATATE on HRQoL.

Causes of Death After Neuroendocrine Tumors Diagnosis: A US Population-Based Analysis

OBJECTIVE

In this study, we aimed to determine the cause of death (COD) after the diagnosis of neuroendocrine tumors (NET).

METHODS

We used the Surveillance, Epidemiology and End Results (SEER) Program to review patients diagnosed with NET during 2000 to 2016. Patients were followed until death, and different CODs were determined.

RESULTS

Of 94,399 patients with NETs, 40.9% died during the study period. During the first year of diagnosis, most deaths were from NETs (73%), followed by other cancers (11.2%) and cardiac diseases (4.6%). After more than 10 years, NET deaths decreased to 24.3%, whereas other cancers and cardiac disease became more common. Neuroendocrine tumors were responsible for 42.8%, 63.4%, and 81.2% of deaths in grade I, grade II, and grade III, respectively. For grade I localized NET, other cancers (22.2%) were the most common COD followed by NET (19.7%), whereas in grade 2 localized NET, NET was COD in 31.1% of cases followed by other cancers (22.4%). In metastatic disease, NET was the most common COD regardless of grade.

CONCLUSIONS

For low-grade localized NET, deaths were mostly secondary to non-NET causes. In contrast, NET is responsible for most of deaths in metastatic NET regardless of grade.

Managing carcinoid heart disease in patients with neuroendocrine tumors

Carcinoid heart disease is a complex clinical entity frequently complicating the course of neuroendocrine tumors and carcinoid syndrome and is associated with significant morbidity and mortality. Although the pathogenesis of carcinoid heart disease remains poorly understood, it appears that the exposure to excessive circulating levels of serotonin contribute a key role, triggering a cascade of events that ultimately results in the development of plaque-like material on the endocardial surfaces of the valve leaflets. The occurrence of carcinoid heart disease may initially run an asymptomatic period, followed by the development of symptoms of congestive cardiac failure. The diagnosis of carcinoid heart disease is suspected by raised biomarkers, such as serum NT-pro-BNP and confirmed by imaging modalities, with echocardiogram being the gold standard to date. Carcinoid heart disease treatment remains challenging as in addition to cardiac dysfunction, tumor burden needs to be tackled with, hence requiring a multidisciplinary approach. Therapy comprises watchful waiting during the first initial stages of the disease; medications for heart failure; optimal control of serotonin secretion from the NET with pharmacotherapy, interventional means or even surgical techniques; and, in selected patients, cardiac valve replacement. The current review summarizes the literature on the diagnosis and management of carcinoid heart disease.

The serotonin reuptake transporter is reduced in the epithelium of active Crohn's disease and ulcerative colitis

Serotonin is a highly conserved and ubiquitous signaling molecule involved in a vast variety of biological processes. A majority of serotonin is produced in the gastrointestinal epithelium, where it is suggested to act as a prominent regulatory molecule in the inflammatory bowel diseases (IBDs) Crohn's disease (CD) and ulcerative colitis (UC). Extracellular and circulating serotonin levels are thought to be elevated during intestinal inflammation, but the underlying mechanisms have been poorly understood. The data on human material are limited, contradictory, and in need of further investigation and substantiating. In this study, we show a potent and significant downregulation of the dominant serotonin reuptake transporter (SERT) mRNA (SLC6A4) in the epithelium from active CD ileitis, CD colitis, and UC colitis, compared with healthy controls. The mRNA of tryptophan hydroxylase 1, the rate-limiting enzyme in serotonin synthesis, was unregulated. Immunohistochemistry showed expression of the SERT protein in both the epithelium and the lamina propria and localized the downregulation to the epithelial monolayer. Laser capture microdissection followed by RNA sequencing confirmed downregulation of SLC6A4 in the epithelial monolayer during intestinal inflammation. Patient-derived colon epithelial cell lines (colonoids) incubated with the proinflammatory cytokine tumor necrosis factor alpha (TNF-α) reduced SERT expression. In summary, these results show that intestinal inflammation potently reduces the expression of SERT in both CD and UC and that TNF-α alone is sufficient to induce a similar reduction in colonoids. The reduced serotonin reuptake capacity may contribute to the increased interstitial serotonin level associated with intestinal inflammation.NEW & NOTEWORTHY The serotonin reuptake transporter is potently reduced in inflamed areas of Crohn's ileitis, Crohn's colitis, and ulcerative colitis. The changes are localized to the intestinal epithelium and can be induced by TNF-α. The serotonin synthesis through tryptophan hydroxylase 1 is unchanged. This regulation is suggested as a mechanism underlying the increased extracellular serotonin levels associated with intestinal inflammation.

Catheter Ablation in Patients With Neuroendocrine (Carcinoid) Tumors and Carcinoid Heart Disease: Outcomes, Peri-Procedural Complications, and Management Strategies

OBJECTIVES

This report describes a series of patients with neuroendocrine tumors with or without carcinoid heart disease undergoing catheter ablation at the authors' institution.

BACKGROUND

Neuroendocrine (carcinoid) tumors are a rare form of neoplasm with the potential for systemic vasoactive effects and cardiac valvular involvement. These tumors can create peri-operative management challenges for the electrophysiologist. However, there are few data regarding ablation outcomes, periprocedural complications, and management of these patients.

METHODS

All patients with neuroendocrine tumors undergoing catheter ablation at the Mayo Clinic, Rochester, Minnesota over a 25-year period were retrospectively reviewed. From this cohort, the type of arrhythmias ablated, the recurrence of arrhythmia, perioperative complications, and mortality were reviewed and analyzed.

RESULTS

A total of 17 patients (52.9% male; mean age 62.4 ± 9.3 years) with neuroendocrine tumors underwent catheter ablation during the study period. Primary tumor sites included the gastrointestinal tract (n = 11), lung (n = 4), ovary (n = 1), and lymph node (n = 1). Nine patients had metastatic disease, 5 of whom were on somatostatin analog therapy at the time of ablation. Three patients had active symptoms of carcinoid syndrome at the time of ablation, and 2 of those patients had carcinoid heart disease. Ablations were performed mainly for atrial arrhythmias (76.5%): atrioventricular nodal re-entry tachycardia (n = 7), atrial fibrillation (n = 4), and atrial flutter (n = 2). Four patients underwent ablation of ventricular arrhythmias. During a mean follow-up of 19.2 ± 26.2 months, arrhythmia recurred in 35.3% of patients. Three patients (17.6%) had periprocedural complications: pericardial effusion (n = 1), groin site hematoma (n = 1), and carcinoid crisis (n = 1). No deaths were noted in the peri-operative period.

CONCLUSIONS

In a unique cohort of patients with neuroendocrine tumors, catheter ablation was feasible in patients with or without carcinoid syndrome. Carcinoid crisis may occur during the periprocedural period, which can be life-threatening, and a specified protocol for management is important to mitigate this risk.

Carcinoid Heart Disease: Pathophysiology, Pathology, Clinical Manifestations, and Management

Carcinoid heart disease (CHD) is a rare and potentially lethal manifestation of an advanced carcinoid (neuroendocrine) tumor. The pathophysiology of CHD is related to vasoactive substances secreted by the tumor, of which serotonin is most prominent in the pathophysiology of CHD. Serotonin stimulates fibroblast growth and fibrogenesis, which can lead to cardiac valvular fibrosis. CHD primarily affects right heart valves, causing tricuspid and pulmonic regurgitation and less frequently stenosis of these valves. Left heart valves are usually spared because vasoactive substances such as serotonin are enzymatically inactivated in the lung vasculature. The pathology of CHD is characterized by plaque-like deposition of fibrous tissue on valvular cusps, leaflets, papillary muscles, chordae, and ventricular walls. Symptomatic CHD usually presents between 50 and 70 years of age, initially as dyspnea and fatigue. Echocardiography is the mainstay of imaging and demonstrates thickened right heart valves with limited mobility and regurgitation. Treatment focuses on control of the underlying carcinoid syndrome, targeting subsequent valvular heart disease and managing consequent heart failure. Surgical valve replacement and catheter-directed valve procedures may be effective for selected patients with CHD.

Features of carcinoid heart disease identified by cardiac computed tomography

BACKGROUND

Carcinoid heart disease (HD) is a rare form of valvular heart disease, the features of which have not been fully described by cardiac computed tomography (CT).

METHODS

All patients with carcinoid HD that underwent cardiac CT, either preoperatively or for assessment of coronary arteries, between Apr-2006 and Dec-2019 at the Royal Free Hospital, UK, were reviewed.

RESULTS

Of 32 patients with carcinoid HD, 29 (91%) had heart valve involvement. Abnormalities of the tricuspid and pulmonary valves were present in all patients, affecting all three leaflets in 23/26 (89%) unoperated patients for both valves. The aortic valve was affected in 4/29 (14%) patients and the mitral valve in 5/29 (17%). Left heart valves were affected in 6/29 (21%) patients. One patient (1/29; 3%) had all four valves affected. Severe changes with significant valvular regurgitation were seen in ≥75% of patients with tricuspid, pulmonary, and aortic valve abnormalities. Three patients had carcinoid myocardial metastases (3/32; 9%) and one patient had constrictive pericarditis (1/32; 3%). Ten patients had surgery of whom four (40%) had invasive coronary angiography preoperatively. Ten patients had a patent foramen ovale. Cardiac CT allowed an accurate assessment of damage to different leaflets/cusps, particularly of the pulmonary valve, where visualization with echocardiography was often (3/8; 38%) incomplete.

CONCLUSION

Cardiac CT is a powerful tool for assessment of cardiac valve abnormalities, coronary arteries and the spatial relationship of coronary arteries with myocardial metastasis in patients with carcinoid HD, and should form part of multimodal imaging of this complex pathology.

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.

Clinical Benefits of Telotristat Ethyl in Patients With Neuroendocrine Tumors and Low Bowel Movement Frequency: An Observational Patient-Reported Outcomes Study

OBJECTIVES

We evaluated carcinoid syndrome (CS) symptoms and the real-world effectiveness of telotristat ethyl (TE) among patients with ≤3 bowel movements (BM) per day.

METHODS

Patients with CS initiating TE between March and November 2017 could participate in a nurse support program collecting demographic and CS symptom data before TE initiation (baseline) and during ≥1 monthly follow-up within 3 months. Symptoms for patients averaging ≤3 BM/d at baseline were evaluated using pre/post-Student t tests.

RESULTS

Sixty-eight patients reported ≤3 BM/d at baseline. Symptom burden was high and similar to participants with higher daily BM frequency. After 3 months of TE, most patients reported stable or improved symptoms with significant improvements in urgency (88%; mean [SD], -13.2 [32.2]), stool consistency (88%; -1.3 [2.0]), BMs per day (81%; -0.2 [1.2]), abdominal pain (86%; -13.7 [25.8]), nausea (85%; -30.9 [35.7]), and daily flushing episodes (83%; -1.7 [4.4]; all except BMs per day, P < 0.05).

CONCLUSIONS

This analysis illustrates high CS symptom burden among patients with relatively low daily BM frequency. After initiating TE, patients reported significant improvements in urgency, stool consistency, abdominal pain, nausea, and flushing episodes. Clinicians and population health managers should consider CS symptom burden beyond daily BM frequency when evaluating treatment selection.

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.

Carcinoid Heart Disease: a Comprehensive Review

PURPOSE OF REVIEW

Carcinoid heart disease is a rare disorder that is associated with significant morbidity and mortality. In this review of the literature, we will present current concepts in diagnosis and management of carcinoid heart disease.

RECENT FINDINGS

Recent expert consensus guidelines highlight the role of echocardiography and screening with NT-proBNP for the evaluation of carcinoid heart disease. Advances in medical therapy along with better surgical outcomes highlight the experience and expertise that has been gained in the treatment of carcinoid heart disease. Carcinoid heart disease occurs in patients with neuroendocrine tumors who have carcinoid syndrome. Serotonin appears to play a central role in the development of carcinoid heart disease. Cardiac biomarkers and multimodality imaging can be used to aid in screening and diagnosis. The mainstay of treatment of carcinoid heart disease is surgery.

Hedinger syndrome: first experience and two-year follow-up in patients with carcinoid heart disease

Background

Carcinoid heart disease (CHD) (Hedinger syndrome) is a rare manifestation, it has been described in up to 60% of patients with both neuroendocrine tumors (NETs) and carcinoid syndrome (CS) which, typically inducing right heart-sided abnormalities.

Methods

Between 07/15 and 10/18, six patients (mean age 63±12 years; 3 females) presented with manifested (NYHA III-IV) Hedinger syndrome's related valvular(s) lesion and were operated at our center. Clinical data, adverse events and patient outcomes were recorded.

Results

The tricuspid valve was involved in all patients. Tricuspid valve repair was possible in four patients and two needed replacement. In two patients, operation was performed on beating heart without cross-clamping. Concomitant pulmonary valve replacement in two patients and aortic valve replacement in another two patients. A mean cross-clamp time of 61±50 minutes was observed. One patient with severely impaired right ventricular function needed ECMO support, and died 3 days later due to neuroendocrine enzyme storm. At 13 months, one patient developed severe tricuspid stenosis and underwent re-operation with replacement. Another patient died 18 months after surgery related to the underlying tumour. At mean of 30 months follow-up, four patients were alive and asymptotic.

Conclusions

Hedinger syndrome is a challenging entity in cardiac surgery characterized by aggressive valve lesions combined with metastatic neuroendocrine neoplasia affecting the systemic circulation. We advise a multidisciplinary collaboration to early diagnose cardiac involvement to offer an early and proper treatment regime.

Multimodality imaging in carcinoid heart disease

Neuroendocrine neoplasms arise from the gastrointestinal tract and can lead to carcinoid syndrome. Carcinoid heart disease affects more than half of these patients and is the initial presentation of carcinoid syndrome in up to 20 % of patients. Carcinoid heart disease typically leads to valve dysfunction, but in rare instances, carcinoid tumours can also metastasise to the endocardium and myocardium. Cardiovascular imaging plays an integral role in the diagnosis and prognosis of carcinoid heart disease. The use of multimodality imaging techniques including echocardiography, cardiac MRI, cardiovascular CT and positron emission tomography have allowed for a more comprehensive assessment of carcinoid heart disease. In this review, we discuss the features of carcinoid heart disease observed on multimodality imaging, indications for obtaining imaging studies and their role in carcinoid heart disease management.

Bidirectional Relationship Between Cancer and Heart Failure: Old and New Issues in Cardio-oncology

The main focus of cardio-oncology has been the prevention and treatment of the cardiac toxicity of chemotherapy and radiotherapy. Furthermore, several targeted therapies have been associated with unexpected cardiotoxic side-effects. Recently, epidemiological studies reported a higher incidence of cancer in patients with heart failure (HF) compared with individuals without HF. On this basis, it has been proposed that HF might represent an oncogenic condition. This hypothesis is supported by preclinical studies demonstrating that hyperactivation of the sympathetic nervous system and renin-angiotensin-aldosterone system, which is a hallmark of HF, promotes cancer growth and dissemination. Another intriguing possibility is that the co-occurrence of HF and cancer is promoted by a common pathological milieu characterised by a state of chronic low-grade inflammation, which predisposes to both diseases. In this review, we provide an overview of the mechanisms underlying the bidirectional relationship between HF and cancer.

Serotonin levels and 1-year mortality in patients with neuroendocrine tumors: a systematic review and meta-analysis

Aim: Elevated serotonin in patients with neuroendocrine tumors (NETs) may impact heart failure incidence but a quantitative relationship has not been established. Materials & methods: Systematic review and meta-analysis of studies assessing 24-h urinary 5-hydroxyindoleacetic acid (u5-HIAA) and mortality in patients with NETs (2007-2017) with a primary outcome of 1-year mortality risk and 24-h u5-HIAA. Results: We identified 1715 records of which 12 studies including 755 patients (3442 person-years with 376 deaths) were eligible for meta-analysis. Mean u5-HIAA was 149.2 mg/24 h (standard deviation: 96.6) and mortality was 13.0%. The meta-regression equation showed an 11.8% (95% CI: 8.9-17.0%; I²  = 93.0%) increase in 1-year mortality for every ten-unit increase in u5-HIAA. Conclusion: Serotonin measured by its metabolite u5-HIAA is predictive of 1-year all-cause mortality in patients with NETs.

Carcinoid Heart Disease: Review of Current Knowledge

Carcinoid heart disease is the collective term for all cardiac manifestations in patients who have carcinoid syndrome. Carcinoid heart disease has a multifactorial pathophysiology, and the right side of the heart is usually involved. Symptoms and signs vary depending upon the affected cardiac components; most typical is right-sided heart failure secondary to diseased tricuspid and pulmonary valves. Despite no single ideal diagnostic test, strong suspicion, coupled with serologic and imaging results, usually enables diagnosis. Advances in imaging, such as speckle-tracking echocardiography and cardiac magnetic resonance, have improved the diagnostic yield. Treatment is challenging, warrants a multidisciplinary approach, and can be medical or surgical depending on the cardiac manifestations. Investigators are exploring the therapeutic use of monoclonal antibodies and new somatostatin analogues. In this review, we cover current knowledge about the pathophysiology, diagnosis, and treatment of carcinoid heart disease.

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.

Serotonin contribution to cardiac valve degeneration: new insights for novel therapies?

Heart valve disease (HVD) is a complex entity made by different pathological processes that ultimately lead to the abnormal structure and disorganization of extracellular matrix proteins resulting to dysfunction of the leaflets. At its final evolutionary step, treatments are limited to the percutaneous or surgical valve replacement, whatever the original cause of the degeneration. Understanding early molecular mechanisms that regulate valve interstitial cells remodeling and disease progression is challenging and could pave the way for future drugs aiming to prevent and/or reverse the process. Some valve degenerative processes such as the carcinoid heart disease, drug-induced valvulopathy and degenerative mitral valve disease in small-breed dogs are clearly linked to serotonin. The carcinoid heart is typically characterized by a right-sided valve dysfunction, observed in patients with carcinoid tumors developed from serotonin-producing gut enterochromaffin cells. Fenfluramine or ergot derivatives were linked to mitral and aortic valve dysfunction and share in common the pharmacological property of being 5-HT_2B receptor agonists. Finally, some small-breed dogs, such as the Cavalier King Charles Spaniel are highly prone to degenerative mitral valve disease with a prevalence of 40% at 4 years-old, 70% at 7 years-old and 100% in 10-year-old animals. This degeneration has been linked to high serum serotonin, 5-HT_2B receptor overexpression and SERT downregulation. Through the comprehension of serotonergic mechanisms involved into these specific situations, new therapeutic approaches could be extended to HVD in general. More recently, a serotonin dependent/ receptor independent mechanism has been suggested in congenital mitral valve prolapse through the filamin-A serotonylation. This review summarizes clinical and molecular mechanisms linking the serotonergic system and heart valve disease, opening the way for future pharmacological research in the field.

Carcinoid Heart Disease: A Review

Carcinoid heart disease remains a major cause of morbidity and mortality among patients with carcinoid syndrome and metastatic neuroendocrine tumors. Screening of all patients with N-terminal pro-B-type natriuretic peptide and transthoracic echocardiography is critical for early detection, as early symptoms and signs have low sensitivity for the disease. Cardiac surgery, in appropriate cases, is the only definitive therapy for advanced carcinoid heart disease, and it improves patient symptoms and survival. Management of carcinoid heart disease is complex, and multidisciplinary assessment of cardiac status, hormonal syndrome, and tumor burden is critical in guiding optimal timing of surgery.

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.

Primary Carcinoid Tumor of the Ovary: Report of an Unusual Case

Carcinoid tumors are endocrine malignancies that are often associated with a characteristic syndrome, the malignant carcinoid syndrome, which is most common in patients with small bowel tumors and liver metastases. In the rare instances when the syndrome is present without liver metastases the primary tumor is usually localized to the bronchus or ovary and secretes hormones directly into the systemic circulation. About two thirds of patients with carcinoid syndrome have evidence of carcinoid heart disease. We report on a case of a primary ovarian carcinoid tumor with an unusual clinical presentation.

Echocardiography in functional midgut neuroendocrine tumors: When and how often

The management of patients with midgut neuroendocrine tumors (MNET) is rapidly evolving. Current preoperative detection rates of primary tumor sites are higher than ever and progression-free survival in patients with already advanced disease is expanding due to the implementation of novel efficacious treatment strategies. This survival benefit may potentially translate into a need for a multidisciplinary approach to an even more heterogenous variety of clinical conditions, among these, carcinoid syndrome (CS) and carcinoid heart disease (CHD). The latter often triggers substantial morbidity and mortality, hence a systematic screening, an accurate diagnosis, as well as effective interventions are critically important. The rarity of the disease has result in a relative lack of statistically powerful evidence, which in turn may have rendered significant variability between practices. In this regard, despite recent guidelines, the optimal follow-up of patients with CHD remain debatable to some authors, perhaps due to the preponderance of certain schools throughout the manuscript. Herein, we present a concise and practical guidance document on clinical screening and echocardiographic surveillance of patients with CHD based on a comprehensive review of the literature, and complemented by our experience at the Center for Carcinoid and Neuroendocrine Tumors at The Mount Sinai Hospital.

Carcinoid Syndrome Complicating a Pancreatic Neuroendocrine Tumor: A Case Report

Neuroendocrine tumors (NETs) comprise a heterogeneous group of neoplasms. These tumors can produce a wide variety of hormones that can lead to syndromes of hormone excess, such as carcinoid syndrome. We present the case of a 47-year-old man who presented with right upper quadrant abdominal pain and emesis. He was found to have metastatic pancreatic NET and was treated with systemic chemotherapy. He subsequently developed dyspnea on exertion and was found to have severe right-sided heart disease secondary to elevated levels of serum serotonin. He was successfully treated with surgical tricuspid and pulmonic valve replacement. True carcinoid syndrome with pancreatic NETs is rare, but, as a treatable complication of the disease, is an important entity for which oncologists should be familiar.

The role of 5-HT2B receptors in mitral valvulopathy: bone marrow mobilization of endothelial progenitors

BACKGROUND AND PURPOSE

Valvular heart disease (VHD) is highly prevalent in industrialized countries. Chronic use of anorexigens, amphetamine or ergot derivatives targeting the 5-HT system is associated with VHD. Here, we investigated the contribution of 5-HT receptors in a model of valve degeneration induced by nordexfenfluramine, the main metabolite of the anorexigens, dexfenfluramine and benfluorex.

EXPERIMENTAL APPROACH

Nordexfenfluramine was infused chronically (28 days) in mice ((WT and transgenic Htr_2B   ^-/- , Htr_2A   ^-/- , and Htr_2B/2A   ^-/- ) to induce mitral valve lesions. Bone marrow transplantation was also carried out. Haemodynamics were measured with echocardiography; tissues and cells were analysed by histology, immunocytochemistry, flow cytometry and RT -qPCR. Samples of human prolapsed mitral valves were also analysed.

KEY RESULTS

Chronic treatment of mice with nordexfenfluramine activated 5-HT_2B receptors and increased valve thickness and cell density in a thick extracellular matrix, mimicking early steps of mitral valve remodelling. Lesions were prevented by 5-HT_2A or 5-HT_2B receptor antagonists and in transgenic Htr_2B   ^-/- or Htr_2A/2B   ^-/- mice. Surprisingly, valve lesions were mainly formed by numerous non-proliferative CD34⁺ endothelial progenitors. These progenitors originated from bone marrow (BM) as revealed by BM transplantation. The initial steps of mitral valve remodelling involved mobilization of BM-derived CD34⁺ CD31⁺ cells by 5-HT_2B receptor stimulation. Analysis of human prolapsed mitral valves showing spontaneous degenerative lesions, demonstrated the presence of non-proliferating CD34⁺ /CD309⁺ /NOS3⁺ endothelial progenitors expressing 5-HT_2B receptors.

CONCLUSIONS AND IMPLICATIONS

BM-derived endothelial progenitor cells make a crucial contribution to the remodelling of mitral valve tissue. Our data describe a new and important mechanism underlying human VHD.

mTOR Kinase Inhibition Effectively Decreases Progression of a Subset of Neuroendocrine Tumors that Progress on Rapalog Therapy and Delays Cardiac Impairment

Inhibition of mTOR signaling using the rapalog everolimus is an FDA-approved targeted therapy for patients with lung and gastroenteropancreatic neuroendocrine tumors (NET). However, patients eventually progress on treatment, highlighting the need for additional therapies. We focused on pancreatic NETs (pNET) and reasoned that treatment of these tumors upon progression on rapalog therapy, with an mTOR kinase inhibitor (mTORKi), such as CC-223, could overcome a number of resistance mechanisms in tumors and delay cardiac carcinoid disease. We performed preclinical studies using human pNET cells in vitro and injected them subcutaneously or orthotopically to determine tumor progression and cardiac function in mice treated with either rapamycin alone or switched to CC-223 upon progression. Detailed signaling and RNA sequencing analyses were performed on tumors that were sensitive or progressed on mTOR treatment. Approximately 57% of mice bearing pNET tumors that progressed on rapalog therapy showed a significant decrease in tumor volume upon a switch to CC-223. Moreover, mice treated with an mTORKi exhibited decreased cardiac dilation and thickening of heart valves than those treated with placebo or rapamycin alone. In conclusion, in the majority of pNETs that progress on rapalogs, it is possible to reduce disease progression using an mTORKi, such as CC-223. Moreover, CC-223 had an additional transient cardiac benefit on valvular fibrosis compared with placebo- or rapalog-treated mice. These results provide the preclinical rationale to further develop mTORKi clinically upon progression on rapalog therapy and to further test their long-term cardioprotective benefit in those NET patients prone to carcinoid syndrome. Mol Cancer Ther; 16(11); 2432-41. ©2017 AACR.

Diagnosing and Managing Carcinoid Heart Disease in Patients With Neuroendocrine Tumors: An Expert Statement

Carcinoid heart disease is a frequent occurrence in patients with carcinoid syndrome and is responsible for substantial morbidity and mortality. The pathophysiology of carcinoid heart disease is poorly understood; however, chronic exposure to excessive circulating serotonin is considered one of the most important contributing factors. Despite recognition, international consensus guidelines specifically addressing the diagnosis and management of carcinoid heart disease are lacking. Furthermore, there is considerable variation in multiple aspects of screening and management of the disease. The aim of these guidelines was to provide succinct, practical advice on the diagnosis and management of carcinoid heart disease as well as its surveillance. Recommendations and proposed algorithms for the investigation, screening, and management have been developed based on an evidence-based review of the published data and on the expert opinion of a multidisciplinary consensus panel consisting of neuroendocrine tumor experts, including oncologists, gastroenterologists, and endocrinologists, in conjunction with cardiologists and cardiothoracic surgeons.

Low Grade Neuroendocrine Tumors of the Lung

The lung is the second most common site of neuroendocrine tumors (NETs). Typical and atypical carcinoids are low-grade NETs of the lung. They present a favorable prognosis comported to the more common high-grade NETs. The low- and high-grade NETs require different treatment strategies; effective management of these tumors is essential to prolong survival and to manage the symptoms in patients with secretory or functional tumors. These rare tumors have received little attention and education is needed for treating physicians. This mini-review will concentrate mainly on advanced low-grade lung NETs. The article describes the classification of lung NETs and the diagnostic work-up. Different treatment methods including somatostatin analogs, peptide receptor radioligand therapy, and biologic systemic therapy are discussed. Promising results from recent trials are presented and discussed in the context of the lung primary site.