Differential Diagnosis of Diarrhea in Patients With Neuroendocrine Tumors

Update in the management of gastroenteropancreatic neuroendocrine tumors

Neuroendocrine neoplasms are a diverse group of neoplasms that can occur in various areas throughout the body. Well-differentiated neuroendocrine tumors (NETs) most often arise in the gastrointestinal tract, termed gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Although GEP-NETs are still uncommon, their incidence and prevalence have been steadily increasing over the past decades. The primary treatment for GEP-NETs is surgery, which offers the best chance for a cure. However, because GEP-NETs are often slow-growing and do not cause symptoms until they have spread widely, curative surgery is not always an option. Significant advances have been made in systemic and locoregional treatment options in recent years, including peptide-receptor radionuclide therapy with α and β emitters, somatostatin analogs, chemotherapy, and targeted molecular therapies.

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.

Bile Acid Malabsorption in Patients with Neuroendocrine Tumors

BACKGROUND

Chronic diarrhea in patients with neuroendocrine tumors (NET) may be caused by bioactive products of NET, bile acid malabsorption (BAM), ileal resection (IR) or steatorrhea.

AIM

To quantitate BA and fat malabsorption in NET with diarrhea.

METHODS

Part of evaluation in medical oncology clinical practice, 67 patients [42F, 25 M; median age 64.0 y (17.0 IQR)] with well-differentiated NET and diarrhea underwent clinically indicated measurements of 48-h fecal BA [(FBA), fecal weight (normal < 400 g/48 h), fecal fat (normal < 7 g/day) in n = 52] and fasting serum 7αC4 (marker of hepatic BA synthesis, n = 30) between 01/2018 and 11/2020. IR had been performed in 45 patients. BAM diagnosis was based on FBA criteria: elevated total FBA (> 2337 µmol/48 h) or > 10% primary FBA or combination > 4% primary FBA plus > 1000 µmol total FBA/48 h. We also measured fecal elastase (for pancreatic insufficiency) in 13 patients.

RESULTS

BAM was present in 48/52 (92%) patients with NET. There were significant correlations between total FBA and 48-h fecal weight (R_s = 0.645, P < 0.001). Mean length of IR was 47 cm; in patients with IR < 25 cm, total FBA was elevated in 85% and primary FBA > 10% in 69%. In 22 patients with no IR, 13/15 tested (87%) had BAM. Among 6 patients with pancreatic NET and no IR, 80% had BAM. Fecal fat was ≥ 15 g/day in 18/42 (43%). In 4/17 (24%) with IR < 25 cm and 8/19 (42%) patients with IR > 25 cm fecal fat was 44.0 (40.5) and 38.0 (38.0)g/day, respectively.

CONCLUSION

A majority of patients with NET and diarrhea had BAM, even with < 25 cm or no IR.

What Gastroenterologists Should Know about Carcinoid Syndrome

Carcinoid syndrome (CS) is the most common functional syndrome associated with neuroendocrine neoplasia (NEN), particularly in intestinal NEN with extensive liver metastases. Owing to the heterogenous symptomatic scenario present in CS, recognition of these patients may be challenging. In this review, we explore some key clinical factors used to identify patients affected by CS, with particular focus on differential diagnoses of diarrhea, which is the main symptom of CS. Moreover, we highlight the importance of nutritional screening as a clinical indication to prevent malnutrition and to manage the most common nutrient deficiencies present in these patients.

Neuroendocrine neoplasia and bone (Review)

This is a narrative review focusing on neuroendocrine neoplasia (NEN) and bone status, in terms of metastases and osteoporosis/fractures. One fifth of NEN have skeletal dissemination, this affinity being regulated by intrinsic tumor factors such as the C-X-C chemokine receptor 4 (CXCR4). Bone colonization impairs the patient quality of life, representing a surrogate of reduced survival. Patients with NEN without bone metastases may exhibit low bone mineral density, perhaps carcinoid-related osteoporosis, yet not a standardized cause of osteoporosis. Case-finding strategies to address bone health in NEN with a good prognosis are lacking. Contributors to fractures in NEN subjects may include: menopausal status and advanced age, different drugs, induced hypogonadism, malnutrition, malabsorption (due to intestinal resection, carcinoid syndrome), hypovitaminosis D, impaired glucose profile (due to excessive hormones such as glucagon, somatostatinoma or use of somatostatin analogues), various corticoid regimes, and high risk of fall due to sarcopenia. Pheocromocytoma/paraganglioma involve bone through malignant forms (bone is an elective site) and potential secondary osteoporosis due to excessive hormonal content and increased sympathetic activity which is a key player of bone microarchitecture/quality as reflected by low Trabecular Bone Score. Glucocorticoid osteoporosis is related to NEN-associated ectopic Cushing syndrome. Currently, there are a lack of studies to emphasis that excessive gut-derivate serotonin in NENs with carcinoid syndrome is a specific activator of bone loss thus a contributor to carcinoid-related osteoporosis.