Abstract
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.
Highlights
Neuroendocrine neoplasms (NENs) are derived from enterochromaffin cells of the diffuse neuroendocrine system, which are mainly present in the gastrointestinal tract [1]
Imatinib targets the platelet-derived growth factor (PDGF) receptor and showed decreased organ fibrosis in scleroderma and pulmonary fibrosis but has not been evaluated as antifibrotic therapy [58]. Angiogenesis inhibitors such as vascular endothelial growth factor (VEGF), tyrosine kinase inhibitors, and inhibitors of the fibroblast growth factor pathways are currently been studied in patients with neuroendocrine neoplasm, but none of these studies focus on antifibrotic effects of these drugs [50]
Carcinoid syndrome can develop in patients with hormone producing neuroendocrine neoplasms
Summary
Neuroendocrine neoplasms (NENs) are derived from enterochromaffin cells of the diffuse neuroendocrine system, which are mainly present in the gastrointestinal tract [1]. E prevalence of carcinoid syndrome within all NEN was reported as between 18% [10] and 72% [11] based on older series. A recent article by Halperin et al analyzed the SEER database in the USA, and this demonstrated that 19% of patients with neuroendocrine neoplasm had carcinoid syndrome, giving an overall incidence of carcinoid syndrome of 1 : 100 000 population [14]. Patients with carcinoid syndrome have an overall survival of 4.7 years compared with 7.1 year in patients without symptoms of carcinoid syndrome [14]. Within this minireview, we will discuss symptoms, an update in pathophysiology, and new treatment possibilities and focus on some common complications as carcinoid heart disease, mesenteric fibrosis, and carcinoid crisis and on more uncommon psychiatric disorders and its treatment in patients with CS
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