Mental disorders of the depressive and anxiety spectrum in neuroendocrine tumors: prevalence, pathogenesis, clinical particulars

Abstract

Neuroendocrine tumors (NETs) are a heterogeneous group of slowly progressing tumors from neuroendocrine cells able to secrete biologically active substances. The most striking clinical manifestation of functioning NETs is the carcinoid syndrome, which is caused by serotonin overproduction and is most often associated with hot flashes, diarrhea, and abdominal pain. The prevalence of depressive and anxiety spectrum disorders in NETs patients can amount to 30–50%. The development of depressive and anxiety spectrum disorders in NETs can occur both through a nosogenic mechanism facilitated by a long pre-diagnostic stage, the presence of a serious disease with severe somatic symptoms and resulting significant decrease in quality of life. The mental disorders may be a result of somatogenic factors, which include an imbalance of significant mediators in the central nervous system (in particular, serotonin), as well as chronic inflammation and abnormalities of the body's immune defense. In the treatment of patients with NETs and verified anxiety and depressive disorders, special attention is paid to the safety of prescribing the first-line therapy, the selective serotonin reuptake inhibitors. The side effects of these agents are related to the activity of serotonin receptor agonists in the gut, which results in diarrhea and increased gastrointestinal motility, the symptoms similar to the carcinoid syndrome manifestations. The accumulated evidence allows concluding on the relative safety of serotoninergic antidepressants in NETs patients, but does not exclude some groups of patients with an increased risk of complications related to an additional effect on serotonin metabolism. Current knowledge on the prevalence, pathogenesis and treatment of depressive and anxiety spectrum disorders, comorbid to NETs, are limited and contradictory. Therefore, further studies with a larger patient samples are required to identify key factors of the pathophysiology and manifestation of mental disorders in NETs patients, which would generally facilitate the optimization of their treatment.