Nutritional Complications and the Management of Patients with Gastroenteropancreatic Neuroendocrine Tumors.

Neuroendocrine tumors (NETs) have increased in incidence and prevalence over the past 2 decades and affect approximately 170,000 people in the United States alone. Gastroenteropancreatic (GEP) NETs (GEP NET) are a heterogeneous group of rare tumors that have distinct effects on the body due to their tumor location and potential to secrete hormones and peptides. Clinical practice guidelines and consensus guidelines for GEP NETs with regard to best practice for diagnosis, treatment, and medical management are available, but the supportive care needs and optimal nutritional management of patients affected by these unique tumors remain under-researched: evidence to guide clinical practice is lacking. The pathophysiology of the disease and its treatment can cause various symptoms that can have significant effects on vitamin synthesis and absorption, dietary habits, weight change, and appetite. Deficiency of fat-soluble vitamins and niacin exists amongst patients with GEP NET, particularly those on treatment with somatostatin analogs and with serotonin-secreting tumors, respectively. Malnutrition and dietary modification amongst patients with GEP NET is more prevalent than initially thought: up to 25% of inpatients with GEP NET are malnourished. Food intolerance is also reported in up to 40-90% of these patients, though its misdiagnosis is common. This review summarizes the evidence regarding the impact of GEP NET and its treatment on nutritional factors in these patients with emphasis on malnutrition, vitamin deficiencies, dietary intake, and quality of life. Recommendations for clinical practice and research approaches to address these nutritional issues are discussed.