Somatostatin Analogs and Tumor Localization Do Not Influence Vitamin D Concentration in Patients with Neuroendocrine Tumors

Patients with neuroendocrine tumors (NETs), malignancies of rare but still rising incidence, may be a group at higher risk of vitamin D insufficiency. The gastrointestinal tumor prevalence and somatostatin analog (SSA) therapy may cause vitamin D malabsorption. The aim of this study was to evaluate the serum level of vitamin D in NET patients. A total of 36 NET patients were enrolled into the experimental group and 16 individuals were enrolled into the control group. All patients were further classified into subgroups according to primary tumor localization (gastropancreatic, lung, and other NETs) or therapy (with or without SSA treatment). The concentrations of total 25(OH)D were assayed with Electrochemiluminescence immunoassay (ECLIA). Serum concentration of 25(OH)D in NET patients did not differ significantly from that of the control group. However, the average level of 25(OH)D in both groups met the criteria of vitamin D deficiency. Importantly, SSA therapy did not aggravate vitamin D deficiency. Moreover, the concentration of 25(OH)D in the studied group was not significantly influenced by primary tumor localization, patient age, or season. Vitamin D deficiency is a widespread disorder affecting both NET patients and individuals without other health problems, and SSA and gastrointestinal tumor localization do not exacerbate this condition.