VIP and gastrin-producing neuroendocrine tumor: The relatively rare thymic NEN shows the highest risk (hazard ratio [HR] of 4.64), followed by functional glucagon, somatostatin, and vasoactive intestinal peptide (VIP) secreting PNEN (HR 4.29), non-functional PNEN (HR 3.43) and gastrinomas (HR 1.89) [10].