Due to the lack of a diagnostic tumor marker (TM), the diagnosis of pancreatic neuroendocrine neoplasia (PNEN) is usually delayed, and a large part of patients present with regional (RM) and distant metastases (DM). The project aimed to assess the serum TM levels in PNEN and their relationships with disease extent and grade. One hundred fifteen patients with PNEN and 40 healthy subjects (HS) were enrolled. Most of the PNEN were well-differentiated (93.04%) and non-functional (93.91%). Beta-2 microglobulin (BMG), carbohydrate antigen 19-9 (CA19-9), carcinoembryonic antigen (CEA), cytokeratin 18 (CY18), and ferritin concentrations in PNEN patients were significantly higher than in HS (p < 0.01). The highest area under the curve (AUC) ≥ 0.7 for differentiating PNEN patients from HS had CY18, CA19-9, and ferritin (p < 0.001). PNEN disease was localized (LD) in 63 patients, 8 had RM, and 44 exhibited DM. Patients with metastatic PNEN (RM, DM) also showed significantly higher levels of CY18, CA125, and CEA than those without metastases (p < 0.05). In conclusion, CY18, CA19-9, and ferritin were serum biomarkers that fair diagnosed PNEN disease. Elevated CY18, CA125, and CEA levels correlated with clinical stages (RM, DM) and elevated CY18, CA125 with high grade (G3) of disease.