Analysis of 100 consecutive cases of resectable pancreatic neuroendocrine neoplasms: clinicopathological characteristics and long-term outcomes

The incidence rate of pancreatic neuroendocrine neoplasms (pNENs) has increased rapidly in recent years. However, the clinicopathological characteristics of pNENs are poorly understood. Medical records of patients who underwent surgery and were confirmed as pNENs by pathological examination from January 2003 to February 2015 in Qilu Hospital were reviewed retrospectively. A total of 100 patients, 36 males and 64 females, were included with a mean operation age of 46.26 +/- 13.41 years. Among the 100 cases, 76 had insulinomas and 24 had non-functional pNENs. Tumor size ranged from 0.5 cm to 9 cm, and the mean size was 2.20 +/- 1.40 cm. The percentages of TNM stages I, II, III, and IV tumors were 89.0%, 8.0%, 0.0%, and 3.0%, respectively. Based on the WHO classification, pNENs were classified into three grades: G1, G2, and G3. G1, G2, and G3 tumors were confirmed in 72.9%, 23.7%, and 3.4% patients, respectively. The positive rates of CgA and Syn immunohistochemical staining were 94.5% (69/73) and 100% (74/74), respectively. Compared with insulinoma, non-functional pNENs have larger tumor sizes, more advanced TNM staging, a higher Ki-67 index, and a higher rate of liver metastasis (P < 0.05). In conclusion, pNENs are heterogeneous tumors with varying clinical manifestations, diverse tumor biological characteristics, and different prognoses. Non-functional pNENs present a more aggressive behavioral model and have poorer prognosis than functional pNENs.