Clinical Features and Long Term Survival of Pancreatic Neuroendocrine Tumors According to the WHO Classification

ABSTRACT

PURPOSE: Clinical features of Pancreatic Neuroendocrine Tumors (PETs) vary according to the hormone secreted and to the heredity of the tumors. Malignant PETs are common among nonfunctioning PETs (NFTs) whereas the majority of functioning PETs (FTs) are benign. Our goal was to determine the clinical features and prognosis of PETs stratified by the WHO classification scheme and AJCC-UICC 7TH TNM staging. METHODS: We selected for study 30 patients with PETs, including one case of nesidiolastosis, who presented at our clinic between April 1992 and June 2010. Clinicopathological features were studied retrospectively. PETs were classified as benign, uncertain malignant, well differentiated carcinoma, or poorly differentiated carcinomas by the WHO classification. For statistical analysis, Student's t-test, the Chi-square test, and the Kaplan-Meier method were utilized. RESULTS: Nine cases were FTs and twenty one cases were NFTs. The average size of the FTs was smaller than that of the NFTs (1.71 vs 4.33, p=0.04). The head of the pancreas was most commonly involved (33.3% of FTs; 47.6% of NFTs) but the locations of the tumors were not different. Insulinoma was the most common (66.7%, 6/9) among FTs. The incidence of malignant tumors was 33.3% and 55.0% among, respectively, FTs and NFTs. The 5-year disease-free survival rate of patients with benign PETs (FTs and NFTs), and of patients with functioning well-differentiated carcinomas was 100%. However, the 5-year disease-free survival rates of patients with nonfunctioning well- and poorly-differentiated carcinomas were 66.7% and 0%. CONCLUSION: Among patients with Pancreatic Neuroendocrine Tumors, malignant tumors are more common among NFTs than FTs. Poorly-differentiated carcinomas have a worse prognosis while all FTs regardless of their WHO classification fail to show any disease recurrence.