Evaluation of the current treatment strategies for pancreatic neuroendocrine tumors.

Abstract

611 Background: The management of pancreatic neuroendocrine tumors (PNET) varies between observation (O), pancreatic resection (PR) and enucleation (E). Currently, size, grade and location are used to determine which treatment strategy may be employed. We sought to evaluate each strategy and further clarify the role for surgery. Methods: Utilizing the National Cancer Database we identified patients with pancreatic neuroendocrine tumors. Tumors were stratified based upon size <1cm, 1-2cm and >2 cm. Mann-Whitney U and Kruskal were used to compare continuous variables and Pearson’s Chi-square test was used to compare categorical variables. Unadjusted survival analyses were performed using the Kaplan-Meier method. Multivariate analysis (MVA) was performed to identify predictors of survival. All statistical tests were two-sided and p<0.05 was considered significant. Results: We identified 17,921 patients. (<1cm, 1214, 1-2cm, 4325, and >2cm, 12,382) with a median age of 61.5 (18-90). Males more often presented with tumors >2cm, 56% vs 44%, <0.001. Tumors >2cm were more likely to be poorly differentiated (PD), p<0.001, have node positive disease, p<0.001 and less likely to undergo R0 resection, p<0.001. Tumors <1cm and well differentiated (WD) the median and overall 5-year survival in the O group was not reached (NR) (77%) vs 142.6 months (87%) in the surgery groups, p<0.04; in the 1-2 cm WD group 95.7 months and 60% vs NR and 94%, p<0.001. Similarly in the PD tumors <1cm the median and overall survival was 32.9 months and 24% in the O vs NR and 81%, p<001; in the 1-2 cm group 14.8 months and 19% vs NR and 73%, p<0.001. There were no differences in survival in patients undergoing PR or E, p=0.09. MVA revealed age, grade, Charleson Deyo score, tumor size, tumor location, and surgery (PR or E) were all independent predictors of survival. Conclusions: While observation is currently an acceptable option for the management of small <1cm WD PNET, we found an improvement in survival in the patients undergoing surgery. Additionally, 1-2 cm PNET benefited from the surgical approach. Enucleation and pancreatic resection did not differ in overall survival. Surgery for PNET should be considered as the first line treatment of these patients.