Population-Level Analysis of Pancreatic Neuroendocrine Tumors 2 cm or Less in Size

There is a paucity of evidence regarding incidence and predictors of survival in pancreatic neuroendocrine tumors (PNETs) a parts per thousand currency sign2 cm in size. Patients having undergone resection for nonfunctioning PNETs were selected from the SEER database (1988-2009) and an institutional pathology database (1996-2012). PNETs a parts per thousand currency sign2 cm were compared with PNETs > 2 cm. Data were analyzed with chi (2) tests, ANOVA, the Kaplan-Meier method, log rank tests, and Cox proportional hazard, and binary logistic regression. The incidence of PNETs a parts per thousand currency sign2 cm in the United States has increased by 710.4 % over the last 22 years. Rates of extrapancreatic extension, nodal metastasis, and distant metastasis in PNETs a parts per thousand currency sign2 cm in the SEER database were 17.9, 27.3, and 9.1 %, respectively. The rate of nodal metastasis in our institutional series was 5.7 %. Disease-specific survival at 5, 10, and 15 years for PNETs a parts per thousand currency sign2 cm was 91.5, 84.0, and 76.8 %. Decreased disease-specific survival was not associated with nodal metastasis, but rather with high grade [moderately differentiated, hazard ratio (HR) 37.2, 95 % confidence interval (CI) 2.7-518.8; poorly differentiated, HR 94.2, 95 % CI 4.9-1,794.4; reference, well differentiated], and minority race (Asian, HR 30.2, 95 % CI 3.1-291.7; Black, HR 60.1, 95 % CI 2.1-1,027.9; reference, White). Pancreatic neuroendocrine tumors a parts per thousand currency sign2 cm are increasingly common, and the most significant predictors of disease-specific survival are grade and race. The SEER database excludes PNETs considered to be benign, and rates of extrapancreatic extension, nodal metastasis, and distant metastasis are overestimated. Small size, however, does not preclude malignant behavior.