National Rise of Primary Pancreatic Carcinoid Tumors: Comparison to Functional and Nonfunctional Pancreatic Neuroendocrine Tumors

Abstract

New guidelines recommend differentiating between carcinoid and pancreatic neuroendocrine tumors (PNETs) during clinical trials. However, little is known about the behavior and incidence of primary pancreatic carcinoid tumors. We performed a retrospective cohort study using the National Cancer Data Base (NCDB) to identify adults with primary PNETs diagnosed between 2004 and 2013. The Kaplan-Meier method was used to evaluate overall survival, and multivariate Cox proportional hazards model was used to assess the hazard of death in resected patients. Of 10,752 patients, 12.7% were diagnosed with carcinoid tumors, 84.7% with nonfunctional and 2.6% with functional PNETs. Although the number of functional PNETs has remained relatively constant over time, rates of nonfunctional and carcinoid tumors have risen dramatically. Only 36 (5.7%) carcinoid tumors were diagnosed in 2004; this increased to 497(27.7%) in 2013. Overall survival was significantly longer for carcinoid compared with functional and nonfunctional tumors (log-rank p < 0.0001), with 5-year survival rates of 63.1%, 58.3%, and 52.6%, respectively. For patients having resection, overall survival further improved for carcinoid tumors relative to functional (log-rank p= 0.0011) and nonfunctional (log-rank p < 0.0001) tumors, but the survival difference between functional and nonfunctional tumors disappeared (log-rank p= 0.4579); 5-year survival rates were 89.2%, 76.6%, and 78.7%, respectively. On multivariate Cox regression of the resected cohort, mortality was significantly higher for patients with functional (hazard ratio [HR] 1.81) and nonfunctional (HR 1.40) PNETs compared with carcinoid tumors. Primary pancreatic carcinoid tumors are increasingly being diagnosed. Differentiating PNET subtypes plays an important role in prognostication. Resection remains a critical component of care.