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

BACKGROUND: 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.

STUDY DESIGN: 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.

RESULTS: 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.

CONCLUSIONS: Primary pancreatic carcinoid tumors are increasingly being diagnosed. Differentiating PNET subtypes plays an important role in prognostication. Resection remains a critical component of care.