Prevalence of functional tumors in neuroendocrine carcinoma: An analysis from the NCCN NET database.

Abstract

4126 Background: Neuroendocrine tumors (NETs) are increasing in incidence and prevalence. Identification and treatment of specific clinical NET syndromes are established, yet there is uncertainty regarding the prevalence of NET with hormone-related symptoms versus nonfunctional tumors. Methods: The National Comprehensive Cancer Network (NCCN) created a comprehensive database to characterize patients (pts) treated for NETs. This database was queried to identify pts presenting to 7 NCCN institutions with a confirmed NET diagnosis: including carcinoid (cNET), pancreatic NET (pNET), NET not otherwise specified (NOS), and pheochromocytoma (PCC) between 2004 and 2010. The primary aim of this analysis was to describe demographic and clinical characteristics of NET pts by functional (fxn) status at diagnosis (dx). Results: Among 1244 NET pts, 26% (n=327) had an fxn tumor. Carcinoid syndrome (CS) occurred in 28% of cNET pts. The most common primary tumor sites among CS pts were small bowel (69%) and unknown (15%). Prevalence of hormonal syndrome (HS) among pNET pts was 22%, 24% among NOS pts and 37% among PCC pts. The majority of CS pts (74%), pNET HS pts (67%), and NOS HS pts (91%) had distant disease at dx, in contrast to 31% of PCC HS patients. Among CS pts with a known histologic grade, 91% were well differentiated (G1). Similarly, 86% of pNET HS and 67% of NOS HS pts with a known histologic grade had G1 NETs. The most common symptoms at dx among pts with CS included abdominal cramping (53%), change in bowel habits (48%), and flushing (40%). Among those tested, 85% of CS pts had a positive 5-HIAA test at dx. Among pNET HS pts, the most common symptoms present at dx were abdominal cramping (39%) and change in bowel habits (46%). The most common symptoms present at dx among NOS HS pts were abdominal cramping (35%), change in bowel habits (47%) and flushing (38%). Conclusions: Prevalence of CS in this NCCN database (28%) was slightly higher than the 10% previously reported in the literature. In contrast, the prevalence of HS among pNET pts (22%) was lower than previously reported. Approximately one quarter of cNET pts without metastatic disease had CS, warranting further analysis as CS most often occurs in the presence of liver metastasis.