Distribution of gastrointestinal neuroendocrine tumors in Europe: results from a retrospective cross-sectional study.

BACKGROUND: Gastrointestinal (non-pancreatic) neuroendocrine tumors (GI-NETs) represent a rare but increasingly common tumor entity. Prognosis and biological behavior of these tumors is extremely heterogenous and largely dependent on the specific tumor site, stage and differentiation. However, systematic data on the epidemiology of GI-NET, especially in terms of geographic distributions are missing. METHODS: We used the Oncology Dynamics database (IQVIA) to identify a total of 1354 patients with GI-NET from four European countries (Germany, France, Spain, UK) and compared them with regard to major patient and tumor related characteristics including patients' age, sex, tumor stage, tumor grading and differentiation. RESULTS: Out of the analyzed 1354 NET patients, 535 were found in the UK (39.5%), 289 in Germany (21.3%), 283 in Spain (20.9%) and 247 in France (18.2%). More patients were male than female (53.8% vs. 46.2%) with no significant differences between the analyzed countries. In contrast, the age distribution varied between the different countries, with the highest number of patients identified in the age groups of 61-70 years (31.0%) and 71-80 years (30.7%). The vast majority of patients showed a tumor origin in the small intestine, in German patients NET of the large intestine were slightly overrepresented and NET of the stomach underrepresented compared to all other countries. More than 80% of patients had stage IV disease at the time of diagnosis. Regarding tumor histology, most tumors showed a G2 tumor; interestingly, a G3 grading was found in 40.9% of patients in Germany (Ki-67 > 20%). CONCLUSION: The distribution of important patient- and tumor-specific characteristics of neuroendocrine tumors shows regional differences in four major European countries. These data may help to better understand the specific epidemiology of GI-NET in Europe.