Neuroendocrine Tumours: Diagnosis, Therapy and Follow-up

Neuroendocrine neoplasms (NENs) represent a clinically and pathologically heterogeneous group of tumours showing peculiar phenotypic characteristics and a common origin from cells of the diffuse neuroendocrine system [1–4]. NENs are commonly considered to be rare if compared to corresponding non-neuroendocrine neoplasms. Their frequency, however, has increased considerably in recent decades, as reported by epidemiological studies, such as the Surveillance, Epidemiology and End Results (SEER) registers in the USA, showing an increase of 1–5 new cases per 100,000/year [5]. In view of the more favourable prognosis of gastroenteropancreatic (GEP)-NEN than non-neuroendocrine neoplasms, the prevalence of GEP-NEN is 35 cases/100,000, shortly after colon adenocarcinoma and before all other gastroenteric adenocarcinomas [1].