Portuguese Pancreatic Club Perspectives on the Epidemiology and Clinical Presentation of Pancreatic Neuroendocrine Tumours

Background: Pancreatic neuroendocrine neoplasms are a specific subgroup of pancreatic tumours due to their distinct biological and histological behaviour, with a consequently unique clinical approach. Although rare, they constitute 1–5% of all pancreatic tumours, being second in frequency after ductal adenocarcinoma. With growing incidence since the first data were published in 1970, more recent studies estimate 1,000 new cases yearly in the USA. Summary: Although 80–90% of well-differentiated pancreatic neuroendocrine tumours (panNETs) are sporadic, their association with hereditary syndromes such as multiple endocrine neoplasia type 1, von Hippel-Lindau syndrome, neurofibromatosis type 1, and tuberous sclerosis, is well documented. According to the World Health Organization, they can be classified as functioning or non-functioning (NF) regarding their association with clinical syndromes due to hormone secretion. NF tumours, which are about 90% of panNETs, are generally asymptomatic but may present with abdominal pain and biliary or gastric obstruction, secondary to tumour mass compression. Clinical manifestations of functioning neoplasms are associated with the hormone they secrete. In older studies, survival rates of well-differentiated panNETs were around 33% at 5 years, 17% at 10 years, and 10% at 20 years. Most recent data indicate a 5-year overall survival rate of 28% for metastatic tumours. Among the functioning tumours, insulinoma is typically the least aggressive, unlike gastrin, glucagon, or somatostatin-producing tumours, which generally have a worse prognosis. Key Messages: In this review, we will highlight the recent epidemiological data of panNETs and summarize the clinical presentation of sporadic tumours, including the most frequent functioning panNETs.