Functioning and nonfunctioning pNENs

Pancreatic neuroendocrine neoplasms (pNENs) are relatively rare tumors that have been increasingly recognized in recent years. They are highly heterogeneous and exhibit a diverse clinical course, along with a variable metastatic propensity related to their molecular biology profile, grade, primary tumor size, and functional status. The pNENs are divided into functioning and nonfunctioning tumor forms. Their pathological classification is based mainly on their histology and proliferative activity. Clinical challenges in their management include - but are not limited to - the inability to establish an early diagnosis in nonfunctioning pNENs and to accurately localize the source of hormonal secretion in functioning ones. Additionally, the role of active surveillance versus surgery for asymptomatic small nonfunctioning tumors is controversial, same as is the impact of palliative surgery in pNENs with distant metastases. Finally, in terms of an individualized treatment approach, there is a relative paucity of evidence on predictable, effective treatment strategies with respect to tumors and patient-related parameters.