title: Surveillance strategy for small asymptomatic non-functional pancreatic neuroendocrine tumors - a systematic review and meta-analysis.
abstract: Non-functional pancreatic neuroendocrine tumors (NF-PNET) are rare neoplasms being increasingly diagnosed. Surgical treatment or expectant management are both suggested for small NF-PNETs. The aim of this study was to evaluate the outcome of surveillance strategy for small NF-PNETs.
  
  
  
  A systematic search was performed up to March 2016 in MEDLINE, EMBASE and the Cochrane Library according to the PRISMA guidelines. Data was pooled using the random-effects model.
  
  
  
  Nine articles including 344 patients with sporadic and 64 patients with MEN1 related NF-PNET were selected. Tumor growth was observed in 22% and 52%, development of metastases were reported on 0% and 9%, and rate of secondary surgical resection was 12% and 25% in patients with sporadic or MEN1 related NF-PNETs, respectively. All metastases (1 distant, 4 nodal) were reported by a single study in patients with MEN1. Reason for secondary surgery was tumor growth in half of patients undergoing surgery.
  
  
  
  Expectant management of small asymptomatic, sporadic, NF-PNETs could be a reasonable option in highly selected patients. However, the level of evidence is low and longer follow-up is needed to identify patients could benefit from upfront surgery instead of expectant treatment.
authors.affiliation: Department of Abdominal Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland; Department of Transplantation and Liver Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland. Electronic address: ville.sallinen@helsinki.fi.
authors.forename: Ville
authors.initials: V
authors.lastname: Sallinen
authors.affiliation: Department of Surgery, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Tessa Y S
authors.initials: TY
authors.lastname: Le Large
authors.affiliation: General Surgery Department, Saint Luke's Clinical Hospital, Saint-Petersburg, Russia.
authors.forename: Shamil
authors.initials: S
authors.lastname: Galeev
authors.affiliation: Federal Medical and Rehabilitation Center, Department of Surgical Oncology, Moscow, Russia.
authors.forename: Zahar
authors.initials: Z
authors.lastname: Kovalenko
authors.affiliation: Department of Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Tieftrunk
authors.affiliation: Department of Upper Gastrointestinal and Hepato-Pancreato-Biliary Surgery, Barretos Cancer Hospital, Barretos, São Paulo, Brazil.
authors.forename: Raphael
authors.initials: R
authors.lastname: Araujo
authors.affiliation: Department of Surgery, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
authors.forename: Güralp O
authors.initials: GO
authors.lastname: Ceyhan
authors.affiliation: Department of Digestive and Endocrine Surgery, Cochin Hospital, APHP, Paris, France; Faculté de Médecine Paris Descartes, Université Paris Descartes, Sorbonne Paris Cité, France. Electronic address: sebastien.gaujoux@aphp.fr.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Gaujoux
mesh_terms: D000328:Adult; D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000556:secondary / Q000601:surgery / Q000628:therapy*; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D018579:Patient Selection; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D047368:Tumor Burden; D057832:Watchful Waiting