title: Neuroendocrine tumors of the pancreas: Degree of cystic component predicts prognosis.
abstract: Although most pancreatic neuroendocrine tumors are solid, approximately 10% are cystic. Some studies have suggested that cystic pancreatic neuroendocrine tumors are associated with a more favorable prognosis.
  
  
  
  A retrospective review of all patients with pancreatic neuroendocrine tumors who underwent operative resection between 1999 and 2014 at a single academic medical center was performed. Based on cross-sectional imaging performed before operation, pancreatic neuroendocrine tumors were classified according to the size of the cystic component relative to the total tumor size: purely cystic (100%), mostly cystic (≥50%), mostly solid (<50%), and purely solid (0%). Clinicopathologic characteristics and recurrence-free survival were assessed between groups.
  
  
  
  In the study, 214 patients met inclusion criteria: 8 with purely cystic tumors, 7 with mostly cystic tumors, 15 with mostly solid tumors, and 184 with purely solid tumors. The groups differed in terms of tumor size (1.5 ± 0.5, 3.0 ± 1.7, 3.7 ± 2.6, and 4.0 ± 3.5 cm), lymph node positivity (0%, 0%, 26.7%, and 34.2%), intermediate or high grade (0%, 16.7%, 20.0%, and 31.0%), synchronous liver metastases (0%, 14.3%, 20.0%, and 26.6%) and need for pancreaticoduodenectomy (0%, 0%, 6.7%, and 25.0%), respectively. No cases of purely cystic pancreatic neuroendocrine tumors were associated with synchronous liver or lymph node metastasis, intermediate/high grade, recurrence, or death due to disease. Among patients presenting without metastatic disease, 10-year recurrence-free survival was 100% in patients with purely and mostly cystic tumors versus 53.0% in patients with purely and mostly solid tumors; however, this difference did not reach statistical significance.
  
  
  
  Pancreatic neuroendocrine tumors demonstrate a spectrum of biologic behavior with an increasing cystic component being associated with more favorable clinicopathologic features and prognosis. Purely cystic pancreatic neuroendocrine tumors may represent 1 subset that can be safely observed without immediate resection.
authors.affiliation: Department of Surgery, Stanford University, CA.
authors.forename: Jordan M
authors.initials: JM
authors.lastname: Cloyd
authors.affiliation: Department of Surgery, Stanford University, CA.
authors.forename: Kimberly E
authors.initials: KE
authors.lastname: Kopecky
authors.affiliation: Department of Surgery, Stanford University, CA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Norton
authors.affiliation: Division of Oncology, Stanford University, CA.
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Kunz
authors.affiliation: Division of Oncology, Stanford University, CA.
authors.forename: George A
authors.initials: GA
authors.lastname: Fisher
authors.affiliation: Department of Surgery, Stanford University, CA.
authors.forename: Brendan C
authors.initials: BC
authors.lastname: Visser
authors.affiliation: Department of Surgery, Stanford University, CA.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Dua
authors.affiliation: Department of Medicine and Gastroenterology, Stanford University, CA.
authors.forename: Walter G
authors.initials: WG
authors.lastname: Park
authors.affiliation: Department of Surgery, Stanford University, CA. Electronic address: gpoultsides@stanford.edu.
authors.forename: George A
authors.initials: GA
authors.lastname: Poultsides
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D018358:Neuroendocrine Tumors / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D010180:Pancreatectomy; D010190:Pancreatic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome