title: Prognoses of GEP-NETS with undetermined malignant potentials of their primary sites.
abstract: OBJECTIVE
  In gastroenteropancreatic neuroendocrine tumors (GEP-NETs), primary lesions cannot be resected when the patients have highly advanced disease or when the primary sites are undefined. Such GEP-NETs cannot be evaluated with Ki-67 or the mitotic index. The aim of this study was to examine the prognosis of GEP-NETs that were ungraded by WHO G1-3 grading (U-NET group).
  
  
  METHODS
  Between 2000 and 2011, 75 patients with sporadic GEP-NETs were treated at our institution. The prognosis of patients graded as new WHO grading (G-NET group) was compared with that of the U-NET group. Cox proportional hazard regression analyses were performed to estimate the risk factors for overall survival (OS).
  
  
  RESULTS
  Overall 1-, 3- and 5-year survival rates were 90.7%, 79.9% and 74.9%, respectively. The odds ratio (OR) of patients with synchronous liver metastasis and U-NET was 1.73 (p=0.01) and 5.84 (p=0.002), respectively. Multivariate analyses of OS according to baseline characteristics revealed the only independent risk factor to be U-NET (OR, 3.95; p=0.02).
  
  
  CONCLUSIONS
  The malignant potential of U-NET may be no less than that of G-NET, while WHO-G3 patients have the worst prognoses in the G-NET group.
authors.affiliation: Department of Hepatobiliary Pancreatic Surgery, Tokyo Medical and Dental University, Tokyo, Japan. kudomsrg@tmd.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kudo
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ban
authors.forename: Takumi
authors.initials: T
authors.lastname: Akashi
authors.forename: Jiro
authors.initials: J
authors.lastname: Kumagai
authors.forename: Arihiro
authors.initials: A
authors.lastname: Aihara
authors.forename: Mikito
authors.initials: M
authors.lastname: Inokuchi
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kojima
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Kawano
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanaka
authors.forename: Shigeki
authors.initials: S
authors.lastname: Arii
mesh_terms: D000368:Aged; D001706:Biopsy; D016009:Chi-Square Distribution; D004067:Digestive System Neoplasms / Q000737:chemistry / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D007564:Japan; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000032:analysis; D008113:Liver Neoplasms / Q000556:secondary; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D008940:Mitotic Index; D015999:Multivariate Analysis; D060787:Neoplasm Grading; D018358:Neuroendocrine Tumors / Q000737:chemistry / Q000401:mortality / Q000556:secondary* / Q000628:therapy; D016017:Odds Ratio; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D019394:Ki-67 Antigen