title: Vascularity and Tumor Size are Significant Predictors for Recurrence after Resection of a Pancreatic Neuroendocrine Tumor.
abstract: BACKGROUND
  It is difficult to identify patients at high risk of recurrence after pancreatectomy for pancreatic neuroendocrine tumor (PNET) using only the grading classification, especially the G2 category, which includes both benign and low- and high-grade malignant tumors.
  
  
  METHODS
  Forty-one patients with PNET who underwent pancreatectomy were enrolled in this study. We defined the computed tomography (CT) ratio as the CT value of the tumor divided by that of non-tumorous pancreatic parenchyma using the late arterial phase dynamic CT. The optimal cut-off values for CT ratio and tumor size were determined using p-values that were calculated using the log-rank test.
  
  
  RESULTS
  The optimal cut-off values of CT ratio and tumor size for dividing patients into groups according to the greatest difference in disease-free survival (DFS) were 0.85 (p < 0.001) and 3.0 cm (p < 0.001), respectively. In analysis using Spearman's correlation coefficient, CT ratio (p = 0.007) and tumor size (p = 0.003) were individually associated with the Ki-67 proliferative index. Cox proportional hazard analysis identified that a CT ratio <0.85 (n = 10, p = 0.006) and tumor size ≥3.0 cm (n = 13, p = 0.023) were independent prognostic factors associated with DFS. All patients in the CT ratio ≥0.85 and tumor size <3.0 cm group (n = 23, including seven patients with G2 disease) did not develop recurrence after surgery. On the other hand, 5-year DFS in the CT ratio <0.85 and tumor size ≥3.0 cm group (n = 5, including three patients with G2 disease) was zero.
  
  
  CONCLUSIONS
  PNETs with a CT ratio <0.85 and tumor size ≥3.0 cm should be considered as having a high risk of recurrence after pancreatectomy.
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan. yusu.yamamoto@scchr.jp.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Yukiyasu
authors.initials: Y
authors.lastname: Okamura
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Sunao
authors.initials: S
authors.lastname: Uemura
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Teiichi
authors.initials: T
authors.lastname: Sugiura
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Ito
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Ashida
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Kato
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Ohgi
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Mihoko
authors.initials: M
authors.lastname: Yamada
authors.affiliation: Division of Pathology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Sasaki
authors.affiliation: Division of Radiology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Aramaki
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Shizuoka Cancer Center, 1007, Shimo-Nagakubo, Sunto-Nagaizumi, Shizuoka, 4118777, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Uesaka
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000556:secondary* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging / Q000473:pathology*; D018358:Neuroendocrine Tumors / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D010180:Pancreatectomy; D010190:Pancreatic Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000379:methods