title: Microscopic venous invasion in patients with pancreatic neuroendocrine tumor as a potential predictor of postoperative recurrence.
abstract: BACKGROUND
  Microscopic venous and lymphatic invasion is a known prognostic factor for various cancers, but its prognostic relevance for pancreatic neuroendocrine tumors (PNETs) is unclear.
  
  
  METHODS
  Thirty-two consecutive patients with PNET who had complete resection were included in this study. Venous and lymphatic invasion was identified on elastic tissue or immunohistochemical staining, and correlated with other clinicopathological factors, including recurrence-free survival.
  
  
  RESULTS
  Venous and lymphatic invasion was identified in nine (28%) and three (9%) patients, respectively. Tumors with venous invasion were of significantly larger size, higher Ki-67 index, and higher mitotic counts. Patients with venous invasion showed significantly worse prognosis than those without venous invasion (P = 0.001). Five of nine patients (56%) with venous invasion had tumor recurrence, while a relapse was found in one case in patients without venous invasion (n = 23). Lymphatic invasion was not correlated with any other clinicopathological parameters including lymph node metastasis and recurrence-free survival. Predictive factors for recurrence in univariate analysis included microscopic venous invasion, tumor size ≥ 20 mm, non-functionality, and WHO grades. In multivariate analysis where WHO grades and microscopic venous invasion were applied, venous invasion remained a significant predictor of poor recurrence-free survival (P = 0.021).
  
  
  CONCLUSIONS
  Microscopic venous invasion may serve as a predictive factor for tumor recurrence in patients with resectable PNET. The combination of WHO grades and microscopic venous invasion may assist in the stratification of the patients for risk of tumor recurrence.
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Nanno
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan. Electronic address: toyama@med.kobe-uc.ac.jp.
authors.forename: Hirochika
authors.initials: H
authors.lastname: Toyama
authors.affiliation: Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Otani
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Sadaki
authors.initials: S
authors.lastname: Asari
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Goto
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Sachio
authors.initials: S
authors.lastname: Terai
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ajiki
authors.affiliation: Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Yoh
authors.initials: Y
authors.lastname: Zen
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Fukumoto
authors.affiliation: Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Yonson
authors.initials: Y
authors.lastname: Ku
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001808:Blood Vessels / Q000000981:diagnostic imaging / Q000473:pathology*; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D009364:Neoplasm Recurrence, Local; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies
keywords: Microscopic venous invasion; Pancreatic neuroendocrine tumor; Prognosis; Recurrence