title: Do primary neuroendocrine tumors and metastasis have the same characteristics?
abstract: BACKGROUND
  Only one tumor site is usually biopsied to determine the histologic features of that patient's entire tumor burden. We hypothesized that there are significant histologic and functional differences in primary neuroendocrine tumors (NETS) and their nodal or organ metastases. We also hypothesized that limited tumor sampling could lead to erroneous assumptions about the tumor's histologic characteristics and clinical behavior.
  
  
  METHODS
  Thirteen patients with metastatic well differentiated midgut NETS underwent simultaneous removal of their primary tumor, nodal metastasis, and organ metastasis. Each tumor site was stained quantitatively for Ki-67, chromogranin A (CGA), synaptophysin, CD31, and Factor VIII. Samples were also evaluated with in vitro tumor angiogenesis and drug chemoresistance assays.
  
  
  RESULTS
  Ki-67 staining was nearly identical at all sites tested. Quantitative stains for CGA, synaptophysin, cluster of differentiation 31 (CD31), and Factor VIII varied considerably among the patient's three tissue site samples. Only 6% of the tissue samples tested against a battery of chemotherapeutic agents exhibited susceptibility to a single drug at all three tumor sites. In contrast, several antiangiogenic agents exhibited uniform effectiveness across all three tissue sites in multiple patients.
  
  
  CONCLUSIONS
  Sampling only one NET tumor site may lead to erroneous assumptions about the tumor's histologic features and functional behavior. Evaluation of primary tumors and their nodal and organ metastasis may be necessary to optimize clinical decision making.
authors.affiliation: Louisiana State University Health Sciences Center, Department of Surgery, Section of Surgical Endocrinology, New Orleans, Louisiana, USA.
authors.forename: Erika B
authors.initials: EB
authors.lastname: Lindholm
authors.forename: John
authors.initials: J
authors.lastname: Lyons
authors.forename: Catherine T
authors.initials: CT
authors.lastname: Anthony
authors.forename: J Philip
authors.initials: JP
authors.lastname: Boudreaux
authors.forename: Yi-Zarn
authors.initials: YZ
authors.lastname: Wang
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Woltering
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm; D006801:Humans; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic; D018358:Neuroendocrine Tumors / Q000378:metabolism / Q000473:pathology* / Q000556:secondary
chemical_list: D014408:Biomarkers, Tumor