Grade Increases in Gastroenteropancreatic Neuroendocrine Tumor Metastases Compared to the Primary Tumor

Neuroendocrinology. 2016;103(5):452-9. doi: 10.1159/000439434. Epub 2015 Aug 25.


Background/aim: The neuroendocrine tumor (NET) proliferation-based grading system (ENETS/WHO) for gastroenteropancreatic (GEP) tumors has proved reliable for prognostic stratification. To date, concerns exist regarding Ki-67 heterogeneity within the tumor and little is known on whether grade varies between primary and secondary sites. As tumor heterogeneity may have a significant impact on clinical management, our aim was to retrospectively evaluate Ki-67 on a series of GEP NETs in order to establish whether there is variability in different samples of the same lesion or between primary and metastatic disease (local/distant, synchronous/metachronous).

Methods: Sixty patients with multiple samples of tumor were accrued from a total of 338 GEP NETs; 44 of them also had tissue from local/distant metastases and a further 5 had multiple metastatic foci from unknown primary tumors. Immunohistochemistry for Ki-67 was performed on all paraffin blocks from both primary and metastatic tumors.

Results: Intratumor Ki-67 heterogeneity sufficient to change grade at first diagnosis was seen in 3/60 cases (5%). Out of 49 patients with primary NETs and/or multiple metastases, discrepancy in grade between sites was identified in 19 (39%) cases and in particular in 11/47 (23%) and in 10/12 (83%) patients with synchronous and metachronous metastases, respectively (p = 0.0002). Change in grade was more frequent in distant compared to locoregional metastases (p = 0.024) and in particular in distant sites other than the liver (p = 0.006).

Conclusions: NETs show frequent differences in grade between primary sites and their synchronous/metachronous metastases; assessment of Ki-67 at all sites may prove to be significant for patient management.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cell Proliferation
  • Female
  • Humans
  • Intestinal Neoplasms / metabolism
  • Intestinal Neoplasms / pathology*
  • Intestinal Neoplasms / secondary
  • Ki-67 Antigen / metabolism
  • Male
  • Middle Aged
  • Neoplasms, Second Primary / pathology*
  • Neuroendocrine Tumors / metabolism
  • Neuroendocrine Tumors / pathology*
  • Neuroendocrine Tumors / secondary
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology*
  • Pancreatic Neoplasms / secondary
  • Retrospective Studies
  • Stomach Neoplasms / metabolism
  • Stomach Neoplasms / pathology*
  • Stomach Neoplasms / secondary
  • Survival Analysis


  • Ki-67 Antigen

Supplementary concepts

  • Gastro-enteropancreatic neuroendocrine tumor