Somatostatin Receptor SSTR-2a Expression Is a Stronger Predictor for Survival Than Ki-67 in Pancreatic Neuroendocrine Tumors

Medicine (Baltimore). 2015 Oct;94(40):e1281. doi: 10.1097/MD.0000000000001281.


Somatostatin receptors (SSTR) are commonly expressed by neuroendocrine tumors. Expression of SSTR-2a and SSTR-5 may impact symptomatic management; however, the impact on survival is unclear. The aim of this study is to correlate SSTR-2a and SSTR-5 expression in pancreatic neuroendocrine tumors (PNETs) with survival. This study is designed to determine the prognostic significance of somatostatin receptors SSTR-2a and SSTR-5 in PNETs. This retrospective cohort study included cases of resected PNETs between 1992 and 2014. Clinical data, histopathology, expression of SSTR and Ki-67 by immunohistochemistry, and long-term survival were analyzed. A total of 99 cases were included in this study. The mean age was 57.8 years (18-87 years) and median tumor size was 25 mm (range 8-160 mm). SSTR-2a and SSTR-5 expression was scored as negative (n = 19, 19.2%; n = 75, 75.8%, respectively) and positive (n = 80, 80.1%; n = 24, 24.2%). The median follow-up was 49 months. SSTR-2a expression was associated with improved overall survival, with cumulative survival rates at 1, 3, and 5 years being 97.5%, 91.5%, and 82.9%, respectively. Univariate analysis demonstrated better survival in SSTR-2a positive patients (log rank P = 0.04). SSTR-5 expression was not associated with survival outcomes (log rank P = 0.94). Multivariate analysis showed that positive SSTR-2a expression is a stronger prognostic indicator for overall survival [Hazard Ratio (HR): 0.2, 95% Confidence interval (CI): 0.1-0.8] compared to high Ki-67 (HR: 0.8, 95% CI: 0.1-5.7). Expression of SSTR-2a is an independent positive prognostic factor for survival in PNETs.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Humans
  • Immunochemistry
  • Ki-67 Antigen / analysis
  • Middle Aged
  • Neuroendocrine Tumors / chemistry
  • Neuroendocrine Tumors / mortality*
  • Pancreatic Neoplasms / chemistry
  • Pancreatic Neoplasms / mortality*
  • Prognosis
  • Receptors, Somatostatin / analysis*
  • Retrospective Studies


  • Ki-67 Antigen
  • Receptors, Somatostatin
  • somatostatin receptor 5
  • somatostatin receptor 2