title: Somatostatin Receptor SSTR-2a Expression Is a Stronger Predictor for Survival Than Ki-67 in Pancreatic Neuroendocrine Tumors.
abstract: 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.
authors.affiliation: From Department of Gastrointestinal Surgery, Royal North Shore Hospital and North Shore Private Hospital, University of Sydney, New South Wales, Australia (SM, PDR, PG, AM, JSS); Department of Medical Oncology, Royal North Shore Hospital and North Shore Private Hospital, University of Sydney, New South Wales, Australia (NP, SC); Macquarie University Hospital, Macquarie University, New South Wales, Australia (JSS); and Department of Anatomical Pathology Royal North Shore Hospital, Cancer Diagnosis and Pathology Group, Kolling Institute of Medical Research, University of Sydney, New South Wales, Australia (JA, LDU, AJG).
authors.forename: Shreya
authors.initials: S
authors.lastname: Mehta
authors.forename: Philip R
authors.initials: PR
authors.lastname: de Reuver
authors.forename: Preetjote
authors.initials: P
authors.lastname: Gill
authors.forename: Juliana
authors.initials: J
authors.lastname: Andrici
authors.forename: Lisa
authors.initials: L
authors.lastname: D'Urso
authors.forename: Anubhav
authors.initials: A
authors.lastname: Mittal
authors.forename: Nick
authors.initials: N
authors.lastname: Pavlakis
authors.forename: Stephen
authors.initials: S
authors.lastname: Clarke
authors.forename: Jaswinder S
authors.initials: JS
authors.lastname: Samra
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Gill
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D006801:Humans; D007120:Immunochemistry; D019394:Ki-67 Antigen / Q000032:analysis; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000737:chemistry / Q000401:mortality*; D010190:Pancreatic Neoplasms / Q000737:chemistry / Q000401:mortality*; D011379:Prognosis; D017481:Receptors, Somatostatin / Q000032:analysis*; D012189:Retrospective Studies
chemical_list: D019394:Ki-67 Antigen; D017481:Receptors, Somatostatin; C094573:somatostatin receptor 5; C093733:somatostatin receptor 2