Study of the gastroenteropancreatic neuroendocrine tumor (gep-net) microenvironment beyond angiogenesis: The role of lysyl oxidase-like 2 (LOXL2).

4109 Background: A better understanding of the tumour microenvironment beyond angiogenesis of this heterogeneous group of malignancies remains a challenge. In this study, we present an exploratory analysis of the microenvironment protein expression and its relation with prognosis and previously described biomarkers. Methods: Formalin-fixed and paraffin embedded samples (FFPEs) of patients (pts) who underwent surgery for gep-net and their clinical data were collected consecutively from 1980 to 2012.Tissue microarrays were constructed from non-necrotic areas of tumour foci. Microenvironment related proteins (LOXL2, LOX, CXCR4, TWIST, β-catenin and E-cadherin) were studied by inmunohistochemistry and compared to the expression of SSTR2, ATRX and members of the mTOR pathway. The study was approved by the local Ethic Committee. Univariate (UVA) and multivariate analysis (MVA) was performed. Kaplan- Meier method, log rank test and cox regression was used to study disease free survival (DFS) and overall survival...