 Although gastroenteropancreatic neuroendocrine neoplasia GEP-NEN were considered for years as rare tumors, their incidences are increasing. Due to their potential of early metastases and their heterogenous response to therapy, these tumors are important clinical entities. A major problem remains the impossibility to adequately predict tumors response to treatment, precluding an individualized therapy. Further, there is no method to efficiently screen these tumors. Protein based analyses proteomic analyses gain in interest as methods to address this problematic. 