Circulating angiopoietin-2 is elevated in patients with neuroendocrine tumours and correlates with disease burden and prognosis

Abstract
Angiogenesis is an essential process in the development and growth of tumours. There are a large number of angiogenic mediators including the angiopoietin (Ang) family and vascular endothelial growth factor, which play an important role in both physiological and pathological angiogenesis. This study examines serum levels of Ang-1 and Ang-2 in patients with neuroendocrine tumour (NET) compared healthy controls. ELISA for Ang-1 and Ang-2 was performed in 47 patients with histologically proven NETs and 44 healthy controls. Immunohistochemical staining for Ang-2 was performed in patients to demonstrate cellular location of Ang-2. Serum Ang-2 levels were significantly elevated in patients compared controls (median 4756 vs 2495 pg/ml, PP4756 pg/ml (P=0.04). Serum Ang-2 but not Ang-1 is elevated in NET patients. Ang-2 may be a useful serum marker for monitoring and assessment of prognosis in patients with NETs.