Chromogranin A as a determinant of midgut carcinoid tumour volume.

Neuroendocrine (NE) tumours are characterized by their capacity to synthesize, store and release hormonal products. These substances are stored in neurosecretory vesicles together with chromogranin A (CgA). The concentration of plasma CgA in patients with NE tumours is thought to reflect the degree of NE differentiation, total tumour burden and effect of medical treatment. The aim of this study was to analyse the correlation between tumour weight and plasma CgA levels as well as the influence of treatment with a long-acting somatostatin analogue (octreotide) using nude mice with xenografted human ileal carcinoid tumours. There was a correlation between tumour weight and plasma CgA levels in all animals (p < 0.00001). In octreotide-treated mice, plasma CgA levels were significantly reduced versus untreated animals (p = 0.037). In conclusion, this study demonstrates that plasma CgA levels are closely correlated to tumour burden, and that plasma CgA is well suited for monitoring the clinical course and outcome of treatment in patients with NE tumours.