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Medline ® Abstract for Reference 40

of 'Metastatic well-differentiated gastroenteropancreatic neuroendocrine tumors: Presentation, prognosis, imaging, and biochemical monitoring'

Chromogranin-A as a serum marker for neuroendocrine tumors: comparison with neuron-specific enolase and correlation with immunohistochemical findings.
Giovanella L, La Rosa S, Ceriani L, Uccella S, Erba P, Garancini S
Int J Biol Markers. 1999;14(3):160.
BACKGROUND: Chromogranin-A (Cg-A) is a 439-amino-acid protein contained in secretory granules of neuroendocrine cells, in addition to specific hormone peptides or neuropeptides. Since Cg-A is co-released with peptide hormones its serum concentration can be used as a marker of neuroendocrine tumors.
AIM: Evaluation of the analytical performance of a new IRMA method for Cg-A assay and of the clinical value of serum Cg-A and neuron-specific enolase (NSE) in neuroendocrine tumors. In addition, we compared the diagnostic usefulness of both Cg-A and NSE serum levels and their relationship to tissue expression.
PATIENTS AND METHODS: Initially we evaluated the analytical performance (intra- and interassay imprecision, dilution test and detection limit) of the Cg-A RIACT method (CIS Bio-International, Gif-sur-Yvette, France). We selected 50 patients affected by various histologically confirmed neuroendocrine tumors (NETs): 111In-pentetreotide scan and helical computed tomography were employed to assess tumor extent. Cg-A and NSE were measured before surgery inserum samples of patients and 50 age-matched controls by IRMA methods. After surgery immunohistochemical stains for Cg-A and NSE were performed on surgical specimens of tumor tissue.
RESULTS: Cg-A levels were significantly higher (p<0.0001) in patients with NETs than in healthy controls and we found a positive correlation between serum and tissue expression (p<0.05). Serum levels of Cg-A were also related to tumor extent (p<0.05) but in some cases we observed significant elevation of serum Cg-A in small, intensely immunoreactive NETs. ROC curve analysis showed better accuracy for serum Cg-A compared to NSE in the diagnosis of NETs, while no significant relationship was found between serum expression and immunostaining for NSE.
DISCUSSION: Our results confirmed the biological and clinical significance of circulating Cg-A as an expression of granular content in neuroendocrine tissues and supported the complementary usefulness of serum Cg-A in the diagnosis and evaluation of NETs together with imaging modalities.
Department of Nuclear Medicine, University Hospital Ospedale di Circolo e Fondazione Macchi, Varese, Italy.