Circulating chromogranin A in the assessment of patients with neuroendocrine tumours. A single institution experience.

BACKGROUND: Chromogranin A (CgA) is a secretory protein present in dense-core vesicles of neuroendocrine (NE) cells. Its ubiquitous presence in NE tissues makes it a suitable circulating marker of neoplasms of NE origin. PATIENTS AND METHODS: Plasma CgA was determined in 178 patients with NE tumors and in 36 patients with non-endocrine malignancies. Circulating CgA was also serially evaluated in 39 NE cancer patients with advanced disease submitted to systemic therapy and in 14 patients with no evidence of disease (NED).
RESULTS: Supranormal CgA values were found in 81% of patients with advanced NE tumors and in only 91% of NED cases. Plasma CgA in patients with well differentiated NE tumors, such as carcinoids, carcinoma of gastrointestinal tract, pheocromocytoma, pancreatic NE carcinoma (either functioning or not functioning), medullary thyroid carcinoma and NE tumors from various primary sites, was higher and more frequently elevated than in patients with small-cell lung cancer (P < 0.001). Plasma CgA did not discriminate patients with NE from those with non NE neoplasms since it was found elevated in 44% of the latter cases. Plasma CgA pattern correlated with the disease response in patients submitted to cytotoxic treatment and with changes in clinical symptomathology in patients receiving somatostatin analogs.
CONCLUSIONS: Our data confirm that CgA is the best circulating neuroendocrine marker available up to now available for the management of differentiated neuroendocrine malignancies irrespective of tumor location and functional status. CgA plasma levels could also identify the coexistence of neuroendocrine differentiation in the context of non-endocrine malignancies. Circulating CgA seems to be less useful in undifferentiated tumors such as small-cell lung cancer.