CGA and hereditary pheochromocytoma-paraganglioma: Since 1984, when O’Connor DT et al. [46] first measured the circulating CgA in a patient with pheochromocytoma by the immunoassay method and demonstrated that CgA might be a potential biomarker of this tumor, many studies have evaluated its clinical impact in various neuroendocrine tumors [16–18, 47–49].