Chromogranin A: an additional tumor marker for postoperative recurrence and metastases of medullary thyroid carcinomas?

In this study, plasma concentrations of chromogranin A, calcitonin and carcinoembryonic antigen (CEA) were measured in 40 healthy volunteers as well as in 129 patients with recurrences and/or metastases of neuroendocrine tumors and of medullary thyroid carcinomas (MTCs). A double antibody assay was employed using polyclonal rabbit antibodies to a C-terminal fragment of the protein for detection of human chromogranin A. Using ROC analysis, a cutoff at 22 U/l chromogranin A was calculated. In patients with neuroendocrine tumours, much higher serum concentrations of chromogranin A than for patients with MTC (80% vs. 46%) were measured. The following sensitivities were found: chromogranin A; 46%, calcitonin 100%, CEA 52%. Furthermore, the mean values of chromogranin A concentrations correlated with the tumour mass and/or number of metastases in MTC and neuroendocrine tumours. Evaluation of follow-up studies remains to be completed; however, preliminary results showed similarities regarding the behaviour of chromogranin A and calcitonin. Despite the findings of this study, the observations could not confirm chromogranin A as a reliable marker for metastazing or recurrent MTC.