Serum chromogranin–а levels in neuroendocrine neoplasms as prognostic marker in correlation with the clinical course of the disease and the influence of octreotid therapy

Neuroendocrine neplasms (NEN) arise from neuroedocrine cells in various tissues and organs, have diverse biological behavior and express neuroendocrine markers synaptophysin and chromogranin A (CgA). The aim of this study was to correlate the serum CgA levels before and after surgical and/or oncological treatment with octreotide and to determine the prognostic value of CgA variations during the follow-up. We used ELISA to analyze 699 serum samples from 410 patients during 9 years, due to carcinoid syndrome, benign neuroendocrine tumor (NET), localized neuroendocrine carcinoma (NEC) and patients with metastatic NEC (MS). Data from hospital databases were used for follow-up of 60 patients, divided into responders and non-responders, regarding their response to therapy. The mean serum CgA value in 410 analyzed patients was by 3.47-fold increase compared to the maximal reference values. The highest increase was measured in patients with NEC/MS, with mean 12.94-fold increase, followed by patients with localized NECs, with mean 4.57. During follow-up, CgA values were reduced, with a significant difference between the groups of responders and non-responders. Reduction of the CgA level for at least 49.5% during the first 12 months after therapy was correlated with stable disease course, and serum CgA elevation or decrease less than 34% during the first 12 months after the therapy was correlated to unfavorable clinical course. Serum CgA levels are useful for the diagnosis of NENs and during the follow-up for detection of recurrence, disease progression and evaluation of the oncologic therapy response.