Serum chromogranin A for the diagnosis of gastroenteropancreatic neuroendocrine neoplasms and its association with tumour expression.

The aim of the present study was to assess the clinical value of serum chromogranin A (CgA) levels in patients with gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) and to compare them with tumour expression of CgA. A total of 109 consecutive patients with confirmed GEP-NENs were enrolled in this prospective study between December 2012 and August 2016, including 73 patients with primary or recurrent GEP-NENs and 36 patients with GEP-NENs that were treated following surgery. Furthermore, 30 patients with benign gastrointestinal diseases and 30 healthy volunteers served as control groups. Serum CgA levels were measured by ELISA, using different reference values, in order to evaluate its diagnostic efficacy. Serum neuron-specific enolase was also measured to evaluate its diagnostic efficacy and analyse its association with serum CgA levels. The levels of CgA, synaptophysin and neural cell adhesion molecule 1 in the tumour tissue were assessed by immunohistochemical assays. The results indicated that serum CgA levels were significantly higher in patients with GEP-NENs compared with the control groups (P<0.05). No association was observed between serum CgA levels and tumour grade (G1, G2 and G3), but serum CgA levels differed significantly between patients with GEP-NENs of different origins (P<0.05). A serum CgA cut-off value of 85.3 ng/ml was associated with high sensitivity (64.4%) and specificity (92.7%). Different reference values were recommended for NENs of different origins, with serum CgA cut-off values of 96.72, 51.13 and 86.19 ng/ml for the stomach, intestines and pancreas, respectively. The serum CgA levels were consistent with the CgA expression in the tumour. In conclusion, serum CgA may serve as a circulating pathological biomarker for the diagnosis of GEP-NENs. The use of different reference values for different tumour origins may improve the diagnostic efficacy of CgA for GEP-NENs. A cut-off value of 85.3 ng/ml is recommended in the Chinese population.