BACKGROUND: Pancreatic neuroendocrine tumors (PNETs) are a group of rare tumors. 
Chromogranin A (CgA) was considered as the most practical and useful serum tumor 
marker in PNET patients. But peripheral blood levels of CgA are not routinely 
tested in Chinese patients with PNETs. This study was to assess the diagnostic 
value of CgA in Chinese patients with PNETs especially in patients with 
insulinomas.
METHODS: Eighty-nine patients with PNETs including 57 insulinomas and 32 
non-insulinoma PNETs as well as 86 healthy participants were enrolled in this 
study between September 2003 and June 2013. Serum levels of CgA were measured by 
ELISA method. Expression of CgA protein was detected in 26 PNET tissues 
including 14 insulinomas by immunohistochemical staining.
RESULTS: Serum levels of CgA in 89 PNET patients were significantly higher than 
that in healthy controls (P = 7.2 × 10-9). Serum levels of CgA in 57 patients 
with insulinomas (median 64.8 ng/ml, range 25-164) were slightly higher than the 
levels in healthy controls (median 53.4 ng/ml, range 39-94) but much lower than 
the levels in 32 patients with non-insulinoma PNETs (median 193 ng/ml, range 
27-9021), P = 0.001. The serum CgA levels were reduced in 16 of 17 patients with 
insulinomas after tumor resection. ROC curve showed that CgA values at 60 ng/ml 
distinguished patients with insulinomas from healthy controls but its 
sensitivity and specificity were 66.7% and 73.3%, respectively. In contrast, CgA 
values at 74 ng/ml distinguished patients with non-insulinoma PNETs from healthy 
controls, and the sensitivity and specificity were 65.6% and 91.9%, 
respectively. Except for two insulinomas with negative staining of CgA, 12 
insulinoma tissues showed positive staining of CgA.
CONCLUSION: CgA is a reliable serum diagnostic biomarker for PNETs but not for 
insulinomas.