Although chromogranin A (CGA) is a useful marker for pancreatic neuroendocrine 
tumors (pNET) in the West, its usefulness in Japanese populations is unclear. To 
assess this, we evaluated the serum CGA levels in 189 patients with various 
pancreatic diseases, including proven pNET (n = 69), pancreatic cancer (PC) (n = 
50), chronic pancreatitis (CP) (n = 50) and autoimmune pancreatitis (AIP) (n = 
20), and 112 normal controls (controls) using an ELISA kit. The mean CGA level 
of patients with pNET was significantly higher than any of the other groups 
(407.8 ± 984.6 ng/mL [pNET] vs 91.8 ± 101.8 ng/mL [PC], 93.6 ± 57.5 ng/mL [CP], 
69.9 ± 52.4 ng/mL [AIP] and 62.5 ± 48.3 ng/mL [controls]). Limiting the analysis 
to patients not using proton pump inhibitors (PPI), the CGA level of patients 
with PC or CP was not significantly different compared with the controls. 
Discriminant analysis revealed that the best cut-off value of CGA to distinguish 
patients with pNET from the controls was 78.7 ng/mL, with a sensitivity and 
specificity of 53.6% and 78.6%, respectively. In patients with pNET, significant 
factors associating with elevated CGA levels were tumor classification, tumor 
size, and the presence of liver metastases in univariate analysis as well as PPI 
use and the presence of liver metastases in multivariate analysis. We show that 
CGA is a useful marker for diagnosing pNET in Japanese populations and for 
distinguishing patients with pNET from patients with other pancreatic diseases. 
The increased use of CGA in Japan will likely be a helpful tool in managing 
these patients, as found in the West.