Serum concentration and expression of Reg IV in patients with esophageal cancer: Age-related elevation of serum Reg IV concentration.

Regenerating islet-derived family, member 4 (REG4, which encodes Reg IV) is a marker for cancer and inflammatory bowel disease. This study aimed to investigate the diagnostic utility of Reg IV measurement in sera from esophageal cancer patients. Reg IV expression was examined in 269 esophageal cancer samples by immunostaining and the Reg IV levels in sera were measured from 65 patients with esophageal squamous cell carcinoma (SCC) by enzyme-linked immunosorbent assay. No Reg IV staining was detected in 255 SCC and 4 small cell carcinoma samples, whereas Reg IV was stained in 4 of 10 (40%) adenocarcinoma samples. Serum Reg IV concentration in esophageal SCC patients was significantly higher compared to that of the control subjects (P=0.0003). A significant correlation between serum Reg IV concentration and age was found in control subjects (P<0.0001). When serum Reg IV concentration was analyzed according to age, the distribution of serum Reg IV concentration in patients with esophageal SCC was similar to that of the control subjects. These results suggest that Reg IV expression is highly specific for adenocarcinoma of the esophagus. Further investigation is required to clarify whether Reg IV serves as a serum tumor marker for esophageal cancer.