Evaluation of REG4 for early diagnosis and prognosis of gastric cancer

We explored the correlation between the development of gastric cancer and the concentration of REG4 and hence the suitability of REG4 as an indicator of the prognosis of patients with GC. Real-time polymerase chain reaction was conducted to detect REG4 messenger RNA expression. The amount of the REG4 protein was measured by immunohistochemistry staining of tissue and enzyme-linked immunosorbent assay of serum. Serum carcinoembryonic antigen and carbohydrate antigen 19-9 concentrations were measured using a commercial automated immunoassay. Real-time polymerase chain reaction results confirmed that REG4 was significantly up-regulated in gastric cancer compared with paired normal mucosa (P < .001). Immunohistochemistry staining revealed that high expression of REG4 correlated with diffuse type, poor differentiation, lymph node metastasis, distant metastasis, and TNM stage III or IV. The mean survival time for patients in the REG4-positive group was significantly less than that in the REG4-negative group (P = .013). The percentage of serum samples that were REG4 positive was 44.0%, which was higher than that for serum carcinoembryonic antigen (P = .039) or carbohydrate antigen 19-9 (P = .012) in TNM stage I and was significantly higher (P = .031) than that in TNM stage II. Thus, REG4 may be not only a prognostic indicator but also a better serum marker than carcinoembryonic antigen and carbohydrate antigen 19-9 for early diagnosis of gastric cancer. (C) 2011 Elsevier Inc. All rights reserved.