A Novel Index Including Age, Sex, hTERT, and Methylated RUNX3 Is Useful for Diagnosing Early Gastric Cancer

Introduction: As the incidence of gastric cancer (GC) is increasing in East Asia including Japan, a simple blood test for early GC is needed as an alternative to upper gastrointestinal (UGI) endoscopy. We performed this study to address this issue. Methods: We collected serum samples from 319 participants comprising 225 healthy subjects without GC (control group) and 94 patients with early GC (early GC group). After evaluating copy numbers of serum hTERT and methylated RUNX3 (m-RUNX3) using the combined restriction digital PCR (CORD) assay, which we developed, we assessed the diagnostic performance of hTERT and m-RUNX3 for early GC. Results: Serum levels of hTERT and m-RUNX3 were significantly higher in the early GC group than in the control group. The area under the curve (AUC) was 0.89 for hTERT and 0.78 for m-RUNX3. Multivariate logistic regression analysis revealed age, sex, hTERT copy number, and m-RUNX3 copy number to be independent factors for early GC. We then established a prediction formula and named it the ASTEm-R3 (Age, Sex, hTERT, and m-RUNX3) index. The AUC of the ASTEm-R3 index was 0.93 with a sensitivity of 79.7% and specificity of 91.1%. Conclusion: We demonstrated excellent performance of the ASTEm-R3 index using the CORD assay to detect early GC. This index might be a promising alternative to UGI endoscopy.