Although the sensitivity and specificity of circulating miRNA biomarkers for GC detection are much higher than that of the serum biomarkers (CA19-9 and CEA) currently used, it is a long way to go before circulating miRNAs as a clinical diagnosis are used to detect GC, because the levels of a circulating miRNA might be significantly higher or lower in various diseases. The gene discussed is CEACAM5; the disease is gastric cancer.