Compared with non-metastatic GC, the concentration of sE-CAD in mGC before any treatment increased in HER2-negative cases (n = 49; median 4885 pg/mL, p < 0.05) and much more in HER2–positive cases (n = 6, median 6001 pg/mL, p < 0.05) (Supplementary Figure S2). This evidence concerns the gene ERBB2 and gastric cancer.