ALDH1A1 and gastric cancer: Through the detection of G-17 level and ALDH1 level in gastric juice of control group, CAG group, GU group and GC group, this study proved that G-17 level and ALDH1 level in gastric juice of gastric cancer group were significantly increased, which confirmed the high diagnostic value of G-17 and ALDH1 in the diagnosis of gastric cancer.