Abstract: OBJECTIVE To investigate the use of gastroscopic detection of pepsinogen 1 (PGI), pepsinogen 2 (PGII), Helicobacter pylori immunoglobulin G (Hp-IgG) in diagnosis of precancerous lesions and early gastric cancer in high-risk groups, in order to provide a theoretical basis for the early diagnosis and prevention of gastric cancer. METHODS Totally 95 middle-aged and elderly patients who were diagnosed with gastric cancer after pathological examination in Juye County People's Hospital of Shandong Province from Jan. 2015 to Mar. 2018 were selected as the gastric cancer group, and 225 middle-aged and elderly patients with precancerous lesions were included, among which 117 patients with atrophic gastritis were set as atrophy group and 108 patients with benign gastric cancer, ie, superficial gastritis, were set as superficial group. Meanwhile, 69 patients who underwent healthy physical examination in our hospital were as the control group. The clinical expression levels of PGI, PGII and PGR in the four groups were statistically analyzed. The positive rate of Hp-IgG in the four groups was observed. The relationship between Hp-IgG positive and expression levels of PGI, PGII and PGR in patients of the gastric cancer group and the atrophy group was observed. The specificity and sensitivity of Hp-IgG alone, PGI alone, PGII alone, and combined detection of these three indicators were statistically analyzed. RESULTS The expression levels of PGI and PGR in the gastric cancer group were (55.59±18.64) μg/L and (3.62±1.37) μg/L, respectively, which were significantly lower than those of the atrophy group, the superficial group and the control group (P<0.05). The expression level of PGII was (20.95±4.05) μg/L, significantly higher than those in the atrophy group, superficial group and the referencecontrol group (P<0.05). The expression levels of PGI and PGR in the atrophy group were significantly lower than those in the superficial group and the control group (P<0.05). The positive rate of Hp-IgG in patients with gastric cancer was 90.5%, which was significantly higher than 65.8% in the atrophy group and 48.1% in the superficial group (P<0.05). The positive rate of Hp-IgG in the atrophy group was significantly higher than that in the superficial group (P<0.05). The expression levels of PGI and PGII in the Hp-IgG positive patients of the atrophic group were significantly higher than those in the Hp-IgG negative patients of the same group (P<0.05). For the diagnosis of gastric cancer, the specificity of the combined detection of the three indicators was 0.874, and the sensitivity was 0.769, which were significantly higher than those of the three indicators alone (P<0.05). CONCLUSION The combined use of PGI, PGII, and Hp-IgG in gastroscope detection has high specificity and sensitivity in the diagnosis of gastric precancerous lesions and early gastric cancers in high-risk populations.