Objective To evaluate the screening value of serum pepsinogen (PG) Ⅰ, pepsinogen ratio (PGR, PG Ⅰ/PG Ⅱ) and gastrin 17 (G17) levels combined with gastroscopy for early-stage gastric cancer in high incidence areas of gastric cancer in Qinghai Province. Methods A total of 2 700 cases were identified as the appropriate age (40-69 years) target population through the questionnaire survey from 25 000 local residents in high incidence areas of gastric cancer in Qinghai Province. The serum PGⅠ, PGⅡ and G17 levels of the 2 700 target population were determined by ELISA, and PGR were calculated. And then 949 patients with abnormal levels of PG and G17 were screened out as a high-risk group of gastric cancer to receive gastroscopy and pathologic biopsy. According to the results of gastroscopy and biopsy, the patients were divided into non-atrophic gastritis group, atrophic gastritis group, peptic ulcer group, early-stage gastric cancer group, and advanced gastric cancer group. The optimal threshold and its sensitivity and specificity of serum PG Ⅰ, PGR and G17 levels for diagnosis of early-stage and advanced gastric cancer were determined based on the receiver operator characteristic curve (ROC). ResultsTotally 949 cases received gastroscopy and 649 cases received pathological biopsy, including 239 cases of non-atrophic gastritis, 500 cases of atrophic gastritis, 197 cases of peptic ulcer, 5 cases of early-stage gastric cancer, and 8 cases of advanced gastric cancer. The level of serum PG Ⅰ in the early-stage gastric cancer group (7000±1235 μg/L) and advanced gastric cancer group (3839±277 μg/L) was significant lower than that in the non-atrophic gastritis group (10389±3745 μg/L, both P＜005), and the value of early-stage gastric cancer group was obviously higher than that of advanced gastric cancer group (P＜005). The PGR of the early-stage gastric cancer group (374±140) and the advanced gastric cancer group (205±059) was significantly lower than that in the non-atrophic gastritis group (918±410, both P＜005), and the value of early-stage gastric cancer group was significantly higher than that of the advanced gastric cancer group (P＜005). The level of serum G17 in the early gastric cancer group (1803±452 pmol/L) and the advanced gastric cancer group (2515±376 pmol/L) was significantly higher than that in the non-atrophic gastritis group (1499±712 pmol/L, both P＜005), and the level of early-stage gastric cancer group was significantly lower than that of advanced gastric cancer group (P＜005). According to the analysis of ROC in the diagnosis of early-stage gastric cancer, the best threshold of PG Ⅰ, PGR and G17 was 7185 μg/L, 504, and 1565 pmol/L, respectively, and the corresponding sensitivity and specificity was 800% and 590%, 1000% and 704%, and 800% and 693%, respectively, for PG Ⅰ, PGR and G17. The analysis of ROC in the diagnosis of advanced gastric cancer showd that the best critical value of PG Ⅰ, PGR and G17 was 4255 μg/L, 279 and 2055 pmol/L, respectively, and the corresponding sensitivity and specificity was 1000% and 953%, 1000% and 921%, and 1000% and 897%, respectively. ConclusionUsing serological detection of PG and G17 to screen high-risk group of gastric cancer, and then making diagnosis by gastroscopy and biopsy is an effective, low-cost and non-invasive approach for the early-stage gastric cancer in high incidence areas of gastric cancer in Qinghai Province.