Objective:Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry(SELDI-TOF-MS) is one of the currently used techniques to identify biomarkers for cancers.This study was planned to make a proteomic analysis on the serum of stage I gastric cancer patients and establish a early diagnostic model for identifying stage I gastric cancer preliminarily.Methods:A total of 229 serum samples including 169 pathologically confirmed gastric cancer patients(stage I:n = 47;stage II:n = 39;stage III:n = 46;stage IV:n = 37) and 60 gastritis patients were analyzed by SELDI-TOF-MS Protein Chip array technology.The resulting SELDI-TOF-MS spectral data were analyzed using the Biomarker WizardTM and Biomarker Patterns software to find differential proteins and develop a classification tree for early gastric cancer.Results:Twelve proteins were significantly over expressed(P<0.05,Student t-test) in patients with gastric cancer compared to patients with gastritis.Among them,three protein masses with 2873,6121 and 7778 m/z was found to be differentially expressed solely in patients suffering from stage I gastric cancer.The three protein masses construct the decision tree which could effectively distinguish stage I gastric cancer samples from control samples,achieving a sensitivity and specificity of 89.36(42/47) and 97.32%(182/187),respectively.Conclusion:Serum Proteomic Patterns can be used for the quick diagnosis of stage I gastric cancer.SELDI-TOF-MS is a useful tool for the detection and identification of new protein markers in serum. Objective: Surface-enhanced laser desorption / ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is one of the currently used techniques to identify biomarkers for cancers. This study was planned to make a proteomic analysis on the serum of stage I gastric cancer patients and establish an early diagnostic model for identifying stage I gastric cancer preliminarily. Methods: A total of 229 serum samples including 169 pathologically confirmed gastric cancer patients (stage I: n = 47; stage II: n = 39; : n = 46; stage IV: n = 37) and 60 gastritis patients were analyzed by SELDI-TOF-MS Protein Chip array technology. The resulting SELDI-TOF-MS spectral data were analyzed using the Biomarker Wizard ™ and Biomarker Patterns software to find differential proteins and develop a classification tree for early gastric cancer. Results: Twelve proteins were significantly over expressed (P <0.05, Student t-test) in patients with gastric cancer compared to patients with gastritis. Among them, three protein m asses with 2873,6121 and 7778 m / z was found to be differentially expressed solely in patients suffering from stage I gastric cancer. The three protein masses construct the decision tree which could effectively distinguish stage I gastric cancer samples from control samples, achieving a sensitivity and specificity of 89.36 (42/47) and 97.32% (182/187), respectively.Conclusion: Serum Proteomic Patterns can be used for the quick diagnosis of stage I gastric cancer. SELDI-TOF-MS is a useful tool for the detection and identification of new protein markers in serum.