Objectives: This study was conducted to determine the prognostic value of the Glasgow Prognostic Score (GPS), an inflammation-based prognostic score composed of C-reactive protein and albumin, for patients with advanced cancer. Methods: A total of 83 advanced gastric cancer patients receiving biweekly docetaxel/S-1 treatment (DS) were included in the study. To identify the value of GPS as prognostic factor for disease-specific survival (DSS) and progression-free survival (PFS), univariate and multivariate analyses were performed. Results: Unresectable tumors were observed in 78 patients and recurrent tumors were detected in 5 patients. Of these, 12 patients underwent gastrectomy. There were significant correlations between the GPS and the neutrophil/lymphocyte ratio. Univariate analysis revealed that the GPS, Eastern Cooperative Oncology Group performance status and gastrectomy after DS treatment significantly affected prognosis. Multivariate analysis showed that the GPS, age and gastrectomy independently influenced DSS, and that the GPS and gastrectomy also influenced PFS. Multivariate analysis restricted to patients without gastrectomy showed that the GPS and age independently affected DSS, and that the GPS influenced PFS. Conclusion: In the low GPS group, it may be possible to obtain favorable outcomes by chemotherapy in advanced gastric cancer patients. However, a well-designed prospective trial in a large patient cohort is required to corroborate the prognostic value of the GPS.