OBJECTIVES: The objectives of this study were to examine the whole-serum N-glycan profile of patients with unresectable pancreatic cancer and to evaluate the ability of glycans to predict gemcitabine treatment efficacy and patient survival. METHODS: We collected serum from 52 patients with advanced pancreatic cancer before they began gemcitabine monotherapy. The serum glycan profile was measured through comprehensive quantitative high-throughput glycome analysis and compared with the treatment efficacy and patient survival. RESULTS: Of the 61 glycans detected, the serum levels of glycan 4310 (molecular weight [m/z] 1549.566), 6301 (m/z 2032.724), and 9200 (m/z 2010.692) were high in patients with a short time to tumor progression (TTP). Multivariate analysis revealed that a high glycan 9200 concentration was an independent risk factor for shorter TTP (hazard ratio, 2.11; 95% confidence interval, 1.07-4.17) and poor overall survival (hazard ratio, 2.56; 95% confidence interval, 1.08-6.19). The median TTP of patients with up-regulation of 9200 after gemcitabine treatment was shorter than for the remaining patients (91 vs 301 days; P = 0.0005). A similar relationship was observed for overall survival (median, 181 vs 561 days; P = 0.001). CONCLUSIONS: Glycan 9200 is a possible biomarker predicting gemcitabine efficacy survival in patients with unresectable pancreatic cancer.