Gastric cancer is the sixth leading cause of cancer‐related death in Taiwan, and the identification of related factors is essential to increase patient survival. ADP‐ribosylation factor 1 (ARF1) was initially identified using 2‐D electrophoresis combined with MALDI–time‐of‐flight mass spectrometry. ADP‐ribosylation factor 1 belongs to the Ras superfamily or GTP‐binding protein family and has been shown to enhance cell proliferation. In the current study, we evaluated the potential of ARF1 as a biomarker for gastric cancer detection. ADP‐ribosylation factor 1 mRNA was upregulated in tumor tissues (compared with adjacent non‐tumor tissues, n = 55) in approximately 67.2% of gastric cancer patients. Expression of ARF1 protein was additionally observed using Western blot and immunohistochemistry (IHC) analyses. The clinicopathological correlations of ARF1 were further evaluated. Elevated ARF1 expression was strongly correlated with lymph node metastasis (P = 0.008), serosal invasion (P = 0.046), lymphatic invasion (P = 0.035), and pathological staging (P = 0.010). Moreover, the 5‐year survival rate for the lower ARF1 expression group (n = 50; IHC score
