Nuclear PSMB8 expression was associated with increased invasiveness of gastric adenocarcinoma, including higher stage (P < 0.0001), depth of invasion (P = 0.003), lymph node metastasis (P < 0.0001), lymphovascular tumor emboli (P < 0.0001), increased tumor size (P = 0.002), and perineural invasion of tumor cells (P = 0.040). This evidence concerns the gene PSMB8 and gastric adenocarcinoma.