Gene set enrichment analysis was conducted to study the relevant mechanisms.Bladder cancer patients in COL5A2 low expression group were associated with better invasiveness (P < .0001), tumor grade (P = .001), T staging (P < .0001), N staging (P = .002), cancer specific survival (P < .0001), overall survival (P < .0001), and a trend of better M staging (P = .053) than those in COL5A2 high expression group.COL5A2 might affect the progression of bladder cancer through "Coagulation," "Hypoxia," "Apical junction," "Ultraviolet response," "Epithelial mesenchymal transition," "Angiogenesis," "KRAS (KRAS proto-oncogene, GTPase) signaling,"Complement,"IL2-STAT5-signaling," "Inflammatory response," "IL6-JAK-STAT3-signaling," "Myogenesis," "TNF α signaling," "Apoptosis," and "Hedgehog-signaling.