CXCL8 and urinary bladder cancer: An initial screen included a bladder cancer panel with 16 proteins (MCP‐1, MIP‐1α, MIP‐1β, IP‐10, IFN‐α, IL‐1α, IL‐1RA, IL‐8, IL‐7, IL‐31, IL‐15, TNF‐β, Eotaxin, SDF‐1α, Rantes, and GRO).