IL17A and esophageal squamous cell carcinoma: We first detected tumor-infiltrating-IL-17 producing cells in human esophageal squamous cell carcinoma (ESCC) and observed that the levels of IL-17 producing cells correlated inversely with T (depth of primary tumor invasion, P = 0.042), indicating that enriched IL-17 producing cells in the tumor microenvironment may inhibit tumor invasion.