Th17 cells are specifically accumulated in many types of human tumors.473 Cytokine milieu formed by IL-1β, IL-6, IL-23, and TGF-β produced by tumor cells, CAFs and tumor-associated macrophages (TAMs) supports Th17 cell differentiation and expansion.474,475 However, the effects of Th17 cells and cytokine IL-17 on tumor immunity are contradictory.473,476 Therefore, the presence of Th17 cells is associated with either good or poor prognosis depending on tumor types477–479 (Table 2). This evidence concerns the gene IL23A and neoplasm.