IL17A and neoplasm: 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).