IL17A and neoplasm: Among Tregs, the phenotype CD4 + Foxp3 + cells inhibit tumor growth in AOM/DSS models, IL17 + Foxp3 + CD4 + T cells are present in higher concentrations in IBD patients, while Foxp3 + RORγt + T cells potentially aid in tumor progression through the secretion of IL-17, favoring an inflammatory microenvironment, and have a greater capacity to inhibit the cytotoxic response of CD8 + lymphocytes, thereby preventing the elimination of transformed cells [57–59] (Fig. 1A).