In addition to the prognostically nonbeneficial role of IL-17A in the local microenvironment of CRC, CRC patients could be characterized by an increased frequency of IL-17+ CD4+ T cells in the peripheral blood [73], and increased serum levels of IL-17A in patients with advanced-stage colon tumors have been linked to the reduced tumor infiltration of CD8+ T cells [74]. Here, IL17A is linked to colorectal carcinoma.