IL17A and colorectal carcinoma: In 2014, the first evidence emerged purporting that tumor-infiltrating γδ T cells producing IL-17 (hereafter: γδ T17), but not T helper17 (Th17) or cytotoxic T cells producing IL-17 (Tc17), are the major IL-17A (hereafter: IL-17)-producing cells in human CRC [58].