IL-17 cytokines have important roles in innate immunity, as they protect against fungal and bacterial infections, and have a role in tissue healing (Lai et al., 2012; Lee et al., 2015; Maxwell et al., 2015; Bunte and Beikler, 2019; Chen et al., 2019), but these host-protective functions can also cause give rise to immunopathology in autoimmunity, cancer, and other inflammatory diseases (McGeachy et al., 2019). Here, IL17A is linked to cancer.