The IL-17 family of cytokines is composed of six members named IL-17A (commonly known as IL-17), IL-17B, IL-17C, IL-17D, IL-17E (also known as IL-25), and IL-17F with different sequence homology and functions that are important players in host defense responses, inflammation, and cancer development [46,47,48]. The gene discussed is IL17D; the disease is cancer.