Although IL-18 is perceived as an anticancer cytokine, high concentrations of IL-18 have been associated with advanced tumor stages in patients with seven tumor types (pancreatic cancer, esophageal squamous cell carcinoma, breast cancer, hepatocellular carcinoma, lung cancer, renal cell carcinoma, multiple myeloma, and oral cavity cancer) [5, 6]. Here, IL18 is linked to breast cancer.