IL-33 enhances murine breast cancer growth and metastasis by increasing the intratumoural accumulation of immunosuppressive and innate lymphoid cells.26 Higher serum levels of IL-33 were found to be a worse prognostic marker in gastric cancer and in non-small-cell lung carcinoma patients.27, 28 From these observations, IL-33 appears to promote tumour malignancy by modulating Th2-type immunity. Here, IL33 is linked to breast cancer.