Numerous studies have demonstrated that IL-33 plays dual roles regulating tumor transformation, growth, and metastasis in many cancers, including non-small cell lung cancer (NSCLC), colorectal cancer, gastric cancer, pancreatic tumor, and breast cancer by directly acting on tumor cells or by indirectly affecting immune cells or the tumor microenvironment [219,220,221,222,223,224]. Here, IL33 is linked to cancer.