Malignant tumors of the digestive system , with high morbidity and mortality rate , are insidious at the onset and lack of effective treatments so far .Interleukin-22 (IL-22) is one of the members of the IL-10 cytokine family discovered in recent years and was originally called IL-10-associated T cell differentiation inducing factor (IL-TIF).IL-22 expression is elevated in various digestive system malignant tumors, and increased IL-22 expression is associated with tumor progression and poor prognosis .Studies on the molecular mechanism revealed that IL-22 initiates a series of downstream signaling pathways such as JAK/STAT and MAPK, by acting on the IL-22 receptor, inducing tumorigenesis.IL-22 is expected to be a novel diagnostic biomarker and therapeutic target of digestive system malignant tumor .