Novel insight into the role of immunotherapy in gastrointestinal cancer (Review)

To date, great progress has been made in studying the immunology of cancer and the development of immunotherapies. Immunotherapy has become an effective clinical strategy for cancer treatment in courtesy of its unique features. It has been demonstrated to delay tumor progression, reduce tumor recurrence and metastasis, and even cure tumors through enhancing the immune response, stimulating tumor-specific immunity and breaking immune tolerance. Several different immunotherapeutic approaches and methods are in the process of being developed, including the use of cytokines, immune checkpoint inhibitors, engineered T cells (such as T-cell-receptor T cells and chimeric antigen receptor T cells) and cancer vaccines. Digestive system neoplasms pose a serious threat to human health, including esophageal cancer, gastric cancer and colorectal cancer, and immunotherapy is considered to be a promising new avenue for the treatment of digestive system neoplasms. However, certain challenges remain in terms of the broad implementation of immunotherapies due to the incompletely understood mechanisms underlying tumorigenesis. Therefore, it is crucially important to understand both the various different types of immunotherapy and the immune landscapes in digestive system neoplasms in order to reduce the side effects associated with these therapies. The present review discusses existing and newly emerging immunotherapeutic methods that may be applied in the treatment of digestive system neoplasms and how their clinical efficacy may be enhanced.