This lecture delves into the experimental evidence supporting the immunoediting of tumors, showcasing how the immune system can recognize and respond to tumors, leading to elimination, equilibrium, or escape. It discusses the roles of immune cells in cancer, the mechanisms through which tumors escape immune pressure, and the impact of tumor-derived immunosuppressive factors. The lecture also explores the use of immunotherapy, such as checkpoint inhibitors, to counteract tumor immune evasion strategies and enhance antitumor immune responses.