Immunoediting

Immunoediting is a fundamental process in the immune system's response to cancer, encompassing the dual roles of suppressing tumor growth and shaping tumor immunogenicity. This complex process is divided into three phases: elimination, equilibrium, and escape, collectively known as the 3 Es of immunoediting.

Elimination

The elimination phase, often equated with immunosurveillance, represents the immune system's initial attempt to destroy cancer cells. During this phase, immune cells such as natural killer cells, macrophages, and dendritic cells recognize and kill cancer cells, preventing their proliferation. The effectiveness of this phase is contingent upon the immune system's ability to recognize tumor antigens as foreign.

Equilibrium

The equilibrium phase is a dynamic state in which the immune system controls tumor growth, preventing its expansion but not completely eradicating it. During this phase, the selective pressure exerted by the immune response leads to the survival of tumor cells with reduced immunogenicity. These cells are more adept at evading the immune system, leading to a state of dormancy. The equilibrium phase is critical in shaping the immunogenicity of the tumor, as it selects for cancer cells that can survive in an immunocompetent host.

Escape

The escape phase occurs when the tumor evolves mechanisms to evade the immune system, leading to uncontrolled growth and metastasis. Tumor cells may achieve this through various strategies, including the downregulation of antigen presentation machinery, secretion of immunosuppressive molecules, and induction of regulatory immune cells that inhibit anti-tumor immunity. The escape phase marks the transition of the tumor from being controlled by the immune system to becoming clinically detectable and aggressive.