Immunology and the Immune Response to Cancer

Tumor Immunoediting: Elimination, Equilibrium, and Escape Phases

The immune system plays a crucial role in recognizing and eliminating cancer cells. Tumor immunoediting is a dynamic process consisting of three phases: elimination, equilibrium, and escape.

Elimination Phase

During this phase, the immune system detects and destroys tumor cells using cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, and macrophages. Inflammatory cytokines such as interferon-gamma (IFN-γ) enhance immune-mediated tumor destruction.

Equilibrium Phase

If some tumor cells evade elimination, they enter the equilibrium phase, where immune surveillance keeps their growth in check. CD8+ T cells and cytokines like transforming growth factor-beta (TGF-β) help maintain this balance.

Escape Phase

Over time, tumor cells may develop immune resistance, leading to the escape phase. These cancer cells evade immune attack through mechanisms such as downregulating major histocompatibility complex (MHC) expression or secreting immunosuppressive factors.

Clinical Implications

Understanding tumor immunoediting is essential for developing immunotherapies, including immune checkpoint inhibitors and adoptive cell therapy.