Tumour immune editing:
Tumour immune surveillance is the process by which immune cells detect and eliminate malignantly transformed cells. While this surveillance is very effective and eliminates most arising tumour cells, some tumour cells can escape and survive. The immune system can repress the growth of these escaped cells by creating a restrictive microenvironment where the tumour cells persist, usually as dormant cells. Tumour immune suppression may however fail or become exhausted, allowing unrestricted growth of the tumour cells. This evolving tumour-immune interaction is referred to as tumour immune editing.
Tumour immune editing consists of three phases. The elimination phase is where the immune system can recognise cancer cells and can launch an effective cytotoxic reaction against them. The equilibrium phase is where the immune system and the tumour reaches a steady state equilibrium, where the tumour persists but does not grow in size. However in this phase, some tumour cells may proliferate and/or gain new characteristics that help them to become undetectable to the immune system, block activation of the immune cells or develop resistance mechanisms against immune-mediated cytotoxicity. When tumour cells develop a non-immunogenic phenotype by gaining some of the above characteristics, or if the immune system becomes exhausted, tumour growth is no longer repressed and the tumour will manifest (escape phase).