CRC: A Darwinian model of cellular immunoselection

It is widely accepted that the presence of immune infiltrate in human tumors is considered as an attempt of the host immunosurveillance to detect and eliminate tumor cells in order to prevent tumor progression. However, the interaction of the immune system with the tumor is much more complex and highlights the controversial roles that play innate and acquired immunity in the tumor microenvironment. On the one hand, they inhibit tumor growth and dissemination, but on the other, promote cancer progression. Numerous evidences indicate that the chronic inflammatory response in the tumor microenvironment becomes a key process that polarizes immunity toward a phenotype that promotes tumor development. But, in addition, the intense immunosurveillance by the host immune system favors the selection of tumor variants with altered phenotype and reduced immunogenicity, facilitating the escape from the immune system.