The model does not account for cancer-associated fibroblasts (CAFs), which have a pro-tumorigenic activity by secretion of pro-cancer cytokines, such as IFN-γ, which polarize and strengthen the cancer against anti-tumoral stimuli [27], growth factors, such as HGF [28], extracellular remodelling that inhibits T cell infiltration [29, 30]. This evidence concerns the gene IFNG and cancer.