  In the tumour microenvironment, cancer cells directly interact with both the
immune system and the stroma. It is firmly established that the immune system,
historically believed to be a major part of the body's defence against tumour
progression, can be reprogrammed by tumour cells to be ineffective,
inactivated, or even acquire tumour promoting phenotypes. Likewise, stromal
cells and extracellular matrix can also have pro-and anti-tumour properties.
However, there is strong evidence that the stroma and immune system also
directly interact, therefore creating a tripartite interaction that exists
between cancer cells, immune cells and tumour stroma. This interaction
contributes to the maintenance of a chronically inflamed tumour
microenvironment with pro-tumorigenic immune phenotypes and facilitated
metastatic dissemination. A comprehensive understanding of cancer in the
context of dynamical interactions of the immune system and the tumour stroma is
therefore required to truly understand the progression toward and past
malignancy.
