Tumor microenvironment

The tumor mass consists not only of a heterogeneous population of cancer cells but also a variety of resident and infiltrating host cells, secreted factors and extracellular matrix proteins, collectively known as the tumor microenvironment.

The tumor microenvironment comprises immune cells, cytokines, metabolites, fibroblast, and desmoplastic stroma rich in hyaluronan.

Tumor progression is profoundly influenced by interactions of cancer cells with their environment that ultimately determine whether the primary tumor is eradicated, metastasizes or establishes dormant micro metastases. 

The tumor microenvironment can also shape therapeutic responses and resistance, justifying the recent impetus to target components of the tumor microenvironment, which is best exemplified by the success of immune checkpoint inhibitors in the clinic.