Metastasis and the Tumor Microenvironment

The tumor microenvironment (TME), consisting of the extracellular matrix (ECM) and cells surrounding tumor cells, exhibits dramatic abnormalities over the microenvironment of normal tissues. These abnormalities, characterized by a state of chronic infl ammation, support the growth and metastasis of tumor cells (Figure 5.1). Thus, it is advantageous for cancer researchers to consider cancer cells in the context of their surrounding environment rather than the isolation of a cell culture dish. This context is important for understanding how neoplastic lesions develop, proliferate, metastasize, and evade the immune system. Additionally, understanding the TME can inform the development of new anticancer drugs, particularly in the fi eld of tumor immunology. A number of drugs are currently on the market or under evaluation that reverse or seek to overcome abnormalities of the TME. Furthermore, for any new drug under development, its access to, stability in, and impact on the TME should all be considered.