Microenvironment-a role in tumour progression and prognosis.

In addition to malignant cells, solid tumours comprise supporting stromal tissue that consists of Extra Cellular Matrix (ECM), connective tissue cells, inflammatory cells and blood vessels. The stromal compartment and the malignant cells together shape the tumour microenvironment that in turn determines tumour progression and efficacy of anti-tumour treatments. It is now recognized that the host microenvironment undergoes extensive change during the evolution and progression of cancer. This involves the generation of Tumour-Associated Fibroblasts (TAFs), which, through release of growth factors and cytokines, lead to enhanced angiogenesis, increased tumour growth and invasion. It has also been demonstrated that TAFs may modulate the Cancer Stem Cell (CSC) phenotype, which has therapeutic implications. Understanding the various components in the tumour microenvironment may afford us the opportunity to develop new drugs that target these reversible nonmutational events in the prevention and treatment of cancer.