[The tumoral microenvironment: feeding resources, battle field and therapeutic target in cancer]

Tumors grow surrounded by a complex cellular and tissular microenvironment. Its components influence disease outcome, some accelarating growth and invasion and others blocking it. From the very first steps leading a normal tissue to dysplasia, followed by a benign tumor which may become locally invasive and metastatic, interactions between the transformed cells and their microenvironment direct the evolution of this process. Chronic inflammation in a tissue favors tumor first appearance which then accentuate the nutritional and energetic properties of their microenvironment by producing neoangiogenic, immunosuppressive and inflammatory molecules. In contrast a strong memory Th1/cytotoxic reaction can prevent the transition from benign to malignant tumors and control cancer invasivness and metastasis. Knowledge of these multiple phenomena, discussed in the different articles of the present issue has a major clinical impact, since new prognostic tests and efficient novel therapeutic approaches which target the tumor microenvironment are actively developed.