Introduction: Tumor as an Organ

In this issue of Seminars in Radiation Oncology, we focus on the theme of tumors as dysfunctional organs. Hanahan and Weinberg have pointed out in their most recent “Hallmarks of Cancer” review that tumors contain communities of cells and stromal elements that work in concert to promote tumor cell growth, angiogenesis, invasion, and metastasis as well as immune system evasion. The features of this microenvironment also influence the efficacy of therapy. As such, an understanding of the tumor microenvironment is highly relevant to the development of new therapeutic targets. The cover of this special issue highlights the cellular complexity of the microenvironment of the neural stem cell niche. This normal tissue contains a mixture of stem cells and other supporting cells. Interactions of stem cells with the microenvironment in tumors is altered. In tumors, these cellular components exist in a state of hypoxia, lactic acidosis, nutrient deprivation, and elevated oxidative stress. These stresses stimulate intercellular communication during tumor growth and are modified in response to therapy to facilitate treatment resistance and promote tumor aggressiveness. Although the microenvironment is only beginning to be understood, important discoveries about its unique nature have led to innovative methods that hold promise to broaden the therapeutic margin because such conditions do not exist in normal tissues.
Source: Seminars in Radiation Oncology - Category: Cancer & Oncology Authors: Source Type: research