腫瘍の微小循環系とくにhypoxiaと放射線・温熱感受性

概要

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Oxygen deficient hypoxic cells, which are resistant to sparsely ionizing radiation, have been identified in most animal and some human solid tumors. This hypoxia (H. ) can be divided into 2type of hypoxia. namely chronic H. arising from an oxygen diffusion limitation and acute H., resulting from transient stoppages in microgional blood flow. Although clinical trial have attempted to overcome these defferencies, results have been far from satisfactory. Recent studies have shown that nicotinamide could improve tumor blood perfusion in tumors. In many solidtumors, the pH of the extracellular fluid is acidic, low oxygen tension and decreased blood flow. During hyperthermia at the temperature usually applied clinically (above 43°C), the heat induced reduction in blood flow is often greater intumor than in normal tissues and then. their temperature rises higher. However, recent studies revealed that modest temperature hyperthermia (MTH) may be an efficient and useful means to improve the oxygenation of human tumors. Recent studies showed that hypoxia induces apoptosis in transformed cells and that further genetic alterations, such as p53 mutation and bcl-2 overexpression, substantially suppress apoptosis induced by radiation and chemotherapy. These results explain the resistance of tumors to cancer therapy.
Kinki Brain Tumor Pathology Conferenceの論文