Biological and Clinical Approach to the Problem of Tumor Radiosensitization

The aim of every form of radiotherapy has always been the selective elimination of tumor cells from the cancerous body. Unfortunately over 70 years’ experience has shown that this goal is not usually feasible even at the local site. In attempting to explain the «failure» of traditional radiotherapy account must be taken of recent discoveries in cellular radiobiology, especially: a) the roughly equal «intrinsic radiosensitivity» of the various mammalian cells, whether normal or neoplastic; b) the relative radioprotection enjoyed by some normal and cancer cells in the cancerous organism. The two main problems facing radiotherapy at present are: 1) how to interfere with the cell's intrinsic radiosensitivity from the outside by physical, chemical and biological means; 2) how to interfere selectively with neoplastic cells. It is thus clear that modern radiotherapy calls for appropriate preparation of the substrate: the cancerous organism. The recent successful application of chemical substances tried in other fields of human pathology to attempts at radiosensitizing tumors is a promising approach to this research of new paths with old tools.