Quantitative evaluation of tumor radioresistance and analysis of its causes

A method of quantitative analysis of solid tumor radioresistance was described using the relationship between tumor control dose and tumor volume. Both theoretical considerations and experimental data indicated that causes of radioresistance such as the number of target cells per unit volume and radiosensitivity of most radioresistant target cells could be analyzed by this method. Analysis of our own data concerning cervical lymph node-metastases and other types of tumors reported in the literature showed that the radioresistance sharply increased from a certain volume not only because of increase number of target cells, but also because of increased radioresistance of target cells. (author)