Progress in radiation biology and cancer researches

This chapter is organized into six sections. The first section deals with 'biology in radiation oncology', introducing the current researches concerning time, dose and fractionation factors, the effect of high LET radiation, and hypoxic cell sensitizers. Section II gives an outline of 'pathology in radiotherapy'. 'Radiotherapy for cancer and immunity', given in section III, points out the involvement of various immunologic factors of individual hosts in radiotherapy. In section IV, ''repair of radiation effects'' is discussed in the light of hypoxic cell sensitizers, PLD repair inhibitors, and hyperthermia. Section V covers 'combination of radiotherapy and chemotherapy', discussing synergism of their combined effect on a biological basis at tissue and cell levels. In the last section, 'basis of fractionated irradiation', the basic principle of fractionated irradiation ranging from the Ellis' nominal standard dose concept to the linear quadratic (LQ) model is reviewed. The LQ theory-based hyperfractionation and hypofractionation, which have been elaborated in the literature, are tabulated. (Namekawa, K.)