Effects of X-irradiation on the cell population kinetics in a model tumour and normal tissue system: implications for the treatment of human malignancies

Abstract

Using standard autoradiographic techniques following single or repeated injections of tritiated thymidine, the cell cycle time of the cells of the normal epithelium of the hamster cheek pouch and of chemically induced squamous carcinomata in the pouch has been measured by a variety of methods. The median cell cycle time of the proliferating tumour cells was found to be 11 hours, whereas that of the normal epithelial cells was 130–140 hours. Following acute doses of either 500 or 1,000 rads, the generation cycle of the malignant cells was found to be slightly elongated. On the other hand, the normal basal cells of the epithelium suffered a 20–30 per cent shortening of their cell cycle after these doses. The relevance of these data to the clinical situation is considered.