Radiation carcinogenesis in mouse skin and its threshold-like response

Experiments on the dose-response of tumor development induced by repeated local beta irradiation of the back of mice are summarized. Results indicated a 100% tumor incidence on irradiation at 2.5-11.8 Gy per exposure (dose-saturation effect) and the threshold-like dose response at lower doses. The mechanism underlying these phenomena is discussed on the basis of the tissue-misrepair model, that is misrepair caused by repeated stimulation of cell growth after repeated tissue injury.