Abstract
BACKGROUND: A mathematical model of the radiation-induced cancer was devised to explain the change of incidence rates pursued by Radiation Effect Research Foundation for 25 years. AIM: The aim of this work is construction of mechanisms of radiation-induced cancer and cancers observed in the daily life. METHODS AND RESULTS: First, we found a way to separate spontaneous cancers from radiation-induced cancers observed among atomic-bomb victims in Hiroshima and Nagasaki districts by using a constructed algorithm. The isolated incidence rates of radiation-induced cancers were reproduced by a two-stage model mechanical collision of impinging radiation with cells and succeeding mutation of the damaged cell to cancer. This model satisfactorily reproduced observed solid cancer incidence rates. We further attempted to construct a mathematical model for the age-dependence of spontaneous cancers appearing in the daily life and concluded that the cancer should be generated at cell division. CONCLUSION: With these findings, we reached to a conclusion that cancers may be suppressed by eliminating damaged cells with mild-dose radiation.