Epigenetic nature of radiation carcinogenesis at low doses.

The present paradigm of radiation-induced carcinogenesis has been based on somatic mutation theory initiating a mutation in somatic cells derived from DNA damage by ionizing radiation. A non-threshold linear model has been assumed from high doses to low doses. As an alternative to this, we are proposing a new model that epigenetic changes induced by low dose irradiation may be a first step of carcinogenesis. Our preliminary data suggesting the epigenetic nature and reports on various stress response to ionizing radiation are presented.