title: Tissue misrepair hypothesis for radiation carcinogenesis.
abstract: Dose-response curves for chronic leukemia in A-bomb survivors and liver tumors in patients given Thorotrast (colloidal thorium dioxide) show large threshold effects. The existence of these threshold effects can be explained by the following hypothesis. A high dose of radiation causes a persistent wound in a cell-renewable tissue. Disorder of the injured cell society partly frees the component cells from territorial restraints on their proliferation, enabling them to continue development of their cellular functions toward advanced autonomy. This progression might be achieved by continued epigenetic and genetic changes as a result of occasional errors in the otherwise concerted healing action of various endogenous factors recruited for tissue repair. Carcinogenesis is not simply a single-cell problem but a cell-society problem. Therefore, it is not warranted to estimate risk at low doses by linear extrapolation from cancer data at high doses without knowledge of the mechanism of radiation carcinogenesis.
authors.affiliation: Atomic Energy Research Institute, Kinki University, Osaka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kondo
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000009:adverse effects; D004260:DNA Repair / Q000235:genetics*; D006801:Humans; D009381:Neoplasms, Radiation-Induced / Q000209:etiology / Q000235:genetics*; D009689:Nuclear Warfare; D013911:Thorium Dioxide / Q000009:adverse effects
chemical_list: D003287:Contrast Media; D013911:Thorium Dioxide