Radiation-induced thyroid cancers

Human epithelial thyroid radiation-induced tumorigenesis is the most freque nt radiation-induced tumorigenic process in man. Results of different studi es, concerning the molecular mecanism(s) of epithelial thyroid radiation-as sociated tumorigenesis show: 1) that there is not a significant difference in the frequency of activation of ras, gsp and trk proto-oncogenes between radiation-associated and << spontaneous >> thyroid tumors; 2) the relevant role played by RET/PTC ret proto-oncogene activating rearrangements, in the development of radiation-associated thyroid tumors originated after therap eutic radiation (mainly PTC 1) or the atomic accident of Chernobyl (mainly PTC 3) and 3) suggest that the patients who develop thyroid tumors after a history of irradiation, show a genomic instability consisting in a DNA repa ir defect.