Radiation-induced carcinogenesis. Lecture 26. Initiation, promotion, progression Dose response for radiation-induced cancers Importance of age at exposure and time since exposure Malignancies in pre-natally exposed children Second tumors in radiation therapy patients
Initiating events in chromosomes (such as aberrations) or in DNA. Initiators are radiation, chemical carcinogens, UV etc
Low doses of tumor initiators are necessary to convert the initiated cells to cancer cells. Examples are TPA, phorbol esters, estrogen and excessive fat.
Increased genetic instability resulting in aggressive growth phenotype
Evidence comes from:
and time since exposure
Children and young adults are much more susceptible to
radiation-induced cancer than the middle- and old-aged.
Squamous cell and basal cell carcinoma have been most frequently observed
number of specific cancer sites
For the population
composed of both
sexes the ICRP