THE IMPACT OF NON-TARGETED CELLULAR EFFECTS INDUCED BY LOW EXPOSURES OF IONIZING RADIATION ON LUNG CANCER RISK
Pages 97-100
Lucia-Adina Truta-Popa, Werner Hofmann, Constantin Cosma
Abstract
The objective of this study was to investigate the effect of non-targeted cellular mechanisms on the shape of the lung cancer risk function at low, chronic exposure, relative to the targeted effects induced by alpha particles. The biological endpoint studied in this paper was oncogenic transformation, assumed to be a fundamental step in the induction of carcinogenesis. An initiation-promotion model was proposed for the assessment of lung cancer risk due to the targeted cellular effects. In general, non-targeted effects such as genomic instability and bystander effects amplify the biological effectiveness of a given radiation dose by actually increasing the number of cells affected, in comparison to the number of cells directly irradiated. On the other hand, mechanisms such as induction of apoptosis and adaptive response usually decrease the risk values and thus could be regarded as defense mechanisms against oncogenesis. The non-targeted effects modifying the initial response at the cellular level that will be more thoroughly studied in this paper are genomic instability and induction of apoptosis by surrounding cells.