DNA-REPAIR, CELL-KILLING AND NORMAL TISSUE-DAMAGE

Background: Side effects of radiotherapy in normal tissue is determine d by a variety of factors of which cellular and genetic contributions are described here. Material and Methods: Review. Results: Normal tiss ue damage after irradiation is largely due to loss of cellular prolife rative capacity. This can be due to mitotic cell death, apoptosis, or terminal differentiation. Dead or differentiated cells release cytokin es which additionally modulate the tissue response. DNA damage, in par ticular non-reparable or misrepaired double-strand breaks are consider ed the basic lesion leading to G1-arrest and ultimately to cell. inact ivation. Conclusion: Evidence for genetic bases of normal tissue respo nse, cell killing and DNA-repair capacity is presented. However, a dir ect link of all 3 endpoints has not yet been proved directly.