Radiobiologic modeling of cytoprotection effects in radiotherapy.
OBJECTIVE
To investigate the potential for mathematical modeling of the normal tissue-sparing effects of cytoprotective agents used in conjunction with radiotherapy and chemotherapy.


METHODS
The linear quadratic model was modified to include a "cytoprotection factor," in two alternative ways. The published results on the incidence of treatment-related oral mucositis in patients treated for head-and-neck carcinoma using radiotherapy alone or combined with chemotherapy were assessed against the model to determine the likely values of the cytoprotection factor required to confer a reasonable degree of cytoprotection.


RESULTS
In both of the model alternatives considered, a cytoprotection factor value of < or = 0.85 was required for a clinically detectable degree of cytoprotection to be realized. A cytoprotection factor value of 0.85 would mean that the radiation sensitivity coefficients would be effectively reduced by 15% on account of the action of the cytoprotector.


CONCLUSIONS
The incorporation of a cytoprotection factor into an existing linear quadratic method would allow a quantitative assessment of cytoprotection and could be useful in the design of future clinical studies.
Plataniotis
George A
GA
Department of Radiotherapy, University Hospital of Larissa, Larissa, Greece. gplatan@med.uth.gr
Dale
Roger G
RG
D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*; D006801:Humans; D016014:Linear Models; D008954:Models, Biological; D011832:Radiation Injuries / Q000517:prevention & control*; D011836:Radiation Tolerance; D011837:Radiation-Protective Agents / Q000627:therapeutic use*; D012062:Relative Biological Effectiveness; D013280:Stomatitis / Q000517:prevention & control*
D011837:Radiation-Protective Agents