On the importance of prompt oxygen changes for hypofractionated radiation treatments.
This discussion is motivated by observations of prompt oxygen changes occurring prior to a significant number of cancer cells dying (permanently stopping their metabolic activity) from therapeutic agents like large doses of ionizing radiation. Such changes must be from changes in the vasculature that supplies the tissue or from the metabolic changes in the tissue itself. An adapted linear-quadratic treatment is used to estimate the cell survival variation magnitudes from repair and reoxygenation from a two-fraction treatment in which the second fraction would happen prior to significant cell death from the first fraction, in the large fraction limit. It is clear the effects of oxygen changes are likely to be the most significant factor for hypofractionation because of large radiation doses. It is a larger effect than repair. Optimal dose timing should be determined by the peak oxygen timing. A call is made to prioritize near real time measurements of oxygen dynamics in tumors undergoing hypofractionated treatments in order to make these treatments adaptable and patient-specific.
Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705 USA. Department of Human Oncology, University of Wisconsin-Madison, Madison, WI 53703 USA.
Michael
M
Kissick
David
D
Campos
Albert
A
van der Kogel
Randall
R
Kimple
D002470:Cell Survival / Q000528:radiation effects; D019583:Dose Fractionation, Radiation; D008954:Models, Biological; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy; D010100:Oxygen / Q000378:metabolism*; D035501:Uncertainty
D010100:Oxygen