Time-Dose Relationships for Human Tumors: Estimation from Nonrandomized Studies
Tumor cells proliferate before, during, and, unfortunately, in some cases after radiotherapy. With our current radiobiological knowledge, we would expect this fact to result in a reduced probability of local tumor control if the same dose-fractionation schedule were to be applied in a longer overall time. However, independent of any mechanistic considerations at the cellular level, it is a problem for clinical science to decide to what extent an alteration of the treatment time alters the tumor control probability. At first sight this should be a simple task, but a multiple of methodological problems hamper the interpretation of the clinical studies published so far, and the magnitude of the time factor remains controversial at the time of writing. The aim of this chapter is to identify a number of these problems and to review critically our current knowledge of the time factor for human tumors.
KeywordsTreatment Time Local Control Local Control Rate Biological Effective Dose Tumor Control Prob
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