The importance of genetics for the optimization of radiation therapy. A hypothesis.

There is growing evidence that a fraction of cancer patients, perhaps as high as 15%, is radiation sensitive because of the action of specific genes. It seems likely that in the near future we shall be able to identify these patients by DNA probes. Therefore, we have calculated the impact on radiation therapy of removing these patients and treating the rest more aggressively. In particular, we assumed that the radiation oncologist will treat with an effective therapeutic dose corresponding to a 5% risk of serious normal tissue injury. Our results, in several instances, show a considerable increase in local control when the 5, 10, or 15% of the most radiosensitive patients are removed from the treated group. This is so, even if we assume that the tumor cells, as well as the normal cells, in radiosensitive patients are more radiosensitive than the tumor cells in patients of normal radiosensitivity.