Biologic basis for radiation oncology.

Improved understanding of the underlying biologic mechanisms that pertain to radiation oncology is providing an explanation for the cellular and tissue responses to ionizing radiation and is leading to the potential for novel therapeutic strategies. Among the areas of intensive investigation are: DNA recombination and repair, signal transduction, gene regulation, apoptosis, the cellular stress response, and the effect of the tumor microenvironment. These new biologic concepts, coupled with the superior technical capabilities now available for treatment delivery, are paving the way for new clinical approaches to improving both the quality and quantity of life for the cancer patient.