Advances in cellular and molecular radiation oncology

Radiation therapy remains a mainstay for the treatment of urologic malignancies, offering the opportunity for organ preservation as the primary treatment and serving in combination with surgery and systemic therapy for the more advanced tumors. Using prostate cancer as a model, classic radiation biology will be linked to the newer aspects of cellular and molecular biology of radiation oncology. Knowledge of classic radiation biology has provided new therapeutic approaches in dose fractionation, radiation sensitization, and normal tissue protection. Radiobiologic parameters derived from measuring radiation survival curves, tumor cell kinetics, and tumor oxygenation may provide the means to predict response to treatment. The basic mechanisms behind tumor and radiation biology that are under investigation include DNA recombination and repair, signal transduction, gene regulation, apoptosis, the cellular stress response, and the effect of the tumor microenvironment. The knowledge derived from improved understanding of the new biologic concepts, coupled with the superior technical capabilities now available for treatment delivery, is producing novel approaches in the clinic that may improve both the quality and quantity of life for the urologic cancer patient.