Human in vivo radiation-induced biomarkers: gene expression changes in radiotherapy patients.

After initially identifying potential biomarkers of radiation exposure through microarray studies of ex vivo irradiated human peripheral white blood cells, we have now measured the in vivo responses of several of these biomarker genes in patients undergoing total body irradiation. Microarray analysis has identified additional in vivo radiation-responsive genes, although the general in vivo patterns of stress-gene induction appear similar to those obtained from ex vivo white blood cell experiments. Additional studies may reveal correlations between responses and either diagnosis or prognosis, and such in vivo validation marks an important step in the development of potentially informative radiation exposure biomarkers.