DNA-BASE DAMAGE IN LYMPHOCYTES OF CANCER-PATIENTS UNDERGOING RADIATION-THERAPY

We investigated DNA base damage in genomic DNA of lymphocytes of cance r patients undergoing radiation therapy, Lymphocyte chromatin samples were analyzed by gas chromatography/isotope-dilution mass spectrometry for DNA base damage. The results provided evidence for formation of t ypical hydroxyl radical-induced base modifications in genomic DNA of l ymphocytes. Different levels of DNA products in individuals were obser ved and, in the case of some patients, there was no significant produc t formation, possibly resulting from differences between individuals a nd between the types of radiation exposures. Decreases in product leve ls after an initial increase by radiation exposure were observed. This may indicate the removal of modified bases from lymphocyte DNA by cel lular repair.