THE ALKALINE SINGLE-CELL GEL-ELECTROPHORESIS (SCGE) ASSAY APPLIED TO THE ANALYSIS OF RADIATION-INDUCED DNA-DAMAGE IN THYROID-CANCER PATIENTS TREATED WITH I-131

The alkaline single-cell gel electrophoresis (SCGE or Comet) assay app ears to be a promising tool for measuring DNA damage at the individual cell level in both in vitro and in vivo studies. To provide further d ata on the possible applicability of this assay in human biomonitoring studies, we have evaluated the eventual genetic damage induced by the rapeutic exposure to I-131, by measuring the Comet length and the amou nt of DNA damage in peripheral blood leukocytes from a group of 28 thy roid cancer patients who received I-131 sodium iodide via oral adminis tration. Blood samples were taken just before the treatment and 1 week after it. From the results obtained after radioiodine therapy, a smal l increase in the Comet length and in the grade of DNA damage is obser ved; however, this increase is not statistically significant because o f inter-individual variability and the variable responses before and a fter I-131 treatment. Considering our previous studies showing signifi cant increases in the frequency of cytogenetic damage (when measured a s micronuclei) in patients treated with relatively low doses of I-131, the results obtained in the present work by using the Comet assay cou ld indicate that 1 week after the exposure most of the radioiodine-ind uced DNA lesions, that can be detected with this assay, have already b een repaired. (C) 1998 Elsevier Science B,V.