Comparison of Hprt variant frequencies and chromosome aberration frequencies in lymphocytes from radiotherapy and chemotherapy patients: A Prospective Study
- 1 January 1991
- journal article
- Published by Wiley in Environmental and Molecular Mutagenesis
- Vol. 18 (2) , 126-135
- https://doi.org/10.1002/em.2850180208
Abstract
The autoradiographic 6‐thioguanine‐resistant mutant lymphocyte assay and a chromosome aberration assay were used to determine the time‐course of appearance and persistence of elevated frequencies of hprt variants and dicentric chromosomes in patients receiving x‐irradiation therapy. Twelve cancer patients, treated with 180–200 cGy/day, 5 days/wk, for 3–7 wk, were studied before treatment, at various weekly intervals during treatment, and after treatment. The hprt mutation assays were done with frozen/thawed lymphocytes isolated from aliquots of the same blood samples used for the chromosome aberration assays. The hprt variant frequencies (Vfs) of only 4 of the 7 patients assayed at 2 wk of treatment were elevated over pre‐treatment Vfs, but during the 3rd and 4th weeks of treatment there were significant (P < 0.01) 5‐ to 15‐fold increases in all Vfs. By 6–32 wk after treatment Vfs had fallen to levels only slightly higher than the mean pre‐treatment Vf. The frequencies of cells with dicentric chromosomes were significantly increased (P < 0.01) after 1 wk of radiotherapy, continued to increase during therapy, and remained elevated after treatment. Five multiple sclerosis patients were also studied before and at 2 and 4 wk intervals after treatment with monthly i.v. doses of 750 mg/m2 of cyclophosphamide (CP). There were no significant elevations in chromosome aberrations at these post‐treatment sample times. Previous assays for hprt mutants, done with aliquats of the same blood samples (Ammenheuser et al.: Mutat Res 204:509–520, 1988), had shown 8‐ to 20‐fold increases in Vfs 2 wk after the 1st CP treatment. Our results demonstrate the complementary nature of these two human monitoring assays and emphasize the importance of careful selection of optimal sampling times.Keywords
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