Effects ot therapeutic doses of ionizing radiation on peripheral lymphocyte chromosomes in cancer patients

A cytogenetic study was conducted on a group of 17 female 39 to 70-year-old patients receiving therapeutic doses of local ionizing fractionated radiation for uterine collum carcinoma. Radiotherapy was carried out by intracavitary exposure of reproductive organs to 137Cs or external exposure to bremsstrahlung from a 48 MV Betatron unit and to a 60Co Gammatron unit. Lymphocyte cultivation time was 48 hours. Structural chromosome aberrations were scored in the course of treatment after local application of 2000, 3000, 5000, and 6000 rad focal doses. Aberrant cell yields showed linear dependence on dose, while exchange aberrations and aberration percentages displayed a quadratic dose-response. The amount of chromosome damage incurred was significantly larger in patients treated with percutaneous radiotherapy as compared with those receiving intracavitary treatment. At the 6000-rad dose level, chromsome aberrations per cell were found to diminish. (author)