Chromosome aberrations after radiotherapy in patients treated for non Hodgkin's lymphoma.

Chromosome aberrations were evaluated in the lymphocytes of 30 patients who had undergone radiotherapy several years before for non-Hodgkin's lymphoma. Twelve had received 20 Gy over the entire abdomen (group I), 12 wholebody irradiation at 1.5 Gy (group II) and 6 wholebody irradiation at 15 Gy (group III). Unirradiated patients seen for cytogenetic analysis during the same period served as controls. Overall results for the irradiated population were 13/27 (48%) evaluable patients with chromosome aberrations and 50/710 (7%) abnormal cells for a total of 73 aberrations (unstable: 35, stable: 38). The frequency of aberrations was statistically higher in group I (12% of cells) than in groups II (3.5%, p < 0.0001) and III (2.5%, p < 0.0002). Differences in irradiation dose and volume may account for the variations between groups.