Effect of interferon-α on chromosome abnormalities in treated chronic myelogenous leukemia patients

To investigate the relationship of chromosomal aberrations at blastic crisis (BC) in chronic myelogenous leukemia (CML), with previous therapies and with atomic bomb (AB) exposure, we studied 114 CML patients who developed BC, including 23 AB survivors in Hiroshima. In total, only 45.6% showed major-route abnormalities, which figure was far lower than those previously reported, implying possibility of geographical difference. Occurrence of major-route abnormality was not associated with either duration of chronic phase or survival time after BC. Patients treated with interferon-α (IFNα) showed lower frequency of major-route abnormalities and lower number of abnormal chromosomes than did patients treated with busulfan (Bu). The frequency of trisomy 8 was lower and monosomy 7 was higher in IFNα-treated than in Bu-treated patients. The frequency of unusual abnormalities at BC in IFNα-treated patients was indistinguishable from those in Bu-treated patients and, notably, a more common (40%) feature in IFNα-treated patients was no change in the cytogenetic picture. Thus, we conclude that IFNα action on chromosome aberration is basically quite neutral and that IFNα does not induce any specific aberrations, including unusual ones at BC, with an exception of deletion of chromosome 7. Atomic bomb exposure status did not make any difference in secondary abnormalities at BC.