[Induced leukemias and their connection with radiation exposure]

The cytogenetic study of bone marrow cells was performed in 40 patients with secondary leukemias which have arisen after application of cytostatic and/or radiotherapy for primary tumours (Hodgkin's disease, lymphomas, acute lymphoblastic leukemias, breast cancer and other solid tumours). The comparative analysis of results has shown, that the leukemias after irradiating or application of alkylating agents and irradiation, have the quite particular clinico-morphological and cytogenetic characteristics. In 70% of cases these diseases develops as smouldering leukemias with subsequent transformation in M-4, M-6, and rarely M-2 cytochemical variants. Primary cytogenetic events in 60% of researched karyotypes are the losses of long arms or whole chromosomes 5 and 7. In 20% of the researched cases normal karyotype was found, in the left 20%, the changes of a karyotype not including anomalies 5 and 7 chromosomes were detected. The obtained outcomes allow to consider the discharged complex of tags as reference for leukemias, induced by irradiating or chemical agents with similar mechanism of action (alkylating agents, benzene and its derivates). This complex of tags is typical for induced leukemias, and in a combination with definition of a level of stable aberrations in peripheral blood lymphocytes, can be utilised for abjection of radiation-induced leukemias from common mass of cases detected in regions, polluted by radionuclides. In this study in 60% of cases only specific for secondary leukemias chromosomal aberrations, including monosomy 5 and 7, rearrangements of 11q23 were found. On the base of the obtained data the differences in concepts of "secondary" and "induced" leukemias are considered.