Introduction.Chronic myelomonocytic leukemia (CMML) is a clonal process caused by transformation at the level of a polypotent hematopoietic stem cell, which is characterized by a set of myelodysplastic/myeloproliferative features. ChMML is diagnosed mainly in elderly (73–75 years) males (1.5–3:1). The incidence of the disease is about 4 cases per 100,000 people. The disease is characterized by slow progression, the risk of developing a blast crisis is 15% within 3-5 years from the moment of diagnosis, under the influence of certain unfavorable factors, the transformation can occur much faster, sometimes lightning fast.

The aim of this research was to to study the peculiarities of the clinical and morphological indicators of peripheral blood and bone marrow of patients with CMML, taking into account the course of the disease depending on the presence in the anamnesis of contact with ionizing radiation.

Materials and methods. A general clinical examination and a morphological study of peripheral blood and bone marrow indicators of patients with CMML suffered after the Chornobyl nuclear power plant (NPP) accident were carried out, in comparison with non-irradiated patients in the dynamics of the course of the disease.

Results . The study of general clinical examination indicators and morphological examination of peripheral blood and bone marrow indicators of patients with CMML suffered after the Chornobyl NPP accident did not reveal any significant difference compared to patients irradiated within the limits of the natural radiation background. Correlation analysis shows a close relationship between the radiation dose and indicators that characterize the anemic syndrome and the dependence of the duration of the disease on clinical features (degree of splenomegaly, number of peripheral blood leukocytes) in patients exposed to ionizing radiation (IR) after the Chornobyl disaster. The duration of CMML in non-irradiated patients was correlated with the number of peripheral blood leukocytes. The results of the cluster analysis confirm the presence of close relationships between the clinical and laboratory parameters of the examined patients with CMML (irradiated, non-irradiated individuals).

Conclusions. For patients from the CMML group who were exposed to IR, the survival rate at the end of the observation period was 46.8%, for non-irradiated patients – 26.2%; a significant difference (p<0.05) in terms of survival was established starting from the 2nd year of follow-up.

Keywords: chronic myelomonocytic leukemia, peripheral blood, bone marrow, ionizing radiation, Chornobyl NPP accident.