Patterns of hematological malignancies in patients from regions of ukraine with different levels of contamination following the chornobyl nuclear disaster

Abstract

Introduction: Chornobyl catastrophe on April 26, 1986 resulted in the release of large amounts of radioactive materials causing the heavy contamination of the vast regions of Ukraine, Republic of Belarus, and Russian Federation as well as trace contamination throughout European countries. The relation between the protracted exposure of the population of Ukraine to the ionizing radiation since 1986 and the incidence of the tumors of hematopoietic and lymphoid tissues has not been yet elucidated. The patterns of the distribution of the various forms of hematological malignancies diagnosed in the regions of Ukraine contaminated with radionuclides have not yet been studied. Therefore, the aim of our study was to analyze the relative contribution of several specific forms of leukemia in the total hematopoietic malignancies diagnosed in the Ukrainian Reference Laboratory (URL) in 1997–2017. Methods: The URL provides the diagnostic studies covering about one third of the cases of the tumors of hematopoietic and lymphoid tissues in Ukraine. The up-to-date techniques of cytomorphological, cytochemical and immunophenotypical analysis in accordance to the recent WHO 2017 and ICD-11 classifications are used for diagnostic studies. The diagnostic findings of the URL were compiled in the database (about 30 thousand cases in total) with the reference to the place of residence of the patients. Results: The analysis of the proportions of each specific form of hematopoietic malignancies diagnosed by the URL over 20-year period demonstrated the increased relative contribution of AML (26.0% vs. 22.5%) and CLL (30.6% vs. 27.4%) in the total diagnosed cases of overall leukemia in the patients from contaminated areas as compared to non-contaminated ones. Nevertheless, no trends in redistribution of MDS proportion among the patients of the regions contaminated with radionuclides have been evident. Conclusions: The study provided for 20 years allowed us to follow several differences in the distribution of some specific forms of the hematological malignancies among the patients from contaminated areas. The increased proportion of CLL deserves further analysis taking into account some recent data suggesting the association between long-term exposure to the low doses of ionizing radiation.