Hematological malignancies in Ukraine in post-Chernobyl era: sources of data and their preliminary analysis.

The major sources of the data on the hematological malignancies in the post-Chernobyl period in the regions of Ukraine differing by the levels of the residual contamination with radionuclides have been analyzed. According to the data collected from the primary hematological facilities in Ukraine in 2010-2017, the incidence of lymphoid neoplasms from mature B cells, acute myeloid leukemia, and multiple myeloma in the most contaminated regions was higher than in the less contaminated ones. For the first time, the relative contribution of the several specific types of leukemia in the total diagnosed hematological malignancies has been analyzed throughout 1997-2017 based on the in-house database compiled by the Reference Laboratory of RE Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, the National Academy of Sciences of Ukraine. In 2011-2017, the Reference Laboratory provided the diagnostic studies in about 26% of all Ukrainian patients with tumors of hematopoietic and lymphoid tissues (34% of patients with different forms of acute and chronic leukemia). The increased proportion of acute myeloid leukemia and chronic lymphocytic leukemia in the total diagnosed cases of overall leukemia in the patients from contaminated regions has been demonstrated following Chernobyl accident.

Myelodysplastic syndromes in Chernobyl clean-up workers.

The studies of the recent decades posed the question of the association between radiation exposure and myelodysplastic syndromes (MDS). This association has been proved in secondary MDS originating upon exposure to chemotherapeutics and/or radiation therapy. The long-term study in Japanese atomic (A)-bomb survivors demonstrated the significant linear dose-response for MDS confirming the link between radiation exposure and this form of hematopoietic malignancies. All these findings provide the strong basis for studying MDS in the persons exposed to radiation following the Chernobyl disaster, especially those in the cohort of Chernobyl clean-up workers of 1986-1987. The data on MDS among Chernobyl clean-up workers (1986-1987) diagnosed in 1996-2012 at the reference laboratory of RE Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology are summarized. MDS cases were diagnosed in 23 persons (21 males and 2 females) having been exposed to radiation as clean-up workers of 1986-1987. Refractory anemia (RA) has been detected in 13, refractory anemia with ring sideroblasts (RARS)-in 2, and refractory anemia with excess blasts (RAEB)-in 8 patients. The median age of those MDS patients was 62.0 years. In addition, 5 cases of chronic myelomonocytic leukemia (CMML) were recorded in the group of Chernobyl clean-up workers with the median time of 14.8 years from 1986-1987 to diagnosis. The association between radiation exposure and MDS is discussed. The suggested life-long risk for myelodysplastic syndromes among A-bomb survivors in Japan highlights the importance of the continuing follow-up studies in the affected populations in the post-Chernobyl period.