Hematological malignancies in Chernobyl clean-up workers (1996-2010)

Abstract

Background: Even in 25 years after Chernobyl catastrophe, the interpretation of the findings on leukemia risk among Chernobyl clean-up workers is still a point of much controversy. Precise diagnosis of the main types of hematopoietic malignancies according to FAB classification and new WHO classification and comparison of these data with that in the general population will be helpful in estimating the relative contribution of the radiation factor to the overall incidence of such pathologies.

Methods: The data on 295 consecutive cases of malignant tumors of hematopoietic and lymphoid tissues in Chernobyl clean-up workers diagnosed in 1996-2010 are given in comparison with the data of 2697 consecutive patients of general population of the same age group. The complex of diagnostic techniques was used including morphology and cytochemistry of bone marrow and peripheral blood cells as well as immunocytochemical techniques (APAAP, LSAB-AP) and the broad panel of monoclonal antibodies to lineage specific and differentiation antigens of leukocytes.

Results: All the main forms of tumors of hematopoietic and lymphoid tissues were diagnosed among clean-up workers under study in 10-25 years after Chernobyl catastrophe including myelodysplastic syndromes (MDS), acute leukemias (ALL and AML), chronic myelogenous leukemia (CML) and other chronic myeloproliferative neoplasms, chronic lymphocytic leukemia (B-CLL) and other chronic lymphoproliferative diseases of B and T cell origin. Among clean-up workers with hematopoietic malignancies, MDS percentage tended to exceed that in the group of patients representing the general population examined at the same period (5.42% vs. 3.70%). Among 46 AML cases in clean-up workers, leukemia was preceded by MDS in seven patients. Also CML percentage was higher in group of patients representing clean-up workers (9.01% vs. 6.59%). B-CLL was a predominant form of hematopoietic malignancies in clean-up workers under study (26.10%). Nevertheless, B-CLL percentage in patients of clean-up workers group did not differ significantly from that in the patients of general population. The multiple myeloma percentage in the group of patients belonging to clean-up workers in our study was higher than in the patients of general population (6.44% vs. 4.0%).

Conclusions: The verified diagnosis of tumors of hematopoietic and lymphoid tissues according to the up-to-date classifications (EGIL, WHO) could be the prerequisite for further molecular genetic and analytical epidemiology study of leukemias that may be related to Chernobyl catastrophe.

Keywords: Chernobyl clean-up workers, leukemias, cytochemistry, immunophenotyping