PROGNOSIS OF THE COURSE OF CHORNOBYL-ORIGINATED ACUTE LYMPHOBLASTIC LEUKEMIA IN CHILDREN IN UKRAINE DEPENDING ON THE REASON OF STANDARD CHEMOTHERAPY INTERRUPTION.

Abstract

Estimation of the bone marrow haemopoietic status depending on the reasons and duration of breaks in a standard chemotherapy (BFM-ALL protocol) to predict the course of acute lymphoblastic leukemia (ALL) in chil- dren exposed to low doses of ionizing radiation after the Chornobyl accident. The ALL patients (n = 34) were examined within 5 stages of a program chemotherapy. The clinical symptoms, hemogram and myelogram data were analyzed. The radiation dose on bone marrow, initial leuko- cyte count, variants and prognosis of ALL course were accounted. Days of the stopped chemotherapy, type and fre- quency of complications (septic processes, febrile neutropenia, toxic hepatitis, granulocytopenia degree), and the prognosis of disease course (child living status, i.e. alive or died) were estimated. There were abnormal differentiation processes and high percentage of lymphoblasts (86.2 ± 3.3) % in bone marrow in the 1st acute period. Hematological remission was established in all patients on the 33rd day of chemothe- rapy. In a half of cases the haematopoietic recovery occurred by a granulocyte-monocyte type. One third of patients presenting an erythroid type of haemopoiesis died later. The inverse correlation was found between the number of myelocaryocytes and disease prognosis (rs = -0.49). Breaks in chemotherapy for various reasons were recorded. The number of patients with granulocytopenia was greater at the phase 1 and 2 of protocol I and protocol M application, coinciding with a higher incidence of complications. An inverse correlations between the prediction of ALL course and sum of days of breaks between the protocol M and phase 1 of protocol II (rs = -0.56), as well as the duration of the phase 2 of protocol II (rs = -0.62) were found. The radiation dose on bone marrow was (5.37 ± 1.23) mSv. No relationship was found between the radiation doses, ALL variants and disease course. Prognosis of ALL course in children depends on the type of haemopoietic recovery and reasons of breaks in a standard chemotherapy. Interaction between the haemopoiesis functioning and microenvironment and that of their regulation are the key mechanisms of above-mentioned abnormalities, which is the basis for further research.