ACUTE MYELOID LEUKEMIA, PROSTATE AND SKIN CANCER IN ACUTE RADIATION SYNDROME SURVIVOR AFTER THE 1986 CHERNOBYL NUCLEAR ACCIDENT: CASE REPORT

Prognostic impact of chromosomal changes at relapse after allogeneic hematopoietic cell transplantation for acute myeloid leukemia or myelodysplastic syndrome

Chromosome analysis is a powerful prognostic tool in myeloid malignancies. Recipients who experience relapse after allogeneic hematopoietic cell transplantation (allo-HCT) often show chromosomal changes between diagnosis and relapse. However, the clinical impact of chromosomal changes and the efficacy of post-relapse treatment according to chromosomal changes have not been fully investigated. We retrospectively analyzed 72 recipients who had experienced relapse after allo-HCT for acute myeloid leukemia or myelodysplastic syndrome. We categorized them into two groups: with or without clonal chromosomal changes at relapse after allo-HCT. Post-relapse survival was shorter in the clonal chromosomal change group (median 117 days vs 275 days, P = 0.019). Moreover, acquisition of chromosome 7 abnormality or complex changes tended to be associated with inferior survival in a univariate analysis (median 92 days vs median 173 days, P = 0.043), and this adverse impact was confirmed in a multivariate analysis (hazard ratio 2.07, P = 0.024). The patterns of chromosomal changes from diagnosis to relapse after allo-HCT were heterogenous, and further investigations are required to clarify the effect of individual chromosomal changes.

Pattern of chromosomal aberrations persisting over 30 years in a Chernobyl Nuclear Power Plant accident survivor: study using mFISH

The long-term in vivo cytogenetic effects of high-dose radiation exposure can be traced in accidentally irradiated persons, and particularly useful for developing strategies of monitoring and therapy of such patients, as well as for elucidating the fundamental aspects of hematopoiesis and radiobiology. Using 24-color fluorescent in situ hybridization (mFISH), we analysed the frequency and the spectrum of chromosomal aberrations (CA) in peripheral blood lymphocytes of the Chernobyl Nuclear Power Plant (NPP) accident victim 30, 31, 32 and 33 years after acute accidental exposure to high-dose gamma radiation of the whole body. Totally, 993 metaphase cells were analyzed (or 219, 272, 258, 244 cells each year), of which 297 were aberrant. Our study demonstrated a constant aberrant cell frequency at 28% in 2016-2018 years, while in 2019, a significant increase up to 35% occurred due to contribution of significantly elevated frequency of simple aberrations in the absence of evident recent genotoxic factors. Four clonal aberrations were detected, three of which persisted for more than one year at a frequency up to 2.5% of analyzed cells. The distribution of 731 breakpoints per individual chromosomes was nearly proportional to their physical length, excepting Chromosomes 13 and 20, which were significantly breakpoint-deficient compared to the genome median rate. Monitoring of the long-term effects on chromosomal instability caused by radiation exposure is important for understanding and predicting the long-term effects of ionizing radiation.

Autologous Hematopoietic Recovery after Unrelated Umbilical Cord Blood Transplantation with Myeloablative Conditioning for Acute Myelogenous Leukemia

Autologous hematopoietic recovery after allogeneic hematopoietic cell transplantation (allo-HCT) is rare in patients who receive myeloablative conditioning (MAC). Autologous hematopoietic recovery suggests graft rejection, leading to concerns about subsequent disease relapse. We herein report a rare case of a patient with acute leukemia who experienced autologous hematopoietic recovery after cord blood transplantation (CBT) with total body irradiation-based MAC. Chromosomal abnormalities were repeatedly detected without any disease relapse for eight months. The accumulation of similar cases is required to accurately assess the incidence and clinical outcomes of autologous hematopoietic recovery after CBT with MAC.