Clinical characteristics of chronic lymphocytic leukemia occurring in chornobyl cleanup workers

Abstract

The recently demonstrated radiation-induction of chronic lymphocytic leukemia (CLL) raises the question as to whether the amount of radiation exposure influences any of the clinical characteristics of the disease. We evaluated the relationship between bone marrow radiation doses and clinical characteristics and survival of 79 CLL cases diagnosed during 1986–2006 in a cohort of 110,645 male workers who participated in the cleanup work of the Chornobyl nuclear accident in Ukraine in 1986. All diagnoses were confirmed by an independent International Hematology Panel. Patients were followed up to the date of death or end of follow-up on October 31, 2010. The median age at diagnosis was 57 years. Median bone marrow dose was 22.6 milligray (mGy) and was not associated with time between exposure and clinical diagnosis of CLL (latent period), age, peripheral blood lymphocyte count or clinical stage of disease in univariate and multivariate analyses. A significant increase in the risk of death with increasing radiation dose was observed (P=0.03, hazard ratio=2.38, 95% confidence interval: 1.11,5.08 comparing those with doses ≥22 mGy to doses <22 mGy). After adjustment for radiation dose, survival of CLL cases was significantly shorter among those with younger age at first exposure, higher peripheral blood lymphocyte count, more advanced clinical stage of disease and older age at diagnosis (all P<0.05). This is the first study to examine association between bone marrow radiation doses from the Chornobyl accident and clinical manifestations of the CLL in Chornobyl cleanup workers. The current study provides new evidence on the association of radiation dose and younger age at first radiation exposure at Chornobyl with shorter survival after diagnosis. Future studies are necessary with more cases in order to improve the statistical power of these analyses and to determine their significance.

Cancers after Chornobyl: From Epidemiology to Molecular Quantification

“…In addition to CLL risk estimates, it was defined that older age at first exposure, smoking, and higher frequency of visits to the doctor were significantly associated with a shorter latent period. At the same time, the association of radiation dose and younger age at first radiation exposure at Chornobyl with shorter survival after diagnosis was shown, though not statistically significant [27].…”

Clinical Risks for Chronic Lymphocytic Leukemia

“…48 More recent epidemiologic studies have implicated radiation at Chernobyl in CLL risk among clean-up workers, 49 and suggested a dose-dependent increase in the risk of death from CLL in this population. 50 Systematic studies on other environmental exposures are limited. A case-control study from Germany investigated occupational risk factors for high-grade lymphoma, low-grade lymphoma, or CLL.…”

30 years After the Chernobyl Nuclear Accident: Time for Reflection and Re-evaluation of Current Disaster Preparedness Plans

“…We also recently reported that higher radiation doses and younger age at first exposure to radiation during Chernobyl cleanup work were associated with significantly shorter survival of CLL cases. 21 The median age at diagnosis was 57 years compared to the median age at diagnosis in the U.S. of 72 years. 22 Further investigations are needed to develop a better understanding of the association between radiation and CLL, which is the most common type of leukemia in this cleanup worker population.…”