Cancers after Chornobyl: From Epidemiology to Molecular Quantification

Abstract

An overview and new data are presented from cancer studies of the most exposed groups of the population after the Chornobyl accident, performed at the National Research Center for Radiation Medicine (NRCRM). Incidence rates of solid cancers were analyzed for the 1990–2016 period in cleanup workers, evacuees, and the general population from the contaminated areas. In male cleanup workers, the significant increase in rates was demonstrated for cancers in total, leukemia, lymphoma, and thyroid cancer, as well as breast cancer rates were increased in females. Significantly elevated thyroid cancer incidence was identified in the male cleanup workers cohort (150,813) in 1986–2012 with an overall standardized incidence ratio (SIR) of 3.35 (95% CI: 2.91–3.80). A slight decrease in incidence rates was registered starting at 25 years after exposure. In total, 32 of 57 deaths in a group of cleanup workers with confirmed acute radiation syndrome (ARS) or not confirmed ARS (ARS NC) were due to blood malignancies or cancer. Molecular studies in cohort members included gene expression and polymorphism, FISH, relative telomere length, immunophenotype, micronuclei test, histone H2AX, and TORCH infections. Analysis of chronic lymphocytic leukemia (CLL) cases from the cohort showed more frequent mutations in telomere maintenance pathway genes as compared with unexposed CLL patients.

Cancer incidence among Chernobyl cleanup workers from Estonia: A 34‐year follow‐up

“…Unfortunately, cohort studies of cleanup workers from different countries cannot be accurately compared because of differences in reporting, registration, follow-up and analyses; mortality vs incidence outcomes; special health screenings or not; available information on cofactors (eg, education, ethnicity, smoking); methods of radiation dose determination; and effect measures such as SIR, SMR, excess relative risk per dose unit. [22][23][24] For example, the Russian cohort of 67 568 Chernobyl cleanup workers reported a statistically significant dose response for all incident solid cancers based on official recorded doses (arithmetic mean of 13 cGy) and over the follow-up period 1992 to 2009. 25 However, no attempt was possible, as the authors recognized, to estimate the impact of behavioral factors on cancer risk: "As a weakness of the present study, the analyses did not take into account recognized risk factors such as smoking, alcohol consumption, genetic predisposition, marital status, education, occupational status."…”

“…Our results are in accord with recent observations by Smailyte et al 21 showing increased risk of cancer sites related to smoking and alcohol use in the cohort of Lithuanian Chernobyl cleanup workers followed in 1986 to 2012. Unfortunately, cohort studies of cleanup workers from different countries cannot be accurately compared because of differences in reporting, registration, follow‐up and analyses; mortality vs incidence outcomes; special health screenings or not; available information on cofactors (eg, education, ethnicity, smoking); methods of radiation dose determination; and effect measures such as SIR, SMR, excess relative risk per dose unit 22‐24 . For example, the Russian cohort of 67 568 Chernobyl cleanup workers reported a statistically significant dose response for all incident solid cancers based on official recorded doses (arithmetic mean of 13 cGy) and over the follow‐up period 1992 to 2009 25 .…”

Analysis of immunoglobulin heavy variable chain rearrangement in chronic lymphocytic leukemia patients among Chornobyl clean-up workers

“…The question of the radiogenicity of B-cell chronic lymphocytic leukemia (CLL) remains largely controversial, although a number of epidemiological studies have shown an elevated radiation-associated risk for CLL [1][2][3]. Besides, CLL is the most common form of leukemia among clean-up workers of Chornobyl Nuclear Power Plant accident [2,4].…”

Editorial: Translational research in thyroid cancer, Volume II

“…Excess cases of thyroid cancer in exposed children were first detected after the accident in 1990. Such cases are continuing to accumulate, albeit at a much slower rate, now more than 30 years later ( 4 , 5 ). Bogdanova et al.…”