Cancers after Chornobyl: From Epidemiology to Molecular Quantification

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

From 1986 to 1991, 4831 men from Estonia were sent to clean up radioactively contaminated areas near Chernobyl (Chornobyl). Their cancer incidence during 1986 to 2019 was compared to that of the male population of Estonia. The cohort of cleanup workers was linked to national population and cancer registers based on unique personal identification numbers. Nineteen (0.4%) workers could not be traced. A total of 4812 men contributing 120 770 person-years of follow-up were eligible for the analyses. Standardized incidence ratios (SIR) and adjusted relative risks (ARR, expressed as ratios of SIRs) with 95% confidence intervals (CI) were calculated. A total of 687 incident cancer cases were registered in the cohort (SIR 1.11, 95% CI 1.03-1.19). Presumptive radiation-related cancers combined were in excess, but not when smoking- and alcohol-related cancers were excluded (SIR 0.92, 95% CI 0.71-1.18). For smoking-related cancers, the SIR was 1.24 (95% CI 1.13-1.36) and for alcohol-related cancer the SIR was 1.53 (95% CI 1.31-1.75). Less educated workers had a higher risk of all cancers (ARR = 1.21, 95% CI 1.02-1.44) and smoking-related cancers (ARR = 1.42, 95% CI 1.14-1.76). An elevated risk of alcohol-related cancers was evident 15 to 24 years (vs <15 years) after return from the Chernobyl area. This updated register-based follow-up of Chernobyl cleanup workers from Estonia revealed an excess of radiation-related cancer sites combined, but the excess was not apparent after excluding cancers associated with smoking and alcohol.

Inadvertent Radiation Exposures in Combat Zones: Risk of Contamination and Radiobiologic Consequences

On February 24, 2022, Russia began a military invasion of Ukraine. Missile and air strikes were reported throughout the country, shortly followed by a large ground invasion from multiple directions. Four major theaters developed: the Kyiv offensive, the Northeastern Ukraine offensive, the Eastern Ukraine offensive, and the Southern Ukraine offensive, with continued missile and air strikes far into Western Ukraine. Advancing Russian military units launched an attack and captured the Chernobyl nuclear station. Russian troops dug trenches into the area commonly known as the "Red Forest," violating the established radiation safety measures and threatening security within the Chernobyl Exclusion Zone. The placement of military units in such close proximity to the station also sparked concerns of possible damage occurring to the containment vessel constructed around the station's wrecked fourth reactor. There are 15 operating nuclear reactors in Ukraine. Each is vulnerable to an attack or sabotage that could precipitate a malfunction and possible release of radioactive isotopes. In this short commentary, we will discuss radiobiologic data obtained after the analysis of historical nuclear power plant (NPP) accidents and emphasize new challenges for nuclear security when NPPs are found and are possible targets within a conflict zone.

EXPRESSION OF LIPOPROTEIN LIPASE AND c-MYC ONCOGENE IN PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA AFFECTED BY THE CHORNOBYL ACCIDENT

OBJECTIVE

to determine the association between the expression of lipoprotein lipase (LPL) and c-MYC genes inperipheral blood cells of chronic lymphocytic leukemia (CLL) patients affected by the Chornobyl catastrophedepending on the mutational status of IGHV genes.

METHODS

Analysis was performed in the group of 69 CLL patients irradiated due to the Chornobyl NPP accident (58clean-up workers of 1986 year, 6 inhabitants of radionuclide contaminated areas, and 5 evacuees). The IGHV genemutational status was studied by polymerase chain reaction (PCR) followed by direct sequencing. LPL and c-MYCexpression was evaluated by Quantitative Real-time PCR. Data were analyzed with the SPSS software package, version 20.0.

RESULTS

Relative LPL expression levels in CLL samples ranged from 0 to 1663.5 (mean 138.47 ± 30.69, median 26.1).A strong correlation between individual LPL expression levels and IGHV mutational status was found (r = 0.684;p < 0.0001). The average relative c-MYC expression level was 5.7 ± 0.87 (median 2.86; range 0-48.5). No association between c-MYC expression and IGHV mutational status was found. Among unmutated IGHV cases, a correlationbetween LPL and c-MYC gene expression levels was identified: r = 0.351; p = 0.013.

CONCLUSIONS

Our data confirm the dominant concept that unmutated IGHV CLL cases are more sensitive to the actionof proliferative stimuli compared to mutated IGHV CLL cases. This is manifested by an increase in the expression ofa functionally significant LPL gene, is one for the strongest negative prognostic markers in CLL.