Mortality risk due to upper gastrointestinal cancers in Southern Urals population exposed to radiation cohort

   Cancer is one of the major late effects of exposure to ionizing radiation. Low dose effect has been still remains one of the most challenging issues.

   The objective of the study is to analyze the dose dependence of the risk of upper gastrointestinal cancer mortality in members of the Southern Urals Population Exposed to Radiation Cohort over the period from 1950 to 2020.

   Materials and Methods: Southern Urals Population Exposed to Radiation Cohort includes people aggrieved as a result of two radiation accidents in the Southern Urals. Follow up period is 71 years, cohort size at the end of the follow up is 62,259 individuals, number of person-years at risk – 1964,136. In total 1,587 upper gastrointestinal cancers have been revealed, 844 of them were found in men, and 743 – in women. Dose to the stomach was used as the reference one. Maximum dose over the whole follow up period made up 1.13 Gy, mean dose – 0.04 Gy. Statistical analysis has been performed with the Epicure software package using the Poisson regression with simple parametric model of the excess relative risk. Maximum likelihood method with 95 % probability was applied to evaluate the statistical significance of the results.

   Results and Discussion: The analysis of the mortality risk of all the upper gastrointestinal cancers revealed linear dose relationship which started to be observed already with 2-year minimum latency period: ERR 0.76/Gy, р = 0.03. Dose dependence of the mortality from oral cavity cancer was also linear with 2-year minimum latency period, ERR/Gy was 4.95, p = 0.01. The risk of the development of upper gastrointestinal cancers did not exhibit statistically significant dependence on dose to the stomach. The effect of modifying factors per unit of radiogenic risk has also been evaluated.

   Conclusion: Based on the results of the study, a statistically significant excess relative mortality risk of all cancers of the upper gastrointestinal and oral cavity has been obtained.

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