Epidemiological assessment of mortality rates from malignant neoplasms of the lower gastrointestinal tract in the Ural cohort of the accident exposed population

Abstract

The study of the mortality rates from malignant neoplasms of the lower gastrointestinal tract in a cohort of chronically exposed population requires a comprehensive approach that would consider the duration of the follow-up, doses, demographic characteristics and other factors. The objective of the study is epidemiological assessment of mortality rates from malignant neoplasms of the lower gastrointestinal tract in the Ural cohort of the accident-exposed population. The study cohort consists of 62,591 individuals, the number of person-years of follow up – 1,964,092, the follow-up period is from 01.01.1950 to 31.12.2020. The cohort comprises people exposed in the Southern Urals over the period from 1950 to 1960. Analysis of the data was performed with statistical methods using the DATAB software module of the Epicure software package and the R package. Over a 70-year follow-up period 426 cases of malignant neoplasms of the lower gastrointestinal tract were registered. Maximum mortality rates were observed among cohort members aged over 60. Colon cancer mortality rates in men exceeded those in women but statistically significant differences were observed only in the age-group 60-79 years. The analysis of the time-dependent changes in mortality rate stated that it increased with every ten-year period of follow-up. At the same time, neither ethnicity, nor age at the start of exposure had a statistically significant effect on the mortality rate. The structure and the relationship between mortality rates from the malignant neoplasms of the lower gastrointestinal tract sex, follow-up period have been studied, ethnicity, age, including the age at the start of exposure. The obtained results will be used in the course of further studies of dose-dependence of colon cancer mortality.