Radiation risk and screening effect of thyroid cancer incidence among the population of Bryansk and Orel oblasts of the Russian Federation

This paper continues the investigation of the radiological consequences of the Chernobyl accident. The study presents a method of radiation risks estimation of cancer of the thyroid gland (thyroid cancer) taking into account an effect of screening among the population exposed to internal exposure. The cohort selected for analysis consists of 309130 people from most contaminated territories of Bryansk and Orel oblasts affected by the Chernobyl accident. Over the follow-up period 1992-2011, a total of 1034 thyroid cancer cases were identified as the result of annual compulsory health examination (272 cases among children and adolescents 0-17 y of age at the time of the accident and 762 cases among adults older than 18 y of age at the time of the accident). The excess relative risk per 1 Gy (ERR/1Gy) is found to be statistically significant only for children and adolescents at the time of the Chernobyl accident (ERR/1Gy=4.60; 95% CI: 2.22; 8.25; p