Breast cancer incidence rates in women exposed to occupational ionizing radiation

Introduction. Breast cancer (BC) is one of the most common malignancies within female incidence and mortality patterns in the RF. Study objective. To analyze BC incidence in females exposed to occupational ionizing radiation over prolonged periods. Materials and methods. The study cohort included 5689 females who had been occupationally exposed to ionizing radiation throughout 1948-1982 and followed up until 31.12.2018. Results. BC was on the top of the list among females of the study cohort (11.9%). BC prevalence rate in the female cohort understudy was 28.3% as of 31.12.2018. The standardized BrCa incidence rate was 0.88 ± 0.07 per 1000 person-years of the follow-up. The absolute BrCa case increase in the females was 1.29, with the rise of 232.48% by the end of the follow-up due to the rise in age categories of females and the elevating risk of the disease occurrence. Discussion. The study cohort of females demonstrated standardized BrCa incidence rates consistent with the corresponding estimates for the general female population of the RF. Meanwhile, the observed rates were lower than those estimated for the female population of the Chelyabinsk region. The increasing trend of the standardized BC incidence rate by the end of the follow-up period (31.12.2018) was consistent with WHO statistics. The extended follow-up for an updated assessment of ionizing radiation effect on BC incidence is required to develop new cancer prevention strategies. Conclusion. The study demonstrated that BC incidence rates in the study cohort varied by age and calendar period of the follow-up. The increasing trend of the standardized rates of BC incidence was observed by the end of the follow-up.