Breast cancer incidence in the regions of Belarus and Ukraine most contaminated by the Chernobyl accident: 1978 to 2016.

Even 30 years after the accident, an association between breast cancer incidence and ionizing radiation exposure from Chernobyl fallout remains uncertain. We studied breast cancer incidence in the most contaminated regions of Belarus (Gomel and Mogilev) and Ukraine (Kyiv, Zhytomyr and Chernihiv) before (1978-1986) and after (1987-2016) the accident. Breast cancer cases and female population size data were received from the national cancer registries and the state departments of statistics. The study included 85 132 breast cancers with 150 million person-years at risk. We estimated annual rayon (district)-average absorbed doses to the breast from external and internal irradiation of the adult female population over the period of 1986-2016. We studied an association between rayon-average cumulative absorbed breast dose with 5-year lag, that is, excluding the exposure in 5 years prior to breast cancer diagnosis, and breast cancer incidence using negative binomial regression models. Mean (median) cumulative breast dose in 2016 was 12.3 (5.0) milligray (mGy) in Belarus and 5.7 (2.3) mGy in Ukraine, with the maximum dose of 55 mGy and 54 mGy, respectively. Breast cancer incidence rates statistically significantly increased with calendar year and attained age, and were higher in urban than in rural residents. Adjusting for time, age and urbanicity effects, we found no evidence of increasing incidence with rayon-average 5-year lagged cumulative breast dose. Owing to ecological study design limitations, a case-control study covering this area with individually reconstructed absorbed breast doses is needed testing for association between low-dose protracted radiation exposure and breast cancer risk after Chernobyl.

Trends in incidence, mortality and survival of testicular cancer patients in Belarus.

INTRODUCTION: The objective of this study was to assess recent trends in incidence, mortality and relative survival (RS) in testicular cancer (TC) patients in Belarus and to provide international comparisons of our figures. MATERIAL AND METHODS: We surveyed the Belarusian Cancer Registry for all male cases diagnosed with International Classification of Diseases for Oncology, third edition (ICD-O-3) topography code C62 between 1990 and 2015. Trends for incidence and mortality rates per 100,000 of the world standard population and annual percentage changes (APCs) were calculated. We also estimated the 1- and 5-year RS rates for the 1990-1998, 1999-2007 and 2008-2015 periods according to the Ederer II method. The RS estimates for the 2008-2015 period were age-standardized and compared with the published EUROCARE-5 data and SEER-18 database analysis. RESULTS: A total of 2,500 and 2,439 cases were included into incidence and survival analyses, respectively. We found a significant increase in the TC age-standardized incidence rate (APC 2.6%) and a decline in the age-standardized mortality (APC -3.0%) over the study period. RS significantly increased in all patients` strata; a relative increase was more pronounced in advanced stages of seminoma and younger age groups. Nevertheless, the most recent figures of age-standardized RS including stage-specific estimates were generally worse than the European and SEER data. CONCLUSIONS: We have found a significant increase in TC incidence in Belarus in recent years. Mortality has significantly declined with a corresponding increase in RS which, however, did not reach European or North American figures. Continued effort is required to improve the quality of management of TC patients in our country.