Background: Cancer risks following low and low-dose-rate exposure to ionising radiation require further scientific investigation. A pilot research project, supported by the Federal Office of Radiation Protection (BfS, Germany), is focused on a large cohort construction to provide a comprehensive assessment of cancer and non-cancer risks in the population affected by nuclear weapons atmospheric tests at the Semipalatinsk nuclear test site (SNTS), using health monitoring data accumulated during more than 70 years of follow-up.  
Materials and methods: A register of the affected population constructed and maintained at the Scientific Research Institute of Radiation Medicine, NCJSC Semey Medical University (SRIRME SMU), Semey, Kazakhstan, was used for study cohort enumeration and construction. All-cause mortality data were used to define study outcomes (all solid cancers, site-specific cancers, haematological malignancies). Initial data analyses included study cohort description, and calculation of standardised mortality rates (SMRs) for all cancer deaths using sex-, and age- specific cancer mortality rates for unexposed population of the Republic of Kazakhstan.  Using whole body radiation exposure doses reconstructed for a subcohort of the affected population, radiation-related cancer risk analysis is currently underway.          
Results:  A cohort of 53,000 individuals affected by the atmospheric nuclear weapons tests at the Semipalatinsk nuclear weapons test site performed in 1949-1962, was comprised. The cohort includes people born through 02.07.1963 and resided some time in one of 119 settlements contaminated by radioactive fallout.  The cohort has all-cause mortality follow-up on the territory of present Abai region starting from the date of first nuclear test that is 29.08.1949 or date of birth if happened after the date of the first test, and continuing through 31.12.2019 or the date of death or last known vital status whichever date came first.
SMR estimates for malignant neoplasms in the cohort were statistically significantly higher compared to the Kazakhstan general population; the mortality rates were significantly higher in male and female as well as in rural and urban cohort members compared with the national statistics.
The cohort comprises several groups of exposed people making possible assessment of radiation exposure effects at different lifetime windows, namely in utero, early life including neonatal period, childhood, adolescence, adulthood, old age (senility). A part of the cohort members can be unexposed offspring born to exposed parents. All the cohort composition features provide a unique opportunity to evaluate and compare radiation-related risks of cancer considering different radiosensitivity of the study population categories.
Conclusion: This is an important effort providing an opportunity to comprehensively assess cancer risks in the populations affected at different ages by radioactive fallout from the SNTS nuclear weapons testing programme. Scientific information received from the study will help to address public anxiety and fears concerning the health status of the affected people and their offspring as well to inform public health authorities performing medical follow-up of the exposed individuals.