Joint Belarus/Russia/EU/IARC/SMFH case-control studies of thyroid cancer in young people following the Chernobyl accident

In 1996, following several years of collaborative international studies of the consequences of the Chernobyl accident, a number of groups proposed to carry out case-control studies of thyroid cancer among young people in contaminated territories of Belarus and Russia. Collaborations were set-up between the participants of the Chernobyl Sasakawa Project and of those of the Belarus/Russia/EU/IARC project. These involved joint field work and dose reconstruction, although both projects maintained their original objectives: to evaluate the risk of I-131-induced thyroid cancer and to study the role of possible modifying factors in radiation carcinogenesis, in particular, iodine deficiency and supplementation and genetic predisposition. Joint data collection is now virtually finished and dose reconstruction is nearing completion. Final results are expected in 2002. The current paper summarises the objectives and methods of the case-control studies, as well as the very preliminary results based on joint data collection and analyses. These appear to indicate that cases were likely to have received higher doses from I-131 on average than controls. The collaboration has resulted in the collection of one of the largest sources of data on thyroid cancer risk in children, adolescents and young adults exposed to ionising radiation. Results from this work are likely to have important implications for radiation protection in general, as well as for public health actions among exposed populations in the CIS.