J. Radiol. Prot. 26 (2006) 51–67 doi:10.1088/0952-4746/26/1/003

Our objective is to assess the regional and temporal dependences of the baseline cases contributing to thyroid cancer incidence among those exposed in childhood or during adolescence in Belarus and Ukraine after the Chernobyl
accident. Data are analysed for Kyiv and Sevastopol City and the 25 oblasts (regions) in Ukraine, and forMinsk and Gomel City and the 6 oblasts in Belarus.
Average thyroid doses due to the Chernobyl accident were assessed for every birth year in the period from 1968 to 1985. Case data pertain to people who underwent surgical removal of thyroid cancers during the period 1986 to 2001 and who were allocated to their place of residence at the time of the accident.
The 35 oblasts/cities were subdivided into an upper, middle and lower group of baseline thyroid cancer incidence. Poisson regressions were performed to estimate age, time and gender dependences of the baseline incidence rates in the three groups. The majority of oblasts/cities with high average doses and the majority of Belarusian oblasts/cities belong to the upper group of baseline thyroid cancer incidence. The baseline in the upper group is estimated to be larger than in the middle group by a factor of 2.3, and by a factor of 4.0 when compared to the lower group. The baseline incidence increases with age and with time since exposure. Estimated baseline incidence rates were found to increase from 1988 to 1999 by factors of three and two for the upper and the two lower groups respectively. The estimated thyroid cancer incidence rates in Belarus and Ukraine, and their dependences on gender and age, are consistent with observed rates found in the larger cancer registries of other countries. In conclusion, the baseline cases are found to contribute about 70% to the thyroid cancer incidence in Ukraine, and about 40% to the incidence in Belarus.

P Jacob1,7, T I Bogdanova2, E Buglova3,8, MChepurniy4, Y Demidchik5,
Y Gavrilin6, JKenigsberg3,9, JKruk3,10, C Schotola1, S Shinkarev6,
MDTronko2 and S Vavilov4
1 GSF—Institute of Radiation Protection, Neuherberg, Germany
2 Institute of Endocrinology and Metabolism of the Academy of Medical Sciences of Ukraine,
Kyiv, Ukraine
3 Research Institute of Radiation Medicine and Endocrinology, Minsk, Belarus
4 Ukrainian Radiation Protection Institute, Kyiv, Ukraine
5 Belarus State Medical University, Minsk, Belarus
6 State Research Center—Institute of Biophysics, Moscow, Russian Federation

7 Corresponding address: GSF National Research Center, Institute of Radiation Protection, D-85764 Neuherberg,
Germany.
8 Present address: International Atomic EnergyAgency, Vienna, Austria.
9 Present address: National Radiation Protection Commission, Minsk, Belarus.
10 Present address: Research Institute of Radiology, Gomel, Belarus.

E-mail: Jacob@gsf.de
Received 16 March 2005, in final form and accepted for publication
18 November 2005
Published 7 March 2006
Online at stacks.iop.org/JRP/26/51

http://iopscience.iop.org/0952-4746/26/1/003/pdf/jrp6_1_003.pdf