Sickness rate and prevalence of thyroid cancer in a specific region of Ukraine 30 years after Chernobyl disaster

Background
The study aimed to determine the effect of iodine deficiency and increased radiation on morbidity of thyroid cancer in patients living in the Ternopil region of Ukraine. The task was solved by comparing the patients with thyroid cancer from the district areas with iodine deficiency and increased radiation with those coming from the regions with normal iodine content and a normal radioactive background.

Material and methods
The area of the Ternopil region was divided into the following 1) the northern area, with sufficient iodine content in food, radiation background – 0.09 mcSv/h; 2) the central and western areas, endemic in terms of iodine content and increased background radiation (up to 0.13 mcSv/h); and 3) the southern area, with sufficient iodine but increased background radiation (up to 0.15 mcSv/h). To conduct the analysis and determine the sickness rate, the patients were grouped depending on sex and age.

Results
The sickness rate and prevalence of thyroid cancer in males in 2016 were 4-6 times lower when compared to females in all areas. The sickness rate of the females in the areas with increased radiation turned out to be age-dependent with a 1.25-3.2 times increase when compared to the areas with normal conditions. In the areas of the increased background radiation and dietary iodine insufficiency, the sickness rate of females was 1.54-5.4 times higher than the index in the areas with normal conditions.

Conclusions
The highest rates prevalence and sickness rate of thyroid cancer in Ternopil region of Ukraine were observed in women over 51 years. The prevalence was 2 times, and the sickness rate 3 times higher in women over 51 years in the areas with iodine deficiency and an increased radiation background when compared to those in the areas with normal iodine and radiation background.