Incidence of thyroid cancer and epidemiologic determinants of the condition: Role of ionizing radiation

Abstract

As a result of the Chernobyl accident, a significant part of Ukraine was contaminated with radionuclides. According to UNSCEAR, the activity of material released into the environment from the destroyed active zone of the reactor was about 50 MKi, among which the share of radionuclides of iodine, cesium and tellurium was 10-20%. Despite the fact that the prompt implementation of iodine prophylaxis made it possible to reduce the dose load on the thyroid gland, nevertheless, a significant part of the child and adult population received radiation doses of the thyroid gland, which pose a serious danger in the development of possible long-term oncological consequences. Based on dose calculations according to the most conservative model of single dose of radioactive iodine, the number of children living in the 8 most affected areas of Ukraine affected by iodine radionuclides and exposed to doses in excess of 200 cGy is estimated to be 12,000 or more, in the dose range up to 200 cGy - 79 500, up to 30 cGy - 38 000.
 Available information on thyroid doses in Ukraines population, on the one hand, and information on the carcinogenic effects of this organs radiation, accumulated to date in the world, on the other hand, indicate the need for carefully planned epidemiological studies aimed at assessing the risk of this pathology in victims. At the same time, the effectiveness of such studies, and, consequently, the development of preventive measures to reduce the effects of radiation in the future, will largely depend on taking into account the characteristics of the epidemiological study of the role of the radiation factor in the development of thyroid cancer.
 In connection with the foregoing, the aim of this work was to generalize the information accumulated to date in the world, reflecting deficiencies in the study of the epidemiology of radiation-induced thyroid cancer, as well as confirming the need for further development and improvement of these studies.