This study will be performed in view of the fact that the risk of thyroid disorders, and, particularly, thyroid cancer induced by I¹³¹ is still unknown though cancerogenic effect of X-ray and gamma-radiation has been demonstrated.

As a result of the accident a great amount of I¹³¹ and other iodine isotopes have been polluted into atmosphere and contaminated vast territories of different countries and effected to millions of people.

Correlation between thyroid cancer in childhood and adolescence and I¹³¹ following Chernobyl accident has not still received strict quantitative estimate in the form of accepted by world community models of radiation risk which are necessary for improving of systems of radiation protection in reactor accidents and forecasting of health effect.

The principal difference of planning work is that for the first time a cohort of subjects is created. The cohort includes individuals exposed to radiation in children and adolescent age and to whom thyroid doses (“direct measurements”) were measured in May-June of 1986. All individuals given consent to be included to the cohort will be examined in accordance with scientific protocol during 30 years in order to reveal thyroid cancer or other thyroid pathology. The volume of cohort is determined by a statistic power of the study and will be not less than 12 000 individuals. Patients will be completely examined including ultrasound examination of the thyroid, hormonal and biochemical tests. If necessary, fine needle biopsy of thyroid nodules and surgery with exact pathomorphological verification of diagnosis will be performed. Strict following the procedures of quality control will provide with reliable results while making diagnosis of disease and estimating individual exposure doses.

The results to be obtained in the Project will allow develop scientific procedure for long-term radiation-epidemiological cohort studies, providing a reliable information on radiation effects in a wide dose range with regard to the inducting of thyroid cancer and other disorders.

In the course of the Project it is planned to perform special medical examination of 6000 individuals to detect abnormalities of thyroid and parathyroid glands in those who were exposed to radiation in childhood and adolescence and for whom thyroid direct measurements were made in May-June of 1986.

Key role in the Project is belonged to the methods of searching and selection of cohort of given amount; methods of thyroid dose reconstruction, clinical-laboratory methods of making and verification of diagnosis of thyroid pathology.

Reconstruction of individual thyroid doses is based on the results of direct measurements performed in May-June of 1986 as well as on the results of individual interview of each subjects regarding behavior, nourishment, preventive measures during “iodine” period. Besides, to estimate the contribution of other radionuclides an information will be used of environmental contamination in the places of residence. To increase the accuracy of individual dose estimates it is studied the effect of radiometer probe location with respect to thyroid, possible effect of hair, skin, clothes, and whole body contamination to the readings of radiometer.

While examination of the cohort a complex of methods is used including endocrinologic examination, ultrasound examination of thyroid with recording and analyzing thyroid image, blood tests for estimation of hormonal status and biochemical indices, estimation of iodine content in urine to reveal the level of iodine deficiency. Depending the type of revealed pathology fine needle biopsy of thyroid nodules and cytological examination of the sample could be performed. If necessary, a patient could be referred to the specialized clinic of the Institute for verification of diagnoses or to surgery with further morphological examination of removed tissues.

All data received in the course of screening, referrals to examination, interview, clinical-laboratory, cytological, and pathomorphological examinations will be filled in special formats and entered into the computer data bases and then transferred to the central data base.

The project staff consists of specialists from different fields of science and has a long-term experience of work including those obtained in international programs performed under WHO and EC Projects.

The Partner – National Cancer Institute (USA) will provide with 100% funding. Technical approach and methodology have been worked out and agreed with the Partner.