Prevalence of neoplastic thyroid disorders in territories close to Semipalatinsk nuclear test site, East Kazakhstan: a cross-sectional study

Maira Zh. Espenbetova, Ж К Заманбекова, Юрковская О.А., Жуманбаева Жанар Махмутовна, Амренова Куралай Шагановна, A. Espenbetov, Natalya Glushkova, A M Grjibovski

European Journal of Public Health, 2014

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DOI 10.1093/eurpub/cku166.115
Data confidence 70 medium
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Abstract

Background Thyroid tumors are the most common endocrine tumors. Thyroid gland is one of the most sensitive organs to carcinogenic effects of ionizing radiation. Semipalatinsk Nuclear Test Site (SNTS) was used by the Soviet military during more than 40 years resulting in substantial pollution of the large territory. The data on health status of the population living close to SNTS is very scarce. Our previous studies have presented the data on thyroid cancer in this population. The aim of this study was to assess the prevalence of benign thyroid disorders among the residents of settlements adjacent to SNTS. Methods A cross-sectional study. A total of 4083 people (1836 males and 2247 females) aged 16-84 years permanently living in Semey region (East Kazakhstan) with documented radiation exposure from 200 to 499 cSv of effective dose comprised the sample. Physical examination and ultrasound scan of thyroid glands were performed in all participants. Thyroid fine-needle aspiration procedure was used in those with ultrasound detected neoplasms with a diameter of 1 cm or larger. The prevalence is presented with 95% confidence intervals using Wilson’s method. Results The overall prevalence of neoplastic thyroid disorders in the full sample was 37.3% (95% CI: 35.8-38.8). The most common benign diagnoses detected were benign colloid nodules, multinodular goiter and thyroid cysts with a prevalence of 10.6% (95 CI: 9.7-11.5), 2.6% (95% CI: 2.1-3.1) and 0.8% (95% CI: 0.6-1.1), respectively. Altogether, 1.1% of the sample was diagnosed with malignant tumors corresponding to the prevalence of 1.1% (95% CI: 0.8-1.4). A subsequent histological examination has shown that 95.5% of the malignant tumors were papillary carcinomas. No geographic variations between the settings where the study was performed were observed. Conclusions The study has revealed a high prevalence of neoplastic thyroid disorders in the population living close to Semipalatinsk nuclear test site. The prevalence is substantially greater than in other regions of Kazakhstan. The study stresses the importance of regular medical examination of the population living on this territory and a need for development of rehabilitation activities for those who were exposed to radioactive pollution from SNTS. Key message The prevalence is substantially greater than in other regions of Kazakhstan and in neigbouring countries.