Diagnosis of benign and malignant thyroid disease in the East Kazakhstan Region of the Republic of Kazakhstan: A case review of pathological findings for 2525 patients

From 1949 to 1989, more than 470 nuclear weapons were tested by the former Soviet Union at the Semipalatinsk Test Site (STS) near Semipalatinsk City, East Kazakhstan Region, Republic of Kazakhstan. To investigate the possible relationship between radioiodine exposure and thyroid gland abnormalities, we conducted a case review of pathological findings of 2525 urban and rural patients who underwent surgery from 1966-94. Cases were comprised of 190 (7.5%) men and 2335 (92.5%) women. There were 1595 (63.2%) cases of goiter, most of which were multinodular; 348 (13.8%) cases of thyroid adenoma; 312 (12.4%) cases of Hashimoto's thyroiditis; 220 (8.7%) cancers; 15 (0.6%) cases of Riedel's thyroiditis; 9 (0.4%) de Quervain's thyroiditis cases, 1 (0.04%) lymphoma and 24 cases of other thyroid conditions consisting of tuberculosis, cyst, and hematoma. There was a noticeable increase in the number of cases of Hashimoto's thyroiditis and thyroid cancer from 1982-94. Among histological forms of thyroid cancer, papillary (47.3%) and follicular (33.2%) predominated. In later periods (1987-94), an increased frequency of abnormal cases occurred among patients less than 40 years of age, with the highest proportion among patients below 20. Given the positive findings of a significant cancer-period interaction, and a significant trend for the proportion of cancer to increase over time, we recommend analytic etiologic studies of thyroid disease among populations exposed to radioiodines from the STS.