DIAGNOSIS OF BENIGN AND MALIGNANT THYROID-DISEASE IN THE EAST KAZAKSTAN REGION OF THE REPUBLIC OF KAZAKSTAN - A CASE REVIEW OF PATHOLOGICALFINDINGS FOR 2525 PATIENTS

From 1949 to 1989, more than 470 nuclear weapons were tested by the fo rmer Soviet Union at the Semipalatinsk Test Site (STS) near Semipalati nsk City, East Kazakhstan Region, Republic of Kazakhstan. To investiga te the possible relationship between radioiodine exposure and thyroid gland abnormalities, we conducted a case review of pathological findin gs 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; 3 48 (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 thyroidit is; 9 (0.4%) de Quervain's thyroiditis cases, 1 (0.04%) lymphoma and 2 4 cases of other thyroid conditions consisting of tuberculosis, cyst, and hematoma. There was a noticeable increase in the number of cases o f Hashimoto's thyroiditis and thyroid cancer from 1982-94. Among histo logical forms of thyroid cancer, papillary (47.3%) and follicular (33. 2%) predominated. In later periods (1987-94), an increased frequency o f abnormal cases occurred among patients less than 40 years of age, wi th 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 recommen d analytic etiologic studies of thyroid disease among populations expo sed to radioiodines from the STS.