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BACKGROUND:The Ukrainian American Cohort Study was established to evaluate the risk of thyroid disorders in a group exposed as children and adolescents to 131I by the Chernobyl accident arithmetic mean thyroid dose, 0.79 grays. Individuals are screened by palpation and ultrasound and are referred to surgery according to fineneedle aspiration biopsy FNA. However, the accuracy of FNA cytology for detecting histopathologically confirmed malignancy after this level of internal exposure to radioiodines is unknown.METHODS:During the first screening cycle 19982000, 13,243 individuals were examined, 356 individuals with thyroid nodules were referred for FNA, 288 individuals completed the procedure, 85 individuals were referred to surgery, 82 individuals underwent surgery, and preoperative cytology was available for review in 78 individuals. Cytologic interpretation for the nodule that resulted in surgical referral was correlated with final pathomorphology; discrepancies were reviewed retrospectively; and the sensitivity, specificity, positive predictive value PPV, and negative predictive value NPV of FNA cytology were calculated.RESULTS:All 24 cytologic interpretations that were definite for papillary thyroid cancer PTC were confirmed histopathologically PPV, 100; and, of 11 cytologic interpretations that were suspicious for PTC, 10 were confirmed PPV, 90.9. Ten of 41 FNAs that were interpreted as either definite or suspect for follicular neoplasm were confirmed as malignant PPV, 24.4, including 2 follicular thyroid cancers and 8 PTCs all but 1 of the follicular or mixed subtypes. Depending on whether a cytologic interpretation of follicular neoplasm was considered “positive” or “negative,” the sensitivity was 100 and 77.3, respectively; similarly, the respective specificity was 17.6 and 97.1, the respective PPV was 61.1 and 97.1, and the respective NPV was 100 and 76.7.CONCLUSIONS:Among children and adolescents who were exposed to 131I after the Chernobyl accident and were evaluated 12 to 14 years later, thyroid cytology had a sensitivity and a predictive value similar to those reported in unexposed populations. Cancer Cancer Cytopathol 2009. Published 2009 by the American Cancer Society.