NA cohort study of thyroid cancer and other thyroid diseases after the Chernobyl accident

Abstract

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 fine‐needle 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 (1998‐2000), 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.

Histopathological features of papillary thyroid carcinomas detected during four screening examinations of a Ukrainian-American cohort

“…As a result of the 4 screening examinations, 904 individuals were referred for fine needle aspiration biopsy (FNAB), and 849 (94%) complied between 1998 and 2008. All individuals who had a large, multinodular goiter or whose FNAB report indicated one of the following: ‘cancer', ‘suspicious for cancer', ‘follicular neoplasm', or ‘suspicious for follicular neoplasm' ( Bozhok et al , 2009 ) were referred for thyroid surgery ( n =196). By 31 December 2008, 167 individuals (85%) had undergone surgery.…”

“…A recent Belarusian-American thyroid screening study (BelAm) reported that higher 131 I doses were associated with a higher frequency of solid or diffuse-sclerosing variants of PTC and histopathological features of cancer aggressiveness, such as lymph vessel invasion, intrathyroidal spreading, and multifocality ( Zablotska et al , 2015 ). We previously reported the results of a detailed histopathological analysis, without considering individual 131 I doses, of 56 thyroid carcinomas diagnosed in a Ukrainian-American cohort (UkrAm) in the first cycle of thyroid screening examinations conducted during 1998–2000 ( Bogdanova et al , 2006 ; Bozhok et al , 2009 ). The BelAm and UkrAm studies had similar designs, methods of screening, and estimations of 131 I dose ( Stezhko et al , 2004 ; Tronko et al , 2006 ).…”

Are Risk Factors Common to Thyroid Cancer and Nodule? A Forty Years Observational Time-Trend Study

“…In 2 studies, each comparing relatively contaminated areas far from Chernobyl, with a control group in more distant uncontaminated areas, no difference was found in children or adolescents, with a ratio of TN subjects/investigated subjects varying from 2% to 6% [24] , [25] . Among children and adolescents exposed (0.79 grays) to 131 I after Chernobyl and evaluated 12 to 14 years later, TN was found in 2.7%, with 12% harboring TC [26] . Reiners reported a progressive increase of TC incidence in irradiated children and adolescents up to 10 or 15 years after the accident; however he did not describe TN incidence [27] .…”

Radiation Dose Does Not Affect the Predictive Value of Thyroid Biopsy for Diagnosing Papillary Thyroid Cancer in a Belarusian Cohort Exposed to Chernobyl Fallout

“…In a general population not exposed to radiation, FNAB has a high predictive value for diagnosing thyroid cancer in both adults [11][12][13][14][15] and children [16][17][18][19][20][21], while reported outcomes in irradiated subjects differ according to level and type of radiation exposure [22][23][24][25][26][27][28][29][30][31]. Following highdose external exposure to X-rays or after 131 I treatment of hyperthyroidism, the predictive value of FNAB for diagnosing thyroid cancer is substantially lowered by cellular atypia [22][23][24][25], while among children and adolescents exposed to lower X-ray doses used to treat benign conditions of the head and neck the predictive value is closer to that found in unexposed populations [26].…”

“…Following highdose external exposure to X-rays or after 131 I treatment of hyperthyroidism, the predictive value of FNAB for diagnosing thyroid cancer is substantially lowered by cellular atypia [22][23][24][25], while among children and adolescents exposed to lower X-ray doses used to treat benign conditions of the head and neck the predictive value is closer to that found in unexposed populations [26]. Information concerning internal exposure to environmental doses of radioiodines is not as robust [27][28][29][30][31]. The earliest cytologic studies of Chernobyl children suggested that most nodules were non-neoplastic, primarily chronic thyroiditis and cysts [27], and that the main diagnostic features of the PTCs were largely similar to those in unexposed adults [28].…”