| Ostapenko et al., Minsk, Belarus, and New York, NY, USA, evaluated 5,965 subjects who were less than 18 years of age at the time of the Chernobyl accident and who were living in contaminated areas. Anti-TPO and/or anti-Tg were present in 6.3% of subjects (F/M = 2/1). Anti-TPO only was seen in 3%, anti-Tg only in 1.7% , and anti-TPO + anti-Tg in 1.6% of subjects. In females the prevalence of circulating antibodies was highest being 13.1%. The prevalence of autoantibodies increased with thyroid volume and was present in 10.4% of subjects with multinodular goiter and 18.5% in subjects with thyroid carcinoma. (Comment: This study shows again that not only thyroid carcinoma is increased in children exposed to radioactive fall-out but also autoimmune thyroiditis.) Similar findings were reported by Petrenko et al., Minsk, Belarus. They found a prevalence of both TPO antibodies and Tg antibodies of 6.23% in a cohort of 5,179 subjects living in the Gomel district at the time of the accident. The group of 323 subjects with circulating autoantibodies was subdivided in 3 groups depending on the dose radioactivity received: A) >30 cGy; B) 30-100 cGy, and C) >100 cGy. All these subjects were living in an area of mild iodine deficiency. Both in group A and C a positive correlation was found between the level of TPO antibodies and serum TSH. This relationship was not present in group B. Despite this latter aspect these preliminary data suggest a causal relationship between the dose of radioactivity absorbed by the thyroid and the magnitude of autoimmune thyroiditis. Reiners et al., Würzburg, Germany, and Minsk, Belarus, reported that since the Chernobyl accident the incidence of thyroid carcinoma in children increased from 0.2 to 4.0 cases per 100,000 in 1995. Since 1996 this incidence is decreasing in children but still increasing in adults: from 2.1 in 1996 to 10.7 in 1999 per 100,000 adults. Between April 1993 and March 2000, 199 children from Belarus with advanced thyroid carcinoma were operated and subsequently treated with 131-I. In 99% papillary carcinoma was found and in 1% follicular carcinoma. Up to now, 169 children received one or more treatments with 131-I. In 142/169 (84%) children a complete remission was reached, 68% of these children having distant metastases. In the remaining 16% a partial remission was observed. The authors conclude that in these children the prognosis of treated carcinoma is relatively good. (Comment: From this report it is inferred that these tumors readily take up radioactive iodine.) Shakhtarin et al., Obninsk, Russia, evaluated the combined effect of iodine deficiency and irradiation to the thyroid in 3 groups of children between 7 and 14 years of age: group 1 consisted of 1,305 girls and 1,255 boys who were living in an area of mild iodine deficiency (median urinary iodine excretion 7.5-10 mg/dl) and were not exposed to radioactive fall-out; group 2 consisting of 449 girls and 439 boys lived in an area of similar iodine deficiency but received irradiation to the thyroid; group 3 consisting of 494 girls and 467 boys received an equal dose of radioactivity as group 2 but iodine deficiency of the area was more severe (median urinary iodine excretion 5.0-7.5 mg/dl). In group 1, diffuse goiter occurred in girls and boys in 7.7% and 7.3% and nodular goiter in 0.6% and 0.2% respectively. In group 2 these figures are 22% and 23.2%, and 1.8% and 2.5%, while in group 3 they were 35.8% and 31.3%, and 3.8% and 3.2%. (Comment: From these figures one can calculate that the effects of iodine deficiency and irradiation on the development of these thyroid disorders are rather additive than synergistic, while gender is equally affected.) Williams et al., Cambridge, UK, Minsk, Belarus, and Kiev, Ukraine, reported that after the Chernobyl accident the observed/expected (O/E) ratio of carcinoma reached a plateau of about 70 in 1997. Ninety-six percent of tumors were papillary carcinomas, the majority showing a largely solid and follicular pattern (SF) and the minority the classic papillary architecture (C). In post-Chernobyl children the proportion of C-type increased with age at operation but remained at less than a quarter of all papillary carcinomas, i.e. much less than found in non-exposed tumors. The SF morphology correlates with ret/PTC3 rearrangement. This type is more likely to cause rapid progression of the tumor. Follicular carcinomas show a small recent increase, maybe because this tumor has a longer latent period than papillary carcinoma. Thus, the incidence of follicular carcinoma may remain increased. Saenko et al., Nagasaki, Japan, Pisa, Italy, and Obninsk, Russia, similarly show a prevalence of ret/PTC rearrangements in thyroid papillary carcinomas after the Chernobyl accident. They find however a slightly lower prevalence in Russian children as compared to children from Belarus and Ukraine. Bazyltchik et al., Minsk, Belarus, and Würzburg, Germany, tested intellectual development in a group of 235 children from the Gomel region who were exposed to radioactive fall-out after the Chernobyl accident. These children were exposed either in utero or between the age of 0-1.5 years. Results were compared with a group of 105 children from a non-irradiated area. The exposed children were grouped according to the irradiation dose received and results of intellectual performance were tested in these 3 groups. The mean thyroid dose in children with an IQ =110 was 34.6 cGy; in the group with an IQ 90-109, 68.2 cGy, and in the group IQ <90, 78 cGy. Results between group 1 and group 2, and group 2 and group 3 were all significant p<0.01 and p<0.001 respectively. The mean IQ was significantly higher in children who received a dose <50 cGy (n = 61) as compared to children who received a dose >50 cGy (n = 52), 100.0 Points vs 71.7 points respectively (p<0.01). The authors could not find any thyroid function abnormality as assessed on the basis of TSH, FT4 and FT3 in any of these groups. They state that further studies including TRH testing and analysis of any differences in social economic environment could explain these differences in intellectual development. |
