post-Chernobyl Thyroid Carcinoma Research Articles

Post-surgical ablation of thyroid residues with radioiodine in Ukrainian children and adolescents affected by post-Chernobyl differentiated thyroid cancer.

Post-surgical ablation of thyroid residues with 131-iodine (131-I) is usually recommended after near-total thyroidectomy in high-risk patients, including children, with differentiated thyroid cancer (DTC). We report here the results of post-surgical radioiodine thyroid ablation in 249 children and adolescents of Ukraine with post-Chernobyl DTC initially treated with near-total thyroidectomy at the Institute of Endocrinology and Metabolism in Kiev, during a 2-year period. The patients' age at the time of the Chernobyl accident (1986), ranged from <1 to 14 yr in 223 subjects (children) and from 15 to 18 yr in 26 subjects (adolescents). Six weeks after surgery a diagnostic 131-I whole body scan revealed the presence of residual thyroid tissue in all cases. All patients received one or more courses of radioiodine therapy, for a total of 468 courses. One hundred and twenty-nine out of 249 patients (51.8%) were successfully ablated. The total number of treatment courses needed in these patients was 219. Most patients required multiple doses of radioiodine, only 63 required a single dose. One hundred and twenty patients (48.2%) treated with radioiodine were not ablated and are still under treatment program. The clinical features and the amount of thyroid residue were not different in ablated or not-ablated patients. Our results indicate that in this particular population of post-Chernobyl thyroid carcinomas, thyroid ablation is a rather difficult task. Only 51.8% were successfully ablated. Possible explanation for this finding may be the young age of the patients, other particular features of post-Chernobyl thyroid carcinoma or technical aspects, such as less radical surgical procedures.

Thyroid consequences of the Chernobyl nuclear accident.

It is well recognized that the use of external irradiation of the head and neck to treat patients with various non-thyroid disorders increases their risk of developing papillary thyroid carcinoma years after radiation exposure. An increased risk of thyroid cancer has also been reported in survivors of the atomic bombs in Japan, as well as in Marshall Island residents exposed to radiation during the testing of hydrogen bombs. More recently, exposure to radioactive fallout as a result of the Chernobyl nuclear reactor accident has clearly caused an enormous increase in the incidence of childhood thyroid carcinoma in Belarus, Ukraine, and, to a lesser extent, in the Russian Federation, starting in 1990. When clinical and epidemiological features of thyroid carcinomas diagnosed in Belarus after the Chernobyl accident are compared with those of naturally occurring thyroid carcinomas in patients of the same age group in Italy and France, it becomes apparent that the post-Chernobyl thyroid carcinomas were much less influenced by gender, virtually always papillary (solid and follicular variants), more aggressive at presentation and more frequently associated with thyroid autoimmunity. Gene mutations involving the RET proto-oncogene, and less frequently TRK, have been shown to be causative events specific for papillary cancer. RET activation was found in nearly 70% of the patients who developed papillary thyroid carcinomas following the Chernobyl accident. In addition to thyroid cancer, radiation-induced thyroid diseases include benign thyroid nodules, hypothyroidism and autoimmune thyroiditis, with or without thyroid insufficiency, as observed in populations after environmental exposure to radioisotopes of iodine and in the survivors of atomic bomb explosions. On this basis, the authors evaluated thyroid autoimmune phenomena in normal children exposed to radiation after the Chernobyl accident. The results demonstrated an increased prevalence of circulating thyroid antibodies not associated with significant thyroid dysfunction. This finding is consistent with the short period of follow-up, but it is highly likely that these children will develop clinical thyroid autoimmune diseases in the future. Therefore, screening programmes for this at-risk population should focus, not only on the detection of thyroid nodules and cancer, but also on the development of thyroid autoimmune diseases.

Post-Chernobyl Thyroid Carcinoma in Belarus Children and Adolescents: Comparison with Naturally Occurring Thyroid Carcinoma in Italy and France

Post-Chernobyl Thyroid Carcinoma in Belarus Children and Adolescents: Comparison with Naturally Occurring Thyroid Carcinoma in Italy and France

Pediatric thyroid cancer after the Chernobyl disaster. Pathomorphologic study of 84 cases (1991-1992) from the Republic of Belarus.

During the initial period after the Chernobyl accident, large amounts of radioactive iodine were released in fallout, resulting in serious exposure to the thyroid gland in the residents of areas around the nuclear power station. Beginning in 1990, a definite increase in the incidence of thyroid cancer was noted in children of the Republic of Belarus. Morphologic and clinical features of 84 cases of post-Chernobyl thyroid carcinoma in Belarussian children from 5 to 14 years of age are reported. The latent period for tumor development was 4-6 years, with a mean of 5.8 years. Papillary carcinoma was found in 83 patients and medullary carcinoma in one. Besides typical papillary carcinoma (14%), solid (34%), follicular (33%), mixed (10%), and diffuse sclerosing (9%) variants were observed. The follow-up period ranged from 8 months to 2.5 years. One patient died, local recurrence developed in 2, and cervical lymph node metastases developed in 10. To date, the incidence of local recurrence or metastatic disease after surgery was significantly higher in patients 5-8 years of age and in residents of areas nearest to the Chernobyl station. Post-Chernobyl pediatric thyroid carcinoma is characterized by a short latency, a higher proportion of tumors arising in young children, and an almost equal sex ratio. Microscopically, these tumors were usually aggressive, often demonstrating intraglandular tumor dissemination (92%), thyroid capsular and adjacent soft tissue invasion (89%), and cervical lymph node metastases (88%). Papillary carcinoma was diagnosed in 99% of cases, with an unusually high frequency of solid growth patterns. Morphologic changes in nonneoplastic thyroid tissue were present in 90% of the glands, and the most specific findings were vascular changes and perifollicular fibrosis.