Host: The Japan Radiation Research Society
Co-host: Asian Association for Radiation Research
Radiation Effects on thyroid were studied through the thyroid health examinations for the exposed people in Semipalatinsk and Hiroshima from 1999, using thyroid hormones (FT3,FT4,TSH) and thyroid autoimmune antibody (TgAb) in blood, iodine in urine and aspiration biopsy cytology of thyroid, and histopathology. In the nontumorous tissues of thyroid cancer cases, fibrosis thought be affected by expose seemed to be more pronounced in the exposed people in Semipalatinsk than that in Hiroshima. Urinary iodine level for Semipalatinsk people was lower than for Hiroshima people. Chronic thyroiditis was estimated not related to radiation expose. Rate of hypothyroidism was suspected higher in the most exposed village people in Semipalatinsk, and in the nontumorous thyroid lesions, nuclear abnormalities of micronucleus tended to be higher in those highly exposed villagers in Semipalatinsk. In Hiroshima, micronucleus was found in the nontumorous lesions of thyroid among the A-bomb exposed survivors in the cases of Hashimoto disease. Our urinary iodine level examined after one-week staying in Kazakhstan shoed apparent decrease. Thyroid stimulating hormone receptor (TSHR) sensitivity of noncancerous lesions of thyroid showed significant decrease with the increase of age (14-89 rears old). Amount of estrogen receptors in nontumorous tissues of thyroid cancer cases examined for female also decreased with age increasing. These data proved the truth of the hypothesis of oncology model of thyroid cancer development following irradiation, proposed by Takeichi in 1993.
