Project for development of in vivo rat model internal 131-iodine exposure in thyroid grand

1986年切尔诺贝利核灾难后，那里儿童甲状腺癌的数量增加了。1991年至1996年，我们加入了切尔诺贝利·佐佐川健康和医疗合作项目。在5年的时间里，我们对13000多名儿童进行了筛查。儿童甲状腺癌的发病率是日本的100倍。不幸的是，我们没有这些患者在事故发生时的直接甲状腺剂量的数据。辐射和甲状腺癌之间的直接关系仍不确定。另一方面，以前的报告显示，在使用碘-131诊断或治疗的患者中，甲状腺癌的发病率没有增加。为了阐明放射性碘摄入是否会导致甲状腺癌，我们试图制作体内暴露于碘131的动物模型。将碘-131(0、0.2、0.6、1Mbq)分别注射给低碘饮食大鼠(n=10/组)。照射后1、2、6、12个月处死大鼠，进行病理学分析。我们观察到染毒大鼠的甲状腺肿瘤没有增加。这一结果没有带来任何具体的结论，因为被检查的老鼠的数量不足以进行统计分析。此外，我们推测，大鼠的物种及其年龄与辐射暴露后引起甲状腺肿瘤的敏感性有关。在未来，我们将进一步研究甲状腺癌与碘-131暴露之间的关系。

After Chernobyl disaster at 1986, the number of childhood thyroid cancer increased there. We were joining the Chernobyl Sasakawa Health and Medical Cooperation Project form 1991 to 1996. We screened more than 13000 children during 5 years. The incidence of childhood thyroid cancer is 100 times higher than Japan. Unfortunately, we did not have the data about the direct thyroid dosimetory of these patients at the time of the accident. The direct relationship between radiation and thyroid cancer is still uncertain. On the other hand, previous reports showed no increase of thyroid cancer among patients who were diagnosed or treated using Iodine-131. To elucidate whether radio-iodine intake cause thyroid cancer, we have tried to make animal model that is internally exposed by Iodine-131. Iodine-131(0, 0.2, 0.6, 1Mbq) was peritoneally injected to rats that previously took low iodine diets (n=10/each group). One, two, six or twelve months after radiation exposure, rats were sacrificed and analyzed pathophigiologically. We observed no increase of thyroid tumor among exposed rats. The result does not lead to any concrete conclusions because the number of examined rats is not good enough to statistically analyze. Furthermore, we speculate that rat spicies and their ages relate to sensitivity to cause thyroid tumors following radiation exposure. In future, we win further examine to answer the relationship between thyroid cancer and Iodine-131 exposure.