Molecular epidemiology of radiation induced thyroid cancer

据报告，在儿童时期接触1986年切尔诺贝利核事故的高水平放射性粉尘的人中，甲状腺癌发病率大幅增加。切尔诺贝利组织银行(CTB)是一个得到国际支持的项目，确保材料(冰冻组织、固定组织切片、提取的DNA/RNA和血液样本)可用于适当的研究。到目前为止，已有超过2500例病例登记在案，CTB掌握着爆炸发生时来自19岁以下患者的280多个甲状腺肿瘤的DNA和RNA。尽管在切尔诺贝利周围暴露于放射性粉尘后，超过95%的癌症被归类为乳头状癌，但它们的形态各不相同，从坚固的未成熟表型到以乳头或滤泡结构为主的高分化肿瘤。一些早期关于切尔诺贝利周围甲状腺癌的报道表明，实体形态、侵袭性、…RET/PTC3重排频率较高或明显较高提示放射源性肿瘤。然而，最近的研究表明，乳头状癌的形态模式随着潜伏期的增加而改变。我们发现，与潜伏期较长的肿瘤相比，潜伏期短的肿瘤与坚实的形态和明显更具侵袭性的扩散有关。相反，分化的类型与暴露时的年龄有关。许多报道表明，RET/PTC3重排与短潜伏期肿瘤的固体形态有关，而分化较好的乳头状癌更常见的是RET/PTC1重排。在切尔诺贝利事故后的甲状腺癌中，BRAF突变的频率很低，与在其他儿童甲状腺乳头状癌研究中观察到的相似，这可能与患者确诊时的年龄有关。最近的研究显示，来自乌克兰和俄罗斯的未暴露组的肿瘤在形态上与同一地区暴露的肿瘤基本相同。来自日本儿童的肿瘤与切尔诺贝利周围的肿瘤有显著差异，无论暴露或未暴露，表现为明显更多的分化，更多的乳头分化。一种值得认真考虑的可能性是饮食中的碘含量。较少

A large increase in thyroid carcinoma incidence among those exposed as children to the high levels of fallout from the nuclear accident at Chernobyl in 1986 has been reported. The Chernobyl Tissue Bank (CTB) is an internationally supported project and ensures that materials (frozen tissue, fixed tissue sections, extracted DNA/RNA and blood samples) are available for appropriate research studies. Up to date more over 2,500 cases have been registered, and the CTB holds DNA and RNA from more than 280 thyroid tumors from the patients younger than 19 at the time of the explosion.Although over 95% of the cancers are classified as papillary carcinomas in the population around Chernobyl following exposure to fallout, they vary in their morphology, ranging from a solid immature phenotype, to well differentiated tumors dominated by either papillary or follicular architecture. Some of the early reports on the thyroid carcinomas around Chernobyl suggested that the solid morphology, aggressiveness, … More and the apparently high frequency of RET/PTC3 rearrangements were indicative of radiogenic tumors. However, recent studies have shown that the morphological pattern of papillary carcinomas is changing with increasing latency. We showed that short latency is associated with solid morphology and significantly more invasive spread when compared to tumors with a longer latent period. In contrast, the type of differentiation is associated with age at exposure. Many reports have suggested that RET/PTC3 rearrangements are associated with the solid morphology seen in short latency tumors, while well diffrentiated papillary carcinomas more often show RET/PTC1 rearrangements. The frequency of BRAF mutation is low in post Chernobyl thyroid cancer and is similar to that observed in other studies of childhood thyroid papillary carcinoma, and this may be related to the age of the patient at diagnosis. More recent study revealed that the unexposed group of tumors from Ukraine and Russia were essentially identical morphologically to the exposed tumors from the same area. The tumors from Japanese children were significantly different from the tumors from around Chernobyl, whether exposed or unexposed, showing significantly more differentiation, more papillary differentiation. One possibility deserving serious consideration is the iodine content of the diet. Less