Collins Barbara J, Schneider Arthur B, Prinz Richard A, Xu Xiulong
Section of Endocrinology and Metabolism, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.
Thyroid. 2006 Jan;16(1):61-6. doi: 10.1089/thy.2006.16.61.
Radiation exposure at a young age is the only environmental factor known to cause thyroid cancer, predominantly of the papillary type. We have previously reported a high percentage (86.7%) of RET-positive papillary thyroid cancers in a cohort of individuals exposed to external radiation of the head and neck area before the age of 16. Recently, we and others have reported that point mutations of the BRAF gene occur with high frequency among sporadic adult papillary thyroid carcinomas, but occur at a much lower frequency in the population exposed after the Chernobyl accident. We here report that there is a similar low frequency of BRAF mutations among our cohort of those exposed to external beam radiation as children who later developed papillary thyroid cancer as adults. Samples were analyzed by mutation allele-specific amplification (MASA) for the most common T1799A mutation in exon 15 that converts amino acid 600 from valine to glutamate. In 23 cases, only 1 sample was positive. These results are further evidence that BRAF mutations, while common in sporadic adult papillary thyroid cancers, are rare events in cancers seen in subjects exposed to radiation as children.
幼年时期的辐射暴露是已知的唯一会引发甲状腺癌的环境因素，主要引发乳头状甲状腺癌。我们之前曾报道，在一组16岁之前接受过头颈部区域外部辐射的人群中，RET阳性乳头状甲状腺癌的比例很高（86.7%）。最近，我们和其他人报道，BRAF基因的点突变在散发性成人乳头状甲状腺癌中高频出现，但在切尔诺贝利事故后受辐射人群中出现频率要低得多。我们在此报告，在我们那组幼年时接受过外照射放疗、后来成年后患乳头状甲状腺癌的人群中，BRAF突变的频率同样很低。通过突变等位基因特异性扩增（MASA）分析样本，检测外显子15中最常见的将第600位氨基酸由缬氨酸转变为谷氨酸的T1799A突变。在23个病例中，只有1个样本呈阳性。这些结果进一步证明，BRAF突变虽然在散发性成人乳头状甲状腺癌中常见，但在幼年受辐射人群所患的癌症中却是罕见事件。
