Genetic alterations of differentiated thyroid carcinoma in iodine‐rich and iodine‐deficient countries

Abstract

BRAF V600E mutation, RET rearrangements, and RAS mutations are the common genetic alterations in differentiated thyroid carcinomas derived from follicular thyroid cells. However, the relationship between these alterations and iodine intake is still controversial. To clarify the influence of iodine intake on the occurrence of differentiated thyroid carcinomas, we performed molecular analyses for two differentiated carcinomas, papillary thyroid carcinomas (PTCs) and follicular thyroid carcinomas (FTCs), from an iodine‐rich country (Japan) and an iodine‐deficient country (Vietnam). We examined 120 PTCs (67 Japanese and 53 Vietnamese) and 74 FTCs (51 Japanese and 23 Vietnamese). We carried out allele‐specific polymerase chain reaction (AS‐PCR) for BRAF V600E, PCR and direct sequencing for RAS mutations (codon 12, 13, and 61 in NRAS,HRAS, and KRAS), and RT‐PCR for RET/PTC1 and RET/PTC3. BRAF V600E was present in 55/67 (82.1%) Japanese PTCs and 44/53 (83%) Vietnamese PTCs. RET/PTC1 was identified in only one PTC from each country, and no samples had RET/PTC3. NRAS mutation was found in 17/51 (33.3%) Japanese FTCs and 4/23 (17.4%) Vietnamese FTCs. NRAS mutation was cited in codon 61 (20 cases) and codon 12 (one case). None of FTCs had KRAS or HRAS mutations. There were no significant differences in the prevalence of BRAF V600E,RET/PTC, or RAS mutations between the two countries. Our study showed no differences in genetic alterations of thyroid cancers from iodine‐rich and iodine‐deficient countries, possibly suggesting that iodine intake might not affect the genetic alterations of differentiated thyroid cancer.

TERT promoter mutations and Ki-67 labeling index as a prognostic marker of papillary thyroid carcinomas: combination of two independent factors

“…The prevalence of the BRAF V600E mutation in PTCs in East Asian countries including Japan is high. The prevalence of the BRAF V600E mutation was reported to be dependent on the amount of iodine intake 29 ; however, very recently it has been demonstrated that there was no difference in the BRAF V600E prevalence between Japan, an iodine-rich country, and Vietnam, an iodine-deficient country 30 . Interestingly, in the meta-analysis by Kim et al .…”

Prevalence ofBRAFV600EMutation in Follicular Variant of Papillary Thyroid Carcinoma and Non-Invasive Follicular Tumor with Papillary-Like Nuclear Features (NIFTP) in aBRAFV600EPrevalent Area

“… 31 In contrast, a very recent study showed no differences in genetic alterations of PTC from iodine-rich (Japan) and iodine-deficient (Vietnam) countries. 32 Thus, there is still no consensus regarding the association of iodine intake and the high prevalence of the BRAF V600E mutation in patients with PTC in iodine sufficient areas. Therefore, these associations should be further elucidated in future studies.…”

The Mitochondrial DNA Control Region Might Have Useful Diagnostic and Prognostic Biomarkers for Thyroid Tumors

“…In addition to the benign nodules, 48 PTC samples and surrounding tissues, which were obtained from pathology archive materials, were also taken into this study. Their histopathological evaluations were performed according to WHO criteria from 2004 [27]. The PTC samples were divided into two groups based on tumor diameter.…”