Effects of BRAF^(V600E) Mutation on Na^+/I^- Symporter Expression in Papillary Thyroid Carcinoma

Radioiodine ablation（RIA） therapy is one of the most important treatments for papillary thyroid carcinoma（PTC）, but some patients who received 131 I have radioiodine-refractory disease caused by the decreased expression of the Na^＋/I^- symporter（NIS）. BRAF^V600E mutation is one possible risk factor that can disturb the NIS expression, but the roles are unclear in clinical practice. This research discussed the association of BRAF^V600E mutation and NIS expression in PTC tissue and the clinical implications in RIA therapy. 134 PTC samples were collected between June 2013 and June 2014 from Tongji Hospital affiliated to Tongji Medical College, and their clinical characteristics were analyzed. RT-PCR was used to detect the BRAF^V600E mutation from formalin-fixed paraffin-embedded samples, and immunohistochemistry was applied to detect the NIS expression. IPP software was used to calculate the relative expression quantity of NIS. We found that there was no significant correlation between the absorbance（A） values of NIS and clinicopathologic features in these cases, even thyroid stimulating hormone. BRAF^V600E mutation showed inhibitory effect on the NIS expression without statistically significant difference in all PTC cases（β=–0.0195, P=0.085）, but in the subgroup without hashimoto＇s thyroiditis（HT）, BRAF^V600E mutation could significantly inhibit the NIS expression（β=–0.0257, P=0.046）. The results indicate that BRAF^V600E mutation is correlated with a lower expression of NIS in PTCs without HT, suggesting the radioiodine-refractory effects during RIA therapy in these patients.

Postoperative Stimulated Thyroglobulin Level and Recurrence Risk Stratification in Differentiated Thyroid Cancer

Background： Postoperative preablative stimulated thyroglobulin （ps-Tg） has been evaluated in predicting prognosis and success of ablation regarding differentiated thyroid cancer （DTC）; however, its relationship with recurrence risk and radioiodine decision-making remains uncertain, especially in Chinese DTC patients. We aimed to evaluate the association between ps-Tg and recurrence risk stratification in DTC, to provide incremental values for ps-Tg in postoperative assessment and radioiodine management. Methods： Seven hundred and seven patients with DTC were included; low-risk （L; n = 90）, intermediate-risk （I; n = 283）, and high-risk （H; n = 334, 117 with distant metastasis [M 1 ]） patients were divided according to recurrence risk stratification. The M 1 group was further analyzed regarding evidence of metastasis. Cut-off values of ps-Tg were obtained using receiver operating characteristic analysis. Results： Patients with more advanced disease at initial risk stratification were more likely to have higher ps-Tg levels （I vs. L： P 〈 0.05; H vs. 1： P 〈 0.001; H vs. L： P 〈 0.001）. The corresponding cut-off value of ps-Tg for distinguishing sensitivity and specificity in each of the two groups was 2.95 ng/ml （1 vs. L： 61.5%, 63.3%）, 29.5 ng/ml （H vs, I： 41.9%, 92.6%）, 47.1 ng/ml （M1 vs. M0 in the H group： 79.5%, 88.9%） and 47.1 ng/ml （MI vs. M0 in all patients： 79.5%, 93.7%）. With the cut-offvalue at 47.1 ng/ml, ps-Tg was the only factor that could be used to identify distant metastases, and consequently if measured before radioiodine therapy would prevent 10.26% of patients with M1 from undertreatment, Conclusions： Ps-Tg, as an ongoing reassessment marker, favors differential recurrence risk grading and provides incremental values for radioiodine treatment decision-making.