BRAF Mutation Testing of Thyroid Fine-Needle Aspiration Biopsy Specimens for Preoperative Risk Stratification in Papillary Thyroid Cancer

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Abstract
This study investigated the utility of BRAF mutation testing of thyroid fine-needle aspiration biopsy (FNAB) specimens for preoperative risk stratification in papillary thyroid cancer (PTC). We assessed the T1799A BRAF mutation status in thyroid FNAB specimens obtained from 190 patients before thyroidectomy for PTC and its association with clinicopathologic characteristics of the tumor revealed postoperatively. We observed a significant association of BRAF mutation in preoperative FNAB specimens with poorer clinicopathologic outcomes of PTC. In comparison with the wild-type allele, BRAF mutation strongly predicted extrathyroidal extension (23% v 11%; P = .039), thyroid capsular invasion (29% v 16%; P = .045), and lymph node metastasis (38% v 18%; P = .002). During a median follow-up of 3 years (range, 0.6 to 10 years), PTC persistence/recurrence was seen in 36% of BRAF mutation–positive patients versus 12% of BRAF mutation–negative patients, with an odds ratio of 4.16 (95% CI, 1.70 to 10.17; P = .002). The positive and negative predictive values for preoperative FNAB-detected BRAF mutation to predict PTC persistence/recurrence were 36% and 88% for overall PTC and 34% and 92% for conventional PTC, respectively. Preoperative BRAF mutation testing of FNAB specimens provides a novel tool to preoperatively identify PTC patients at higher risk for extensive disease (extrathyroidal extension and lymph node metastases) and those who are more likely to manifest disease persistence/recurrence. BRAF mutation, as a powerful risk prognostic marker, may therefore be useful in appropriately tailoring the initial surgical extent for patients with PTC.