BRAF(V600E) Mutation is a Strong Preoperative Indicator for Predicting Malignancy in Thyroid Nodule Patients with Atypia of Undetermined Significance Identified by Fine Needle Aspiration / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: This study aimed to identify a reliable preoperative predictive factor for the development of thyroid cancer in patients with atypia of undetermined significance (AUS) identified by fine needle aspiration biopsy (FNAB). SUBJECTS AND METHOD: This was a retrospective cohort study. Two hundred and ninety-nine patients diagnosed with AUS by preoperative FNAB who underwent curative thyroid surgery at our institution between September 2005 and February 2014 were analyzed. Clinical, radiological and molecular features were investigated as preoperative predictors for postoperative permanent malignant pathology. RESULTS: The final pathologic results revealed 36 benign tumors including nodular hyperplasia, follicular adenoma, adenomatous goiter, nontoxic goiter, and lymphocytic thyroiditis, as well as 263 malignant tumors including 1 follicular carcinoma and 1 invasive follicular carcinoma; the rest were papillary thyroid carcinomas. The malignancy rate was 87.9%. The following were identified as risk factors for malignancy by univariate analysis: BRAFV600E gene mutation, specific ultrasonographic findings including smaller nodule size, low echogenicity of the nodule, and irregular or spiculated margin (p < 0.05). Multivariate analysis revealed that only BRAFV600E mutation was a statistically significant risk factor for malignancy (p < 0.05). When BRAFV600E mutation was positive, 98.5% of enrolled patients developed malignant tumors. In addition, the diagnostic rate of malignancy in these cases was approximately 16-fold higher than BRAF-negative cases. CONCLUSION: Patients with AUS thyroid nodules should undergo BRAFV600E gene mutation analysis to improve diagnostic accuracy and if the mutation is confirmed, surgery is recommended due to the high risk of malignancy.