Real-life use of BRAF-V600E mutation analysis in thyroid nodule fine needle aspiration: consequences on clinical decision-making

Purpose This study aimed to evaluate the real-life use of BRAF-V600E mutation analysis in washout liquid from thyroid nodule fine needle aspiration (FNA), and the consequences of genetic result on clinical decision-making. Methods We retrospectively considered subjects tested for BRAF-V600E among those attending the Endocrinology Unit of Modena for FNA between 2014 and 2018. Washing fluid was collected together with cytological sample and stored at -20 degrees C. If the clinician deemed it necessary, the sample was thawed, DNA extracted, and genetic test performed by high-resolution melting technique. We collected data on cytology according to the Italian Consensus for the cytological classification of thyroid nodules, type of surgery (when performed), histology, and adverse events. Results Out of 7112 subjects submitted to FNA, BRAF analysis was requested for 683 (9.6%). Overall, 896 nodules were analyzed: 74% were indeterminate at cytology, mainly TIR3A (low risk). Twenty-two nodules were mutant (BRAF+). Only 2% of indeterminate, mainly TIR3B, were BRAF+. Based on final histological diagnosis, BRAF test had high specificity (100%) but poor sensitivity (21%), also in indeterminate nodules. Mutant subjects underwent more extensive surgery compared to wild type (p = 0.000), with frequent prophylactic central lymph node dissection. One third had local metastases. Higher prevalence of hypoparathyroidism was found in BRAF+ compared to wild type (p = 0.018). Conclusions The analysis of BRAF-V600E outside of gene panels has low sensitivity, especially in indeterminate nodules, and a positive result could lead to more extensive surgery with greater risk of hypoparathyroidism and questionable clinical utility.