[430] Predictive Value of Pre-Operative Thyroid FNA BRAF Mutation Testing for Risk of Lymph Node Thyroid Carcinoma Metastases: A Single Institution Experience of 498 Cases

Berrin Ustun, Adebowale Adeniran, Guoping Cai, Sanziana Roman, Julie Ann Sosa, Elizabeth Holt, David C Chhieng, Constantine GA Theoharis. Yale University School of Medicine, New Haven, CT

Background: Thyroid fine needle aspiration (FNA) is standard in the evaluation of thyroid nodules for carcinoma. Recently, the utilization of reflex BRAF mutation adjunct testing has afforded cytology a diagnostic tool with prognostic implications. BRAF positivity is associated with compromised prognostic findings including: lymph node positivity, recurrence/reoperation risk, and radioiodine resistance. In this study we evaluate the predictive value of pre-operative thyroid FNA BRAF mutation testing in regard to finding cervical lymph node metastases.
Design: We reviewed 498 consecutive thyroid FNAs performed on 447 patients between 2009 and 2012, the period in which reflex BRAF mutation testing was available at our institution. Average patient age was 53 years, with men and women represented equally. Reflex BRAF testing was initiated on diagnoses of atypia (of undetermined significance), and those suspicious/definitive for malignancy.
Results: The results showed: 173/498 (35%) cases where BRAF was mutated, 294/498 (59%) where BRAF was wild type (WT), and 31/498 (6%) where BRAF was inconclusive. 283 of 498 cases had a thyroidectomy with or without a lymphadenectomy (LN); representing 118 BRAF mutated, 147 BRAF WT, 18 BRAF inconclusive cases. 77 of 283 cases had positive lymph nodes as follows:

Lymph Node Positivity as Predicted by BRAF
 Node Status   
BRAF statusCases (N)Central Nodes, Level VI (+)Lateral Nodes, Levels II-V (+)Total Nodes (+)
BRAF mutated118261339
BRAF WT147171128
BRAF188210
Total283512677
LN: Lymphadenectomy

Sensitivity was 58%; specificity was 100%, while positive and negative predictive values were l00% and 88%, respectively. The Likelihood Ratio was 35.4.
Conclusions: The utilization of reflex BRAF molecular testing on thyroid FNA specimens has prognostic utility in predicting lymph node metastases. Based on these findings, prophylactic central lymphadenectomy may be considered at the time of thyroidectomy in patients with BRAF mutations diagnosed on pre-op FNA.
Category: Cytopathology

Tuesday, March 5, 2013 2:00 PM

Proffered Papers: Section C, Tuesday Afternoon

 

Close Window