BRAF mutation testing of thyroid fine-needle aspiration biopsy specimens for preoperative risk stratification in papillary thyroid cancer

Abstract

Purpose: 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).

Patients and methods: 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.

Results: 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.

Conclusion: 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.

Fig 1.

Kaplan-Meier estimate of papillary thyroid cancer disease-free probability in patients with or without BRAF mutation. Short vertical lines indicate censored observations (months of follow-up for those who have not had recurrence/persistence; standard log-rank test; χ² = 9.2; P = .002).