Lymphatic mapping establishes the role of BRAF gene mutation in papillary thyroid carcinoma

OBJECTIVE: To define the role of BRAF gene mutation in the progression of papillary thyroid carcinoma. SUMMARY BACKGROUND DATA: BRAF gene mutation is frequently detected in papillary thyroid carcinoma. Its role in pathogenesis or progression is under investigation. METHODS: Patients who underwent thyroidectomy and sentinel lymph node biopsy for papillary thyroid cancer were accrued. BRAF mutation was assessed in primary tumors and matched sentinel lymph nodes by a quantitative real-time PCR assay. RESULTS: Tissue specimens from 103 consecutive patients were evaluated. BRAF mutation of the primary tumor was detected in 34 (33%) patients. In 26 of 34 (76%) patients with BRAF mutation, concomitant lymph node metastasis was detected. On the contrary, in 69 patients with BRAF mutation-negative primary tumors, only 12 (17%) patients had lymph node metastasis (χ, P < 0.0001). BRAF mutation was detected in 20 of 26 (77%) lymph node metastases matched to BRAF mutation-positive primary tumors; it was not detected in lymph node metastases matched to BRAF mutation-negative primary tumors. Univariate analysis identified age, stage, tumor size, and BRAF mutation as prognostic factors for lymph node metastasis. In multivariate analysis, only BRAF mutation remained a significant prognostic factor for lymph node metastasis (odds ratio = 10.8, 95% confidence interval, 3.5-34.0, P < 0.0001). CONCLUSIONS: BRAF mutation may be a key genetic factor for the metastatic progression of papillary thyroid carcinoma. The study demonstrates that this gene mutation is a significant risk factor for locoregional lymph node metastasis and has potential utility as a surrogate marker.