Objective: To examine the prevalence of BRAF mutation among thyroid cancer histologic subtypes and determine the association of BRAF mutation with indicators of poor prognosis for papillary thyroid cancer and patient outcome.
Summary background data: The appropriate extent of surgical treatment, adjuvant therapy and follow-up monitoring for thyroid cancer remains controversial. Advances in the molecular biology of thyroid cancer have helped to identify candidate markers of disease aggressiveness. A commonly found genetic alternation is a point mutation in the BRAF oncogene (BRAF V600E), which is primarily found in papillary thyroid cancer and is associated with more aggressive disease.
Methods: BRAF V600E mutation status was determined in 347 tumor samples from 314 patients with thyroid cancer (245 with conventional papillary thyroid cancer, 73 with follicular thyroid cancer, and 29 with the follicular variant of papillary thyroid cancer). Univariate and multivariate analyses were performed to determine the association of BRAF V600E with clinicopathologic factors and patient outcome.
Results: : The prevalence of BRAF V600E mutation was higher in conventional papillary thyroid cancer (51.0%) than in follicular variant of papillary thyroid cancer (24.1%) and follicular thyroid cancer (1.4%) (P < 0.0001). In patients with conventional papillary thyroid cancer, BRAF V600E mutation was associated with older age (P = 0.0381), lymph node metastasis (P = 0.0323), distant metastasis (P = 0.045), higher TNM stage (I and II vs. III and IV, P = 0.0389), and recurrent and persistent disease (P = 0.009) with a median follow-up time of 6.0 years. Multivariate analysis showed that BRAF V600E mutation [OR (95% CI) = 4.2 (1.2-14.6)] and lymph node metastasis [OR (95% CI) = 7.75 (2.1-28.5)] were independently associated with recurrent and persistent disease in patients with conventional papillary thyroid cancer.
Conclusions: BRAF V600E mutation is primarily present in conventional papillary thyroid cancer. It is associated with an aggressive tumor phenotype and higher risk of recurrent and persistent disease in patients with conventional papillary thyroid cancer. Testing for this mutation may be useful for selecting initial therapy and for follow-up monitoring.