BRAF mutation in papillary thyroid carcinoma in a Japanese population: its lack of correlation with high-risk clinicopathological features and disease-free survival of patients.

Recent studies have demonstrated that BRAF(V600E) mutation is a common event in papillary thyroid carcinoma and a majority of these lesions have shown a direct relationship between BRAF(V600E) mutation and aggressive characteristics, including a worse patient prognosis. However, there are no studies from Japan regarding this issue in a large series with adequate postoperative follow-up periods. We investigated BRAF(V600E) mutation in 631 patients with papillary carcinoma having median follow-up periods of 83 months. The prevalence of BRAF(V600E) mutation was 38.4%, and the rate was higher in carcinoma larger than 1.0 cm but did not successively increase with tumor size. Furthermore, the prevalence did not significantly increase in cases demonstrating high-risk biological features such as clinically apparent lymph node metastasis, massive extrathyroid extension, advanced age, distant metastasis at surgery, and advanced Stage. The disease-free survival of patients with BRAF(V600E) mutation did not differ from that of those without BRAF(V600E) mutation. These findings indicate that, although BRAF(V600E) mutation may play some roles in local carcinoma development, there is no evidence that BRAF(V600E) mutation significantly reflects the aggressive characteristics and poor prognosis of patients with papillary carcinoma in Japan.