BRAF^V600E mutation is the most common genetic alteration in papillary thyroid cancer (PTC) and has been associated with poor prognostic factors. The purpose of the present study is to investigate the frequency of the BRAF mutation in PTC with and without benign thyroid nodules (BN).

98 DNA samples were extracted from frozen tissues of 51 PTC and 47 BN specimens of 70 patients and were divided into four group: PTC with BN, PTC alone, BN with PTC and BN alone group. We investigated the BRAF mutation by sequencing and clinicopathologic characteristics.

Total positive rate of BRAF mutation was 23.5% in the two PTC groups. That rate of the PTC with BN group was 10.7% and the PTC alone group was 39.1%. Positive rate in the PTC with BN group was lesser than the PTC alone group and had statistically difference (P=0.02). The positive rate of BRAF mutation was 7.1% in the BN with PTC group and 5.3% in the BN alone group. Positive rate in these two group was not statistically different (P=0.80).

The frequency of BRAF mutation in PTC with concurrent BN was lower than in PTC alone. This result suggests that the effect of BRAF mutation is lesser associated with PTCs with BN than PTC alone group.