Clinical significance of the BRAF V600E mutation in multifocal papillary thyroid carcinoma in Korea.

Abstract

We examined the frequency of the BRAF(V600E) mutation and compared the clinicopathologic features based on the BRAF(V600E) mutation status in multifocal papillary thyroid carcinoma (PTC). A total 85 patients who were diagnosed with multifocal PTC were enrolled. We confirmed the status of the BRAF(V600E) mutation in each tumor focus by the real-time polymerase chain reaction technique. Among the 85 patients, 49 (57.6%), 34 (40.0%), and 2 (2.4%) patients were determined to have all BRAF(V600E)-positive, mixed BRAF(V600E), and all BRAF(V600E)-negative in their tumor foci, respectively. When we compared clinicopathologic features according to the BRAF(V600E) mutation status of the dominant tumor, the BRAF(V600E) -positive group (n = 70) showed more extrathyroidal invasion in the dominant tumor (32.9% vs 6.7%, P = .041) and more lymph node metastasis (67.2% vs 40.0%, P = .049) than the BRAF(V600E) -negative group (n = 15). Considering all tumor foci, the all BRAF(V600E) mutation group exhibited a younger population (P = .039), showed increased extrathyroidal invasion (38.8% vs 14.7%, P = .017) and lymph node metastasis (71.4% vs 48.4%, P = .038), and received more radioactive iodine therapy (79.2% vs 52.9%, P = .012) than the mixed BRAF(V600E) mutation group. A larger tumor size and heavier preoperative body weight was positively correlated with the relative expression of BRAF(V600E) mutation calculated by 2(-△△Ct) method. Most of the Korean patients with multifocal PTC had the BRAF(V600E) mutation in one or more tumor foci, and all BRAF(V600E)-positive multifocal PTC showed more aggressive features.