Clinical significance of the BRAFV600E mutation in multifocal papillary thyroid carcinoma in Korea

BackgroundWe examined the frequency of the BRAFV600E mutation and compared the clinicopathologic features based on the BRAFV600E mutation status in multifocal papillary thyroid carcinoma (PTC).MethodsA total 85 patients who were diagnosed with multifocal PTC were enrolled. We confirmed the status of the BRAFV600E mutation in each tumor focus by the real-time polymerase chain reaction technique.ResultsAmong the 85 patients, 49 (57.6%), 34 (40.0%), and 2 (2.4%) patients were determined to have all BRAFV600E-positive, mixed BRAFV600E, and all BRAFV600E-negative in their tumor foci, respectively. When we compared clinicopathologic features according to the BRAFV600E mutation status of the dominant tumor, the BRAFV600E -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 BRAFV600E -negative group (n = 15). Considering all tumor foci, the all BRAFV600E 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 BRAFV600E mutation group. A larger tumor size and heavier preoperative body weight was positively correlated with the relative expression of BRAFV600E mutation calculated by 2−△△Ct method.ConclusionMost of the Korean patients with multifocal PTC had the BRAFV600E mutation in one or more tumor foci, and all BRAFV600E-positive multifocal PTC showed more aggressive features.