Poorer prognosis and higher prevalence of BRAF (V600E) mutation in synchronous bilateral papillary thyroid carcinoma.

Overview

abstract

BACKGROUND: The clinical significance of synchronous bilateral papillary thyroid carcinoma (SBiPTC) has not been fully defined, and the prevalence of BRAF (V600E) mutation in SBiPTC remains unknown. The purpose of this study is to compare the clinical outcomes and BRAF (V600E) mutation incidence of SBiPTC patients with those of unilateral papillary thyroid carcinoma (UiPTC) patients. METHODS: From 1997 to 2008, a total of 903 patients with papillary thyroid cancer were treated at a single institution. Of 891 studied patients, 177 (19.9%) had SBiPTC and 714 had UiPTC. SBiPTC was defined as cancer diagnosed in both thyroid lobes at the same time or within a period of 3 months. The mean follow-up time was 6 years, ranging from 2.5 to 13.5 years. Rates of disease-free survival (DFS) and overall survival (OS) were calculated and compared. BRAF (V600E) mutation was determined by polymerase chain reaction (PCR) amplification and DNA sequencing. RESULTS: Compared with UiPTC patients, patients with SBiPTC were more likely to have larger tumor size, extrathyroidal invasion, lymph node metastasis, and more advanced stage. The 5-year DFS rate was 86.0% for SBiPTC patients and 94.0% for UiPTC patients (p = 0.013). The prevalence of BRAF (V600E) mutation in the SBiPTC group was significantly higher than that in the UiPTC group (65.7% vs. 50.4%; p = 0.038). CONCLUSIONS: Patients with SBiPTC present with more advanced tumor stage and have shorter disease-free survival than UiPTC patients. Poorer outcomes of these patients may be at least partially explained by the high incidence of BRAF (V600E) mutation.