Association Between 18F-FDG Avidity and the BRAF Mutation in Papillary Thyroid Carcinoma

Abstract

Purpose The BRAF mutation, a potential prognostic factor in papillary thyroid carcinoma (PTC), is associated with a high expression of the glucose transporter gene. We investigated which clinicopathologic factors, including BRAF mutation status, influence 18 F-fluoro-2-deoxyglucose ( 18 F-FDG) avidity. Methods We retrospectively reviewed 55 patients who underwent BRAF analysis from biopsy-confirmed PTC and 18 F-FDG positron emission tomography/computed tomography within 6 months before undergoing thyroid surgery from September 2008 to August 2014. Tumors were considered to be 18 F-FDG avid if the uptake was greater than that of the liver. 18 F-FDG uptake of PTCs was also analyzed semiquantitatively using SUV max . The association between 18 F-FDG avidity and clinicopathologic variables (age, tumor size, perithyroidal extension, cervical lymph node status, and BRAF mutation status) was investigated. Results Twenty-nine (52.7 %) of 55 patients had 18 F-FDGavid PTCs. PTCs with the BRAF mutation showed higher 18 F-FDG avidity (24/38, 63.2 %) than those without (5/17, 29.4 %). The BRAF mutation (p=0.025) and tumor size (p= 0.003) were significantly associated with 18 F-FDG avidity in univariate analysis, and the BRAF mutation status remained significant after adjusting for tumor size in multivariate analysis (p=0.015). In the subgroup of tumor size≥1 cm, the BRAF mutation was the only factor significantly associated with 18 F-FDG avidity (p=0.021). The mean SUV max of PTCs with the BRAF mutation was significantly higher than that of those without (4.89±6.12 vs. 1.96±1.10, p=0.039). Conclusions The BRAF mutation must be one of the most important factors influencing 18 F-FDG avidity in PTCs, especially in those with a tumor size≥1 cm.

Clinicopathological characteristics including BRAF V600E mutation status and PET/CT findings in papillary thyroid carcinoma

“…There was a difference only in tumour size between the groups. This finding differs from those of previous studies addressing the clinicopathological characteristics according to tumour FDG avidity . Kim et al .…”

“…We conducted an observational study using retrospectively collected data from patients with PTC at a single centre to investigate the clinical value of preoperative PET/CT as a candidate predictor of local tumour invasiveness. There has been controversy regarding the association between FDG uptake of the primary tumour on PET/CT and clinicopathological features related to tumour aggressiveness . Several investigators have shown that a larger tumour size, the presence of extrathyroid extension and lymph node metastasis are more likely to be associated with PTC FDG positivity .…”

“…Some data on the association between the PTC SUVmax and BRAF V600E mutation status have been published with regard to FDG PET/CT findings . Lee at al .…”

“…Recently, some studies have shown that the level of FDG uptake is significantly associated with clinicopathological features in patients with PTC. In particular, the BRAF V600E mutation status is an emerging factor associated with FDG uptake on PET/CT in patients with PTC . However, a definite relationship between clinicopathological characteristics and the prognostic relevance of FDG uptake remains to be undetermined.…”

“…In particular, the BRAF V600E mutation status is an emerging factor associated with FDG uptake on PET/CT in patients with PTC. 11,12 However, a definite relationship between clinicopathological characteristics and the prognostic relevance of FDG uptake remains to be undetermined. An understanding of the clinicopathological characteristics that may influence FDG uptake is necessary to evaluate the prognostic impact of preoperative PET/CT findings in patients with PTC.…”