FDG PET/CT imaging in recurrent papillary thyroid cancer: does BRAF mutation status matter?

Papillary thyroid carcinoma (PTC) with a BRAFV600E mutation is linked to more aggressive tumor characteristics, as well as a higher likelihood of recurrence and disease-specific mortality. This study aimed to investigate the association between BRAFV600E mutation status in patients with recurrent PTC post radioiodine (RAI) therapy and its relationship with clinicopathological characteristics and [¹⁸F]FDG-uptake patterns on PET/CT.

The multi-step selection process resulted in a final cohort of 38 patients out of 851 patients with thyroid carcinoma. The final cohort had confirmed papillary thyroid carcinoma, underwent thyroidectomy with subsequent RAI treatment, documented BRAFV600E status and elevated thyroglobulin (Tg) levels, and a [¹⁸F]FDG-PET/CT scan post-biopsy. Collected clinicopathological data encompassed among others tumor size and number of metastases. Furthermore, the lesions' SUVmax, peak, mean, MTV, and TLG were assessed, and associated with the respective BRAF-Status and the clinicopathological data.

The statistical analyses showed a significant association between SUVmax, SUVpeak, SUVmean, and BRAFV600E mutation status, with P=0.009, P=0.0088, P=0.0092, respectively. There was also an independent correlation between tumor size and SUVmax. No significant difference in tumor size was observed between the BRAF+ and BRAF- groups. There was no significant association between TLG, MTV, Tg levels with SUVs.

The BRAFV600E mutation and larger tumor size are linked to increased maximum, mean, and peak FDG uptake values on [¹⁸F]FDG-PET/CT in patients with recurrent PTC. These findings improve understanding of mutation-associated metabolic behavior in recurrent PTC; however, they do not support changes in clinical management or risk stratification based solely on FDG PET/CT metrics or BRAFV600E status. Further research should investigate the potential of [¹⁸F]FDG-PET/CT metrics as biomarkers for guiding individualized treatment strategies in BRAFV600E-positive PTC.