Objective: To investigate the relationship of BRAF  mutation with the outcome of the first postoperative ¹³¹I treatment and malignant biological characteristics in papillary thyroid carcinoma (PTC).
Methods: Thirty-three patients with PTC who underwent their first ¹³¹I treatment after total thyroidectomy were enrolled in this study. BRAF mutation in postoperative tumor tissue and circulating tumor DNA (ctDNA) in peripheral blood at the time of ¹³¹I treatment were detected. According to the status of BRAF  mutation, all patients were divided into 2 groups in each category of tumor tissues and ctDNA, respectively: 1) BRAF  mutation, 2) BRAF  wild-type. The Fisher’s exact test was performed to analyze the relationship of BRAF  mutation in either tumor tissue or ctDNA with the outcome of the first ¹³¹I treatment and malignant characteristics of PTC.
Results: BRAF  mutation was detected in tumor tissues in 25 patients (25/33,75.8%), and all the patients had single mutation site. In ctDNA, BRAF  mutation was detected in 5 patients (5/33, 15.2%), and all the patients had single mutation site. In both tumor tissues and ctDNA, BRAF  mutation showed no relationship with the outcome of first ¹³¹I treatment and the malignant biological characteristics (P> 0.05).
Conclusion: The value of BRAF  mutation alone might be limited in predicting therapeutic outcome of the first ¹³¹I treatment in PTC. No definitive relevance was found between BRAF  mutation and malignant biological features in PTC.
Keywords: gene mutation, BRAF , radiotherapy, papillary thyroid carcinoma