BRAF V600E Mutation in Papillary Thyroid Cancer and Its Effect on Postoperative Radioiodine (131I) Therapy: Should We Modify Our Therapeutic Strategy?

Abstract

IntroductionThe BRAF V600E mutation in papillary thyroid cancer (PTC) has been associated with resistance to 131I. Our aim was to quantify the response to 131I after surgery in patients who had the mutation (BRAF+) and those who did not have the mutated gene (BRAF−). MethodA prospective cohort study was designed, from September 2015 to February 2016, which included patients with PTC receiving therapy after surgical treatment. Variables were described for age, gender, histology, tumor stage, thyroglobulin values before, 48h after and 6 months after 131I; absorbed dose and % activity on days 2 and 7 and elimination time. Results41 patients giving in total 67 thyroid remnants were included. 61% were BRAF+. In stages III and IV, 80% were BRAF+. In lateral resection, 100% were BRAF+. The number of nodes was higher in BRAF+: 3.4 vs 1.2 (P=.01). The classic variant was predominant in BRAF+ (91.7% vs 8.3%, P=.03). 85.7% vs 14.3% of BRAF+ had desmoplastic reaction (P=.02). The BRAF+ had a lower absorbed dose than the administered activity (5.4Gy/MBq vs 20Gy/MBq, P=.02); lower% activity with respect to the unit of mass at 2 (0.046%/g vs 0.103%/g, P=.02) and at 7 days (0.006%/gr vs 0.034%/gr, P=.04). ConclusionsThe mutation of the BRAF V600E gene is related with greater resistance to postoperative treatment with 131I since the onset of the disease.