Combined BRAFV600Eanalysis and99mTc-MIBI scintigraphy can be a useful diagnostic tool in differentiated thyroid cancer patients with incomplete bio-chemical response to first radioiodine therapy (RAIT): a pilot investigation

Purpose The aim of the present study was to evaluate the possible diagnostic role of the combined performance of BRAF mutation analysis and MIBI scintigraphy in papillary thyroid cancer (PTe) patients with incomplete bio-chemical response to first radioiodine therapy (RAIT) performed for thyroid remnant ablation. Methods The records of 15 PTC patients with bio-chemical incomplete response to first RAIT were retrospectively analyzed. BRAFv600E analysis on primary tumor samples was obtai ned in ali cases along with neck ultrasonography and 99mTc_MIBI scintigraphy of the neck-thorax regions at first follow-up. Ali patients then underwent RAIT with high rad ioiodine activities. A post-therapy whole-body scan (pT-WBS) was acquired 5- 7 days after RAlT. Results Abnormal radioiodine uptake was found in IO out of the 15 patients (67%. I3 ll+ve). while in the remaining 33%. no abnormal radioiodine uptake was detected (5/15, 13I I_ve). Abnormai tracer uptake was found in 6 out of IO 13I I+ve patients at 99mTc_MIBI scintigraphy (MIBI+ve). BRAFv600E mutation was not found in the majority of 13Il+ve paticnts (9 out of lO BRAFv600E_ ve) . On the contrary, in the 5 13II_ve patients, 99mTc_MIBI scintigraphy did not show any abnormal tracer uptake (MIBI-ve), while BRAFv600E mutation was present (BRAFv600E+ve). Thus, in our series, the association between MiBI- ve scintigraphy and BRAF+ve mutation was a useful diagnostic tool in predicting negative pT-WBS outcome. Conclusion Albeit obtained in a small retrospective series, our results suggest that the combination of BRAFv600E+ve mutation and MIBI-ve sci ntigraphy may be considered a negative prognostic cl ue, which predicts the absence of radioiodine uptake at pT-WBS in OTC patients with incomplete bio-chemical response to first RAIT.