Abstract
BackgroundIn this study, we investigated the relationship between clinicopathologic factors, BRAFV600E mutation status and [18F] F-fluoro-2-deoxyglucose (FDG) avidity in patients with radioiodine (RAI)-negative recurrent or metastatic differentiated thyroid cancer (DTC).MethodsFrom 2015 to 2018 all patients with suspected recurrent or metastatic radioiodine-negative DTC patients who underwent FDG positron emission tomography/computed tomography (PET/CT) were retrospectively reviewed. Suspected lesions on FDG PET/CT were biopsied and underwent BRAFV600E mutation testing by immunohistochemistry and real-time PCR. Tumor size, recurrent versus metastatic disease, histopathologic features including classical type versus aggressive subtypes (poorly differentiated, tall cell, columnar cell, hobnail variants) and BRAFV600E mutation status were correlated with the SUVmax of highest hypermetabolic lesions on FDG PET/CT by the univariate analysis using logistic regression.ResultsSixty-three consecutive patients, 55 (87.3%) female, with median age of 48 (range 17–81) were included. The majority of patients had BRAFV600E mutation and classical subtype, 55/63 (87.3%) and 45/63(71.4%), respectively. Thyroglobulin at the time of suspected recurrence was 262.7 ng/ml (range 16.3–1000) and patients received a median 3 prior RAI treatments. Fifty-four patients (85.7%) had local recurrence. The majority of patients 58/63 (92.1%) had FDG-avid disease on PET/CT. On univariate analysis, tumor size aggressive histopathologic types and distant metastasis are the significant factors for predicting FDG uptake, p = 0.04, p = 0.001 and p = 0.004 respectively. Although FDG uptake of BRAFV600E bearing recurrent/metastatic RAIR DTC lesions was higher than those without the mutation, the difference did not reach statistical significance, SUVmax of 7.11 versus 4.91, respectively, p = 0.2.ConclusionThe majority of recurrent or metastatic RAI-negative DTC have BRAFV600E mutation and detectable disease on FDG PET/CT. FDG avidity of the recurrent or metastatic RAI-negative DTC is independently associated with the aggressive histopathologic features.
Highlights
Thyroid carcinoma is one of the most popular endocrine cancer worldwide
We aimed to Patients This is a retrospective review of all patients from 2015 to 2018 who had 1) prior RAI ([131I] treatment, 2) had negative diagnostic or post-treatment iodine scan following suspected recurrent disease based on rising thyroglobulin (Tg) or ultrasound findings, 3) underwent FDG PET/Positron emission tomography/computed tomography (CT) for detection of the site of recurrence
There was no significant difference in the prevalence of BRAFV600E mutation by the histopathologic subtype of differentiated thyroid cancer (DTC), 40/45 (88.9%) in classical subtype vs. 15/18 (83.3%) in aggressive subtype (P = 0.6), respectively (Table 2)
Summary
Thyroid carcinoma is one of the most popular endocrine cancer worldwide. Differentiated thyroid cancer (DTC) accounts for 90% of all thyroid cancer types [1]. 5% of patients with DTC follow a more aggressive course with radioiodine (RAI)-refractory or RAI-negative disease, often becoming the cause of mortality associated with tumor recurrences and distant metastases [2]. These DTC patients were predicted to have poorer prognosis and limited effective treatments including surgery, radiation therapy, chemotherapy, immunotherapy and tyrosine kinase inhibitors [3]. We investigated the relationship between clinicopathologic factors, BRAFV600E mutation status and [18F] F-fluoro-2-deoxyglucose (FDG) avidity in patients with radioiodine (RAI)-negative recurrent or metastatic differentiated thyroid cancer (DTC)
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