PET Imaging in Recurrent Medullary Thyroid Carcinoma

Giorgio Treglia,Luca Giovanella,Vittoria Rufini,Massimo Salvatori,Alessandro Giordano

doi:10.1155/2012/324686

Abstract

Purpose. To perform an overview about the role of positron emission tomography (PET) or PET/computed tomography (PET/CT) using different radiopharmaceuticals in recurrent medullary thyroid carcinoma (MTC) based on biochemical findings (increased tumor marker levels after primary surgery). Methods. A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus, and Embase databases through February 2012 regarding PET or PET/CT in patients with recurrent MTC was performed. Results. Twenty-nine studies comprising 714 patients with suspected recurrent MTC were retrieved. Twenty-seven articles evaluated the role of fluorine-18-fluorodeoxyglucose (FDG) PET or PET/CT in recurrent MTC with conflicting results. Diagnostic accuracy of FDG-PET and PET/CT increased in MTC patients with higher calcitonin and carcinoembryonic antigen values, suggesting that these imaging methods could be very useful in patients with more advanced and aggressive disease. Eight articles evaluated the role of fluorine-18-dihydroxyphenylalanine (FDOPA) PET or PET/CT in recurrent MTC reporting promising results. Overall, FDOPA seems to be superior but complementary compared to FDG in detecting recurrent MTC. Few studies evaluating other PET tracers are also discussed. Conclusions. PET radiopharmaceuticals reflect different metabolic pathways in MTC. FDOPA seems to be the most useful PET tracer in detecting recurrent MTC based on rising levels of tumor markers. FDG may complement FDOPA in patients with more aggressive MTC.

Highlights

Medullary thyroid carcinoma (MTC) is a slow-growing neuroendocrine tumor originating from parafollicular C cells
A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus, and Embase databases through February 2012 regarding positron emission tomography (PET) or PET/computed tomography (PET/CT) in patients with recurrent medullary thyroid carcinoma (MTC) was performed
FDG-PET and PET/CT should not be considered as first-line diagnostic imaging methods in patients with suspected recurrent MTC, but could be very helpful in detecting recurrence in those patients in whom a more aggressive disease is suspected

Summary

Introduction

Medullary thyroid carcinoma (MTC) is a slow-growing neuroendocrine tumor originating from parafollicular C cells. MTC accounts for approximately 5% of thyroid carcinomas, occurring in either sporadic (75% of cases) or familial forms (25% of cases). This tumor is frequently aggressive; most frequent sites of metastatic disease are cervical and mediastinal lymph nodes, lungs, liver, and bone. The main treatment for MTC is surgical resection that is the only strategy for potential cure; in patients with metastatic disease therapeutic options are limited as this tumor does not concentrate radioiodine and shows poor response to chemotherapy and radiation therapy [1]. Serum calcitonin and CEA doubling times are efficient tools for assessing tumor progression and are useful prognostic factors of survival in patients with MTC [1]

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