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Journal of Thyroid Research
Volume 2017 (2017), Article ID 9807543, 9 pages
https://doi.org/10.1155/2017/9807543
Clinical Study

18F-FDG Pet-Guided External Beam Radiotherapy in Iodine-Refractory Differentiated Thyroid Cancer: A Pilot Study

1Radiation Oncology Center, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
2Nuclear Medicine Unit, University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
3Medical Physics Department, University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
4Division of Endocrinology, University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
5Radiology Unit, Department of Experimental, Diagnostic and Specialty Medicine (DIMES), University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
6Radiation Oncology Unit, Bellaria Hospital, Bologna, Italy
7Radiotherapy Unit, Azienda Ospedaliera Universitaria Integrata, Ospedale Civile Maggiore, Verona, Italy
8Gemelli Advanced Radiation Therapy Center, Fondazione Policlinico Universitario “A. Gemelli”, Catholic University of Sacred Heart, Rome, Italy
9Radiotherapy Unit, Department of Oncology, “Giovanni Paolo II” Foundation, Catholic University of Sacred Heart, Campobasso, Italy
10Medical Physics Unit, “Giovanni Paolo II” Foundation, Catholic University of Sacred Heart, Campobasso, Italy

Correspondence should be addressed to Fabio Monari; moc.liamg@fe.aiparetoidar

Received 20 June 2017; Accepted 18 September 2017; Published 19 October 2017

Academic Editor: Massimo Tonacchera

Copyright © 2017 Eleonora Farina et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. To evaluate the clinical response rate after a postoperative 18F-FDG PET/CT guided external beam radiotherapy (EBRT) in Iodine-refractory differentiated thyroid cancer. Material and Methods. Patients with thyroid cancer locally recurrent after total thyroidectomy plus metabolic radiotherapy and treated with radical EBRT were included. Inclusion criteria were detectable thyroglobulin (Tg), negative postmetabolic radiotherapy whole body scintigraphy, and no surgical indications. The pretreatment 18F-FDG PET/CT resulted positive in all cases (loggia, lymph nodes, and lung). EBRT was delivered with IMRT-SIB technique. A 18F-FDG PET/CT revaluation and Tg dosage were performed 3 months after the treatment. Results. Sixteen consecutive patients were included in this analysis (median follow-up: 6–44 months). Post-EBRT 18F-FDG PET/CT showed CR in 43.7%, PR in 31.2%, SD in 25.0% patients, and PD due to lung metastases in 12.5%. Overall response rate was 75.0% (CI 95%: 41.4–93.3%). Tg levels decreased in 75.0% with a median Δ of 68.0%. Two-year PFS and OS rates were 80.0% and 93.0%, respectively. Acute G3 toxicity occurred in 18.7% and late G2 toxicity in 12.5%. Conclusions.  18F-FDG PET/CT was useful in target definition for radiotherapy planning, identifying positive areas not detected with 131I scintigraphy. IMRT based EBRT was feasible and our results encourage future prospective studies. This clinical trial is registered with ID: NCT03191643.