Abstract
PurposeExternal beam radiotherapy is used in a subset of high-risk patients with differentiated thyroid cancer (DTC). Recurrent, radioactive iodine (RAI)–refractory DTC carries a poor prognosis. We report our initial experience of intensity-modulated proton therapy (IMPT) for recurrent, RAI-refractory DTC.Patients and MethodsFourteen patients with recurrent, RAI-refractory DTC were consecutively treated with IMPT from November 2016 to March 2020 at our multisite institution. Patient, tumor, and treatment characteristics were recorded. Overall survival and local-regional recurrence-free survival were recorded and estimated using the Kaplan-Meier method. Acute and late treatment-related toxicities were recorded based on the Common Terminology Criteria for Adverse Events version 5.0. Patients completed the European Organization for Research and Treatment of Cancer Quality of Life Head and Neck Module at baseline and after IMPT. Eleven patients were included in the final analysis.ResultsMedian follow-up was 8 months (range, 3-40) for all patients. Median age at treatment with IMPT was 64 years (range, 40-77), and the majority were men (64%). Recurrent histologies included papillary (55%), Hurthle cell (36%), and poorly differentiated (9%) carcinoma; 1 patient had tall cell variant. Concurrent chemotherapy was not administered for any patient in this cohort. At 8 months, all patients were alive without local-regional failure. Acute grade 3 toxicities were limited to 1 patient with dysphagia, requiring feeding tube placement. Two patients experienced late grade 3 esophageal stenosis requiring dilation. There were no grade 4 or 5 toxicities. There were no differences in pretreatment versus posttreatment patient-reported outcomes in terms of dysphagia or hoarseness.ConclusionIn our early experience, IMPT provided promising local-regional control for recurrent, RAI-refractory DTC. Further study is warranted to evaluate the long-term efficacy and safety of IMPT in this patient population.
Highlights
IntroductionDifferentiated thyroid cancer (DTC) accounts for the vast majority of thyroid cancer
Researchers projected that approximately 53,000 new cases of thyroid cancer would occur in the United States in 2020 and that the incidence is increasing 3% per year [1, 2].Downloaded from http://meridian.allenpress.com/theijpt/article-pdf/8/1/311/2880232/i2331-5180-8-1-311.pdf by guest on 02 November 2021Proton beam therapy (PBT) for differentiated thyroid cancerDifferentiated thyroid cancer (DTC) accounts for the vast majority of thyroid cancer
Treated adults 18 years old with recurrent, radioactive iodine (RAI)-refractory DTC treated with intensity-modulated proton therapy (IMPT) with curative intent were included in this study
Summary
Differentiated thyroid cancer (DTC) accounts for the vast majority of thyroid cancer. Standard-of-care treatment for de novo DTC is surgical resection with adjuvant radioactive iodine (RAI) therapy (I-131) in selected patients and thyroid hormone suppression therapy. There are few effective treatments for locally or regionally recurrent, RAI-refractory DTC. Most patients with recurrent DTC undergo salvage surgical resection with potential additional RAI and percutaneous ethanol ablation [16,17,18,19]. EBRT has been used in patients with RAI nonavid or refractory disease, in patients with gross residual or unresectable primary or recurrent disease, and in high-risk patients .45 years old [3,4,5]
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