Initial Experience with Proton Beam Therapy for Differentiated Thyroid Cancer

Nathan Y Yu; Aditya Khurana; Daniel J Ma; Michelle A Neben-Wittich; Michael A Golafshar; Lisa A McGee; Jean-Claude M Rwigema; Robert L Foote; Samir H Patel

doi:10.14338/IJPT-D-20-00053

Initial Experience with Proton Beam Therapy for Differentiated Thyroid Cancer

Int J Part Ther. 2021 Jun 25;8(1):311-318. doi: 10.14338/IJPT-D-20-00053. eCollection 2021 Summer.

Authors

Nathan Y Yu¹, Aditya Khurana², Daniel J Ma³, Michelle A Neben-Wittich³, Michael A Golafshar⁴, Lisa A McGee¹, Jean-Claude M Rwigema¹, Robert L Foote³, Samir H Patel¹

Affiliations

¹ Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA.
² Mayo Clinic Alix School of Medicine, Mayo Clinic, Scottsdale, AZ, USA.
³ Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA.
⁴ Division of Health Sciences Research, Mayo Clinic, Scottsdale, AZ, USA.

Abstract

Purpose: External 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 methods: Fourteen 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.

Results: Median 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.

Conclusion: In 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.

Keywords: intensity-modulated proton therapy; proton beam therapy; thyroid cancer.