Stereotactic radiotherapy using the CyberKnife is effective for local control of bone metastases from differentiated thyroid cancer.

Chie Masaki,Kenichi Matsuzu,Takashi Uruno,Keiko Ohkuwa,Junko Akaishi,Mitsuji Nagahama,Takayuki Ishigaki,Akifumi Suzuki,Koichi Ito,Shinichiro Miyazaki,Chisato Tomoda,Wataru Kitagawa,Kiyomi Y Hames,Kiminori Sugino

doi:10.1093/jrr/rrz056

Chie Masaki, Kenichi Matsuzu + Show 12 more

Open Access

https://doi.org/10.1093/jrr/rrz056

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Abstract

ABSTRACTDifferentiated thyroid cancer (DTC) is associated with a good long-term prognosis, but bone metastases can adversely affect patients’ quality of life and survival. Stereotactic radiotherapy (SRT) can deliver high-dose irradiation to target lesions and it has been reported to be useful for various cancers. However, few studies have examined the efficacy of SRT for thyroid cancer. In the present study, the aim was to investigate the efficacy of SRT using the CyberKnife for bone metastases from DTC. From September 2013 to April 2018, SRT with the CyberKnife system was used to treat 60 bone metastases from DTC in 13 patients. The patients’ medical records were retrospectively reviewed to obtain information about the adverse events associated with SRT. Of the 60 lesions, 40 could be evaluated by follow-up CT for therapeutic effectiveness, and the RECIST criteria were used to assess the response. The cancers were papillary cancer in 3 patients, follicular cancer in 9 and poorly differentiated cancer in 1. SRT was delivered in 1–10 fractions, with a median dose of 27 Gy (range, 8–48 Gy). Adverse events were infrequent and mild. The median follow-up of the 40 lesions was 11 (range, 2–56) months. The responses were partial response in 2 lesions, stable disease in 37 lesions and progressive disease in 1 lesion, with a 1-year local control rate of 97.1%. The present study showed that SRT using the CyberKnife system was a feasible and effective treatment for bone metastases of DTC.

Highlights

Differentiated thyroid cancer (DTC) is associated with good long-term cause-specific survival (CSS)
The role of conventional external beam radiotherapy (EBRT) for bone metastasis treatment is well established, and the goals of EBRT are to remove the cause of pain, to improve paralysis or to prevent pathologic fractures or spinal cord compression [4]
We showed the usefulness of stereotactic radiotherapy (SRT) for locoregional recurrence of DTC, with a local control rate (LCR) of 84.6% at 3 years [7]

Summary

Introduction

Differentiated thyroid cancer (DTC) is associated with good long-term cause-specific survival (CSS). Radioactive iodine (RAI) therapy has been found to be associated with improved survival of patients with metastases from DTC and should be given for iodine-avid bone metastases, but RAI is rarely curative [3]. For RAI-refractory and progressive bone metastases from DTC, local therapies are required. For patients diagnosed with bone metastases, several treatment options exist for the management of local disease, including surgical intervention, radiotherapy or a combination of these therapies [1]. The role of conventional external beam radiotherapy (EBRT) for bone metastasis treatment is well established, and the goals of EBRT are to remove the cause of pain, to improve paralysis or to prevent pathologic fractures or spinal cord compression [4]. On the other hand, compared with conventional EBRT, stereotactic radiotherapy (SRT) demonstrated higher efficacy

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