Usefulness of CyberKnife Therapy in Patients with Differentiated Thyroid Cancer with Distant Metastases

Abstract

ABSTRACT Aim and objective We reported seven cases in which external beam radiotherapy (EBRT) with CyberKnife therapy was effective against distant metastases from differentiated thyroid carcinoma (DTC). Materials and methods The subjects included seven patients (6 males, 1 female; age 53–77 years, average age 65.85 years) who underwent CyberKnife therapy for metastatic lesions of DTC (pathological diagnosis: differentiated papillary carcinoma). The target lesions included 12 lymph node, 6 bone, and 2 brain metastases. All patients had previously undergone total thyroidectomy, followed by radioactive iodine therapy (RAIT). Since RAIT was not expected to have a therapeutic effect, CyberKnife treatment was selected. CyberKnife irradiation was performed 1–5 times. The radiation doses covering 95% of the planning target volume (D95) ranged from 15 to 26 gray (Gy). To determine the therapeutic effect, lesion size was evaluated by computed tomography (CT) and magnetic resonance imaging (MRI) before and 6–12 months after treatment. Results No increase in size was observed in the brain and bone metastases. Among the lymph node metastatic lesions, a therapeutic effect involving internal necrosis without an increase in size was noted in two lymph node metastases in the cervix. Additionally, two lymph node metastases in the neck had reduced in size. No increases in size were observed in the other lymph node lesions, reflecting the therapeutic effect of CyberKnife. Conclusions CyberKnife may be useful in treating distant metastatic lesions of papillary thyroid cancer. Clinical significance CyberKnife is useful as a multidisciplinary treatment for cases in which radioactive iodine therapy is maladjusted. How to cite this article Higashiyama S, Yoshida A, Katayama Y, et al. Usefulness of CyberKnife Therapy in Patients with Differentiated Thyroid Cancer with Distant Metastases. Int J Otorhinolaryngol Clin 2020;12(2):38–41.