A Patient with Follicular Thyroid Cancer and a Painful Bone Metastases at Risk for Pathologic Fracture

Abstract

Distant metastases are the most important prognostic factor in differentiated thyroid cancer. In particular, bone metastases occur in less than 5 % of patients with thyroid cancer, but they often represent a frequent cause of morbidity, local pain, and neurological symptoms. The median reported overall survival in patients with bone metastases is 2–4 years after diagnosis and treatment, but it can range from 96 % at 10 years in younger patients (<45 years) with ¹³¹I-avid lesion without radiological correlate to less than 10 % in older patients with multiple lesions and radiological abnormalities. The treatment of bone metastases is challenging. Small lesions with ¹³¹I uptake and not visualized on cross-sectional imaging can be completely treated by radioactive iodine. In case of multiple lesions or large lesions and in case of bone metastases from ¹³¹I refractory thyroid cancer, radioactive iodine is not effective, and local treatments are then necessary to avoid local complications, neurological symptoms, and pathological fractures. In some cases, surgery represents the first choice to reduce the tumor burden or to treat spinal compression. In some cases, surgery may not be indicated because of general anesthesia risk, patient comorbidity, or lesion localization. Recently, local treatments such as radiofrequency ablation or cryoablation show comparable results to surgery in terms of efficacy in localized disease, and they allow for lesion stabilization in case of fracture risk when associated to cementoplasty. Furthermore, these treatments are well tolerated, they can be repeated in the same patients, and they are compatible with radioactive iodine treatment or radiotherapy if necessary. They are usually performed before starting systemic treatment such as tyrosine-kinase inhibitors or chemotherapy that typically show low efficacy in treating bone lesions. Thus, the management of thyroid cancer-related bone metastases is complex and requires a multidisciplinary approach with oncologists, surgeons, interventional radiologists, and radiotherapy team collaboration.