Retrospective Evaluation of Bone Metastases in Patients With Thyroid Malignancy: A Single-Center Experience

Background Thyroid cancer is one of the five most common cancers causing bone metastasis. If there is an increase in serum thyroglobulin-antithyroglobulin levels in differentiated thyroid cancer or calcitonin levels in medullary thyroid cancer, patients should be evaluated for recurrence and distant metastasis. The skeleton is the second most common site of distant metastasis in thyroid cancer after the lung. Bone metastases cause pain, fractures, and spinal cord compression, severely reducing the quality of life. They are associated with poor prognosis. Bone metastases severely reduce the quality of life. This study aimed to retrospectively evaluate the diagnosis and follow-up of patients with thyroid cancer with bone metastases diagnosed at our center. Methodology A total of 1,390 patients diagnosed with thyroid malignancy at our center between 2010 and 2023 were reviewed retrospectively. The study included 27 patients with differentiated and medullary thyroid cancer who had bone metastases. Results Of 27 patients, 19 (70.4%) had differentiated and eight (29.6%) had medullary thyroid cancer. Papillary thyroid cancer constituted 22.2% (n = 6) and follicular thyroid cancer constituted 14.8% (n = 4) of the cases. Papillary carcinoma follicular variant, oncocytic, and poorly differentiated thyroid cancer were diagnosed with similar frequency, each accounting for 11.1% (n = 3). It was found that vertebrae were most commonly involved, followed by the pelvis, sternum, costae, femur and patella, shoulder and humerus, cranium, and scapula. The five-year survival rate was 72%, and the 10-year survival rate was 53%. Conclusions The number of patients with papillary cancer was the highest, but the rate of bone metastases was the lowest in this group. The highest rate of bone metastases was found in patients with poorly differentiated, oncocytic, medullary, follicular, and papillary cancer, respectively. The results obtained in this study reveal the necessity and importance of bone metastasis evaluation in patients with thyroid cancer.