Outcomes of patients with bone metastases from differentiated thyroid cancer

ABSTRACT Objective Bone metastases (BM) from differentiated thyroid cancer (DTC) are associated with poor survival rates. Due to the low frequency of this entity, we performed a multicentric retrospective study that aimed to evaluate the presentation, outcome and causes of death in this population. Subjects and methods We reviewed file records from 10 databases. BM were diagnosed by: i) biopsy and/or ii) radioiodine (RAI) bone uptake + elevated thyroglobulin (Tg) levels and/or c) bone uptake of 18-FDG in the PET-CT scan + elevated Tg levels. Results Fifty-two patients with DTC were included (44% male, mean age 54 years); 58% had papillary histology. BM were synchronous with DTC diagnosis in 46% of the participating cases. BM were symptomatic in 65% of the cases. Multiple BM were present in 65% of patients, while simultaneous metastatic disease in additional sites was found in 69%. Ninety-eight percent of patients received treatment for the BM, which included RAI therapy in 42 patients; 30 of them received cumulative RAI doses that were larger than 600 mCi 131I. The mean follow-up after a BM diagnosis was 34 months. The 2- and 5-year survival rates after diagnosis of the first BM were 64% and 38%, respectively. The status on the last evaluation was DTC-related death in 52% of the patients; 26% of them died from direct complications of BM or their treatments. Conclusion BM are usually radioiodine-refractory and are associated with a short overall survival, although most of the patients died of causes not directly related to the BM.

摘要
目的 分化型甲状腺癌（differentiated thyroid cancer, DTC）骨转移（bone metastases, BM）患者的生存预后较差。鉴于该病症发病率较低，本研究开展多中心回顾性分析，旨在评估该人群的临床表现、疾病转归及死亡原因。
对象与方法 本研究回顾分析了10个数据库的病历档案。骨转移的诊断标准包括：① 组织活检证实；② 放射性碘（radioiodine, RAI）骨摄取伴甲状腺球蛋白（thyroglobulin, Tg）水平升高；③ PET-CT扫描显示18-氟代脱氧葡萄糖（18-FDG）骨摄取伴甲状腺球蛋白（Tg）水平升高。
结果 本研究共纳入52例分化型甲状腺癌骨转移患者，其中男性占比44%，平均年龄54岁；58%的患者病理亚型为乳头状癌。46%的患者骨转移与分化型甲状腺癌诊断同步发生。65%的患者骨转移存在临床症状。65%的患者存在多发性骨转移，69%的患者同时合并其他部位远处转移。98%的患者接受了骨转移相关治疗，其中42例接受了放射性碘治疗；30例患者的累积放射性碘剂量超过600 mCi ¹³¹I。骨转移确诊后的平均随访时长为34个月。首诊骨转移后2年及5年生存率分别为64%和38%。末次随访时，52%的患者死于分化型甲状腺癌相关死亡；其中26%的患者直接死于骨转移及其治疗的并发症。
结论 分化型甲状腺癌骨转移多为放射性碘难治性，且整体生存期较短，但多数患者的死因并非直接与骨转移相关。