Skeletal related events in differentiated thyroid cancer with bone metastasis: A bicentric study

We aimed to evaluate clinical features, treatment approaches and overall survival (OS) of differentiated thyroid cancer (DTC) patients with bone metastases (BM) and skeletal-related-events (SRE) (bone irradiation or surgery, spinal cord compression, pathologic fracture or hypercalcemia). In total, 178 consecutive DTC patients harbouring BM were enrolled in this retrospective study conducted in two tertiary centres between 1989 and 2015. 127 patients (71.3%) had SREs. The median time to first SRE was 13 months [0–67.5]. Seventy-six patients (66%) had multiple SRE (median: 2 (1–3)). The most frequent SRE were radiotherapy (75.6%), bone surgery (58.3%) and pathologic fractures (52%). In patients with SRE, the number of loco-regional treatments (LRT) and bones targeting agents (BTA) prescribed increased after 2005. Pathological fractures occurred in 63% (n = 34) and 51.2% (n = 40) of the patients treated before and after 2005. In multivariate analysis, only osteolysis and aggressive variants or poorly DTC were able to predict SRE (P = 0.02 and P = 0.03 respectively). Among patients with FDG-PET/CT uptake in BM, 92% patients had a SRE. The median OS after BM diagnosis was 45 months (24–81.7) for patients with SRE versus 72 months (33.7–101) for patients without. SRE didn’t impact OS in multivariate analysis. Almost two thirds of DTC patients with BM experience a SRE. Osteolysis and aggressive variants or PDTC were associated to higher risk of SRE. We observed an increased in LRT and BTA prescription after 2005 with a decreased risk of pathological fracture. Among these patients, SRE occurrence did not impact OS.