Bone metastases (BM) are frequent in differentiated thyroid cancer (DTC), affecting the skeleton at various extents, impacting negatively quality of life, being the leading cause of DTC-related morbidity and death. We aimed to evaluate (a) the overall survival (OS) and (b) assess predictive factors of radioiodine treatment (RAI) response in patients with DTC and BM.
178 consecutive DTC patients harboring BM were enrolled in this retrospective study conducted in two tertiary referral centres of the French national TUTHYREF network between 1989 and 2015. OS analysis was performed for the whole cohort while the 145 non-RAI refractory patients at BM diagnosis were evaluated for total RAI response (T-RAI-R) defined as the complete resolution of RAI uptake in the absence of morphologic progression of BM.
The median OS, calculated from BM diagnosis, was 57 months (24-93). The OS rate at 5 and 10 years from BM detection was 56.5% and 15.3% respectively for patients with BM RAI uptake but only 28.6 and 4.8% for patients without any significant radioiodine uptake. In multivariate analysis, OS was significantly reduced by T4 stage, BM FDG-PET/CT uptake and RAI refractory status (HR, 2.91; 95% CI, 1.27-6.65, p=0.113; HR, 3.79; 95% CI 1.23-11.71, p=0.0204; HR, 5.16; 95% CI 1.21- 21.93, p=0.0264, respectively). Among the 145 DTC non-RAI refractory patients at BM diagnosis, 46 patients (31.7%) achieved a T-RAI-R (32 patients with radioiodine alone and 14 with further local BM treatments). Patients without extra-skeletal metastasis and absence of BM FDG-PET/CT uptake were more likely to achieve T-RAI-R (OR, 0.11; 95% CI, 0.02-0.46, p=0.005; OR, 0.2; 95% CI, 0.04-0.80, p=0.0236, respectively).
Among DTC patients with newly diagnosed BM. BM FDG-PET/CT uptake is a prognostic factor for a T-RAI-R and for OS. FDG-PET/CT should be performed as soon as the BM diagnosis.
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All authors have declared no conflicts of interest.