Objective: Tyrosine kinase inhibitors (TKIs) are used to treat patients with advanced thyroid cancers. We retrospectively investigated the efficacy of TKIs administered outside of clinical trials in metastatic sites or locally advanced thyroid cancer patients from five French oncology centers. Design and methods: There were 62 patients (37 men, mean age: 61 years) treated with sorafenib (62%), sunitinib (22%), and vandetanib (16%) outside of clinical trials; 22 had papillary, five had follicular, five had Hü rthle cell, 13 had poorly differentiated, and 17 had medullary thyroid carcinoma (MTC). Thirty-three, 25, and four patients were treated with one, two, and three lines of TKIs respectively. Primary endpoints were objective tumor response rate and progression-free survival (PFS). Sequential treatments and tumor response according to metastatic sites were secondary endpoints. Results: Among the 39 sorafenib and 12 sunitinib treatments in differentiated thyroid carcinoma (DTC) patients, partial response (PR) rate was 15 and 8% respectively. In the 11 MTC patients treated with vandetanib, 36% had PR. Median PFS was similar in second-line compared with first-line sorafenib or sunitinib therapy (6.7 vs 7.0 months) in DTC patients, but there was no PR with second-and third-line treatments. Bone and pleural lesions were the most refractory sites to treatment. Conclusions: This is the largest retrospective study evaluating TKI therapies outside of clinical trials. DTC patients treated with second-line therapy had stable disease as best response, but had a similar median PFS compared with the first-line treatment.

Additional low dose acquisition in prone position should be performed in all patients presenting with focal PT in a dependent and basal location. This may allow to exclude a pleural plaque in case of asbestos exposure but also a pleural metastasis in oncologic patients. These reversible dependent PTs could be related to physiological focal accumulation of lymphatic fluid in subpleural area.

6092 Background: Tyrosine kinase inhibitors (TKI) are currently used to treat patients with advanced iodine-refractory differentiated thyroid cancers (DTC) but none has been approved by the FDA or the EMA until now. Sometimes, patients are treated with off-label TKI when a clinical trial is not available or in second- and third-line therapy. Methods: We hereby report the efficacy of “off-label” sorafenib and sunitinib treatments as first-, second- and third-line therapy in metastatic DTC patients from the French TUTHYREF (TUmeurs THYroïdiennes REFractaires) network. Primary endpoints were progression free survival (PFS) and tumor response according to sequential TKI treatment. Secondary endpoint was organ-specific metastatic site analysis. Results: 45 patients with advanced iodine-refractory DTC treated with off-label TKI were included in this study (26 men, mean age: 62 years). 22 had papillary, 10 had follicular and 13 had poorly DTC. 24/45 patients were treated with two and 3/45 with three lines of TKIs. Sorafenib was the most frequently used (57%) followed by sunitinib (21.5%) and vandetanib (21.5%). Partial response (PR) rate was of 29% in the 21 patients who received first-line sorafenib therapy whereas PR was observed in 57% of the 7 first-line sunitinib patients. There was no PR with second- (n=24) and third-line (n=3) treatments. However, median progression free survival (PFS) was similar in second- as compared to first-line sorafenib or sunitinib treatment (6.7 vs. 7.6 months, HR 0.85 (95CI 0.45-1.61) p=0.6). Liver metastases were the most responsive to treatment (n=7; mean of -30%), followed by lung (n=57; mean of -19%) and lymph node (n=43; mean of -13%) metastases. Bone (n=14) and pleural (n=9) lesions were the most refractory to treatment (mean of -1% and -5%, respectively). Conclusions: Due to the small number of patients, we could not recommend a specific treatment sequence (sorafenib then sunitinib) over another (sunitinib then sorafenib). But TKI therapy appears to be beneficial in refractory DTC patients even in second- and third-line therapy, with similar PFS and stable disease as best response. Bone and pleural metastases were the most refractory and liver lesions the most responsive to treatment.

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