Treatment outcomes of differentiated thyroid cancer with distant metastasis improve by tyrosine kinase inhibitors.

In patients with distant metastasis, treatment for differentiated thyroid cancer (DTC) includes complete total thyroidectomy, followed by radioactive iodine (RAI) therapy for metastatic lesions. Tyrosine kinase inhibitor (TKI) treatment is the final treatment option for metastatic lesions, which is incurable with surgery/RAI therapy. The present study examined whether treatment outcomes for DTC in patients with distant metastasis improved following TKI treatment. This study included 147 patients (median age, 71; range, 33-91 years) who underwent surgery in our hospitals and were diagnosed with distant metastasis. Disease progression was observed in 70 patients, of whom 56 were treated with TKI (TKI group); 14 refused TKI treatment or showed no treatment indication [untreated (UT) group]. Disease progression and treatment outcomes were assessed using imaging evaluations. The present study investigated thyroglobulin doubling time (Tg-DT) and Tg antibody presence/absence and their relation to disease progression. Overall survival following disease progression between the two groups was compared. The study included 22 cases of sorafenib, 49 of lenvatinib, and 15 involving TKIs. The mean dosing period for sorafenib was 153 days and for lenvatinib was 462 days. In the TKI group, 16, 26, and 9 patients exhibited partial responses (PRs), stable disease (SD), and progressive disease (PD), respectively, whereas 5 patients were not evaluable. The disease control rate (DCR) (PR+SD) was 75.0%. A total of 16 patients died in the TKI group, whereas 10/14 patients in the UT group died. Survival curves for the groups were significantly different. TKI treatment improved the prognosis of patients with distant metastasis and PD.