Lenvatinib vs. palliative therapy for stage IVC anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is an orphan disease with extremely poor prognosis. In particular, unresectable stage IVC ATC is extremely difficult to treat and is associated with a survival of only a few months, even when treated with irradiation and/or chemotherapy. In 2015, lenvatinib was approved for the treatment of ATC in Japan. The aim of the present study was to evaluate the efficacy of lenvatinib for stage IVC ATC. A total of 32 patients with pathologically confirmed stage IVC ATC who were treated at the Kanagawa Cancer Center between 2011 and 2018 were included in the present study, of whom 16 patients were treated with lenvatinib (L group). The remaining 16 patients received palliative therapy (P group), of whom 7 were treated with weekly paclitaxel, 2 received external radiation for tumor reduction 5 days per week until treatment completion, and 2 underwent tracheostomy to avoid the risk of asphyxiation. The survival curves of both groups were analyzed using the log-rank test. The median overall survival time of the L and P groups was 4.2 and 2.0 months, respectively. A significant survival benefit was observed in the L group compared with that in the P group (P=0.00298). A reduction in tumor size by ≥30% (clinical partial response) within 1 month after treatment was observed in 5 patients (31.3%) in the L group and in no patients in the P group. Therefore, lenvatinib treatment yielded a median survival benefit of ~2 months compared with palliative therapy in stage IVC ATC. However, although a reduction in tumor size by ≥30% was confirmed in 5 patients who received lenvatinib treatment, 2 of those patients succumbed to massive necrosis and bleeding. These results suggest that an appropriate lenvatinib dose reduction is necessary.