The standard treatment for thyroid cancer is surgery. For cases of differentiated thyroid cancer that are inoperable or have distant metastases, radioactive iodine therapy is also an option. However, there were no effective treatments for medullary thyroid cancer or anaplastic thyroid cancer until now. Recently, a new treatment option, multi-tyrosine kinase inhibitors (mTKIs), has emerged. This is good news for cases that previously had no treatment options, but mTKIs come with many adverse effects, making management difficult. In recent years, new selective tyrosine kinase inhibitors have also become available. In Japan, the incidence of thyroid cancer is on the rise, and given the long prognosis even after distant metastasis, drug therapy is expected to play a significant role. Therefore, we report on drug therapy for thyroid cancer at our department.

From 2016, we treated 29 cases of thyroid cancer with molecular targeted drugs at our department. The histological types were 18 cases of papillary carcinoma, 5 cases of follicular carcinoma, 2 cases of poorly differentiated carcinoma, 2 cases of medullary carcinoma, and 2 cases of anaplastic carcinoma. The initial treatments included 20 cases with lenvatinib, 6 with sorafenib, 2 with vandetanib, and 1 with selpercatinib. Genetic testing was conducted in 7 cases, with 3 cases identifying causative genes (BRAF V600E in 1 case, RET in 1 case, and RET fusion in 1 case). The best response rates for the initial drugs were CR in 4 cases, PR in 4 cases, SD in 11 cases, PD in 5 cases, and unknown in 5 cases. The 5-year overall survival rate from the start of molecular targeted therapy was 25.8%.

We will report on the above, including a literature review.