Dramatic Response of S-1 Administration to Chemorefractory Advanced Thymic Cancer

Thymic cancer (TC) is a rare malignancy in thoracic tumors, and there has been no standard therapeutics for advanced or relapsed patients. The clinical significance of second-line or beyond chemotherapy for platinum refractory advanced TC remains unclear. Here, we present the experience of a patient with TC showing a complete response to S-1 as third-line chemotherapy. A 54-year-old female with TC was treated with carboplatin plus paclitaxel and thoracic radiotherapy as first-line chemoradiotherapy and amrubicin as second-line chemotherapy. After 3 cycles of amrubicin administration, the metastatic hepatic lesions revealed a markedly progressive disease. A single agent of S-1 was administered as sequencing chemotherapy. After 2 cycles of S-1, the patient achieved a complete remission of multiple metastatic sites. There was evidence of immunohistochemical staining of a low thymidylate synthase (TS) expression. The expression of TS may be closely associated with the efficacy of S-1 in patients with TC.