Spindle cell carcinoma after irradiated oral squamous cell carcinoma treated with S-1

Spindle cell carcinoma is considered a subtype of squamous cell carcinoma. There is no effective chemotherapy for cases of recurrence after first-line treatment, and the prognosis is poor. The patient was an 85-year-old man with spindle cell carcinoma after irradiated squamous cell carcinoma of the left lower gingiva. Extended surgery was performed, but 1 month postoperatively recurrence in the contralateral lower lip, cervical lymph node metastasis, and liver metastasis were detected, and treatment with S-1 was started. After 1 month of treatment, the cervical lymph node metastasis had resolved, and the liver metastasis had regressed, but after 4 months of treatment new cervical lymph node metastasis, lung metastasis, and rapid enlargement of the liver metastasis were observed, and led to the patient's death. Treatment with S-1 alone had an adequate antitumor effect temporarily. Further chemotherapeutic trials including S-1 are recommended to treat spindle cell carcinoma.