Evaluation of TS-1 based treatment and expression of thymidylate synthase and dihydropyrimidine dehydrogenase on oral squamous cell carcinoma

Seventeen oral squamous cell carcinoma (SCC) patients underwent chemotherapy with TS-1 (8 males and 9 females, mean age; 75.1 years, range; 47–102 years). TS-1 permitted five cases of oral chemotherapy on an outpatient basis and 8 cases in elder patients over 80-years of age. Excepting five patients who underwent TS-1 therapy as post-operative adjuvant chemotherapy, the therapeutic efficacy of TS-1 in 12 patients with or without irradiation, surgery or chemotherapy resulted in 3 cases of complete response (CR), 6 cases of partial response (PR), 3 cases of stable disease (SD), with no progressive disease (PD) cases (overall response rate; 75%). SCC samples obtained from biopsy were immunohistochemically stained with anti-TS and DPD polyclonal antibody. Although the statistical significance was not clear, the expression of TS and DPD for CR cases was lower than that for SD cases. TS-1 therapy improved quality of life (QOL) especially in elder patients with oral SCC, and our immunohistochemical results suggested the predictive possibilities of TS and DPD expression in response to TS-1.