PP184: Preoperative chemotherapy with S-1 for T1–2N0 oral squamous cell carcinoma patients

Purpose Surgery is a main therapeutic modality for T1–2N0 oral squamous cell carcinoma (OSCC). But almost patients have to wait for 2–4 weeks from histological diagnosis to definitive surgery with circumstances of hospital. S-1 is oral fluorouracil, containing tegaful (prodrug of 5-FU) and two biochemical modulators, and effective for OSCC. We administered S-1 to these patients during waiting for surgery to inhibit tumor growth and dissemination, and investigated the effect of S-1 on prognosis. Materials and methods T1–2N0 OSCC patients who have to wait surgery more than 2 weeks from histological diagnosis were administered S-1 (80 mg/m 2 /day) until surgery. We analyzed 48 patients who took S-1 orally more than 7 days about anti-tumor effect and prognosis. Results Mean administration period was 15.9 days (7–42 days), and mean total dosage was 1705.4 mg. Clinical anti-tumor effect was CR:7, PR:7 and NC:34 patients. The clinical response rate was 29.2%. Histological anti-tumor effect was CR:6, PR:11 and NC:31 patients and histological response rate was 35.4%. Local recurrences and late metastases were seen in three patients (6.3%) and 9 patients (18.8%), respectively. Histological NC cases developed local recurrence (9.7%) and late metastasis (25.8%) whereas almost patients who revealed CR or PR did not. Three-year survival rate was 100% in CR and PR cases, and 87.8% in NC cases. Adverse effects more than grade 2 were not appeared. At least 2-weeks administration is necessary to obtain anti-tumor effect. Conclusions In histologically effective cases, development of local recurrence and late metastasis was very low and prognosis is excellent. The short term administration of S-1 during waiting surgery is safe and useful for early stage OSCC patients.