Clinicopathological evaluation of pre-operative chemoradiotherapy with S-1 as a treatment for locally advanced oral squamous cell carcinoma

Abstract

The administration of pre-operative chemotherapy with S-1 and concurrent radiotherapy at a total dose of 30 Gy was clinicopathologically evaluated as a treatment for locally advanced oral squamous cell carcinoma (OSCC) in the present study. The participants comprised 81 patients with OSCC, consisting of 29 patients with stage II disease, 12 patients with stage III disease and 40 patients with stage IV disease. All patients received a total radiation dose of 30 Gy in daily fractions of 2 Gy, 5 times a week, for 3 weeks, and the patients were concurrently administered S-1 at a dose of 80-120 mg, twice daily, over 4 consecutive weeks. Radical surgery was performed in all cases at 2-6 weeks subsequent to the end of pre-operative chemoradiotherapy. The most common adverse event was oropharyngeal mucositis, but this was transient in all patients. No severe hematological or non-hematological toxicities were observed. The clinical and histopathological response rates were 70.4 and 75.3%, respectively. Post-operatively, local failure developed in 6 patients (7.4%) and neck failure developed in 2 patients (2.5%). Distant metastases were found in 7 patients (8.6%). The overall survival rate, disease-specific survival rate and locoregional control rate at 5 years were 87.7, 89.9 and 90.6%, respectively. Locoregional recurrence occurred more frequently in patients that demonstrated a poor histopathological response compared with patients that demonstrated a good response (P<0.01). These results indicate that pre-operative S-1 chemotherapy with radiotherapy at a total dose of 30 Gy is feasible and effective for patients with locally advanced OSCC, and that little or no histopathological response may be a risk factor for locoregional recurrence in this treatment.

Keywords: S-1; chemoradiotherapy; oral squamous cell carcinoma; preoperative treatment; survival rate.

Figure 1.

Summary of the pre-operative chemoradiotherapy regimen with S-1 administered for the treatment of patients with locally advanced oral squamous cell carcinoma.

Figure 2.

Survival and locoregional control rates of patients with locally advanced oral squamous cell carcinoma. (A) The LRC, DSS and OS rates at 5 years were 87.7, 89.9 and 90.6%, respectively. (B) A significant difference was identified between the 5-year DSS rates in stages II and III/IV of disease (100.0 vs. 84.0%; P<0.05). Statistical analysis was performed using the log-rank test. NS, not significant; LRC, locoregional control; DSS, disease-specific survival; OS, overall survival.