The primary endpoint will be 2-years distant failure rate which will be estimated by Kaplan-Meier method with two-sided 95% confidence interval.~The secondary endpoints are described as follows:~2-year locoregional failure rate, 2-year PFS rate and 2-year OS rate will be estimated by Kaplan-Meier method with two-sided 95% confidence interval.~Safety profile: adverse events will be summarized by CTCAE. Safety parameters will only be analyzed on the safety analysis set and be presented in frequency tabulation.~Determination of sample size:~The estimated 2-year distant failure rate for squamous cell carcinoma of oral cavity with extracapsular spreading of lymph nodes is 26%. The 2-year distant failure rate of maintenance treatment with tegafur-uracil in this study is expected to be 13%. Using One Proportional Test with one-sided alpha 0.05 and power 80%, the sample size of 56 subjects will test an effect size of 13% (i.e. 26% vs.13%). With expected dropout rate of 20%, the sample size would be 68 subjects.
Primary Objective:~To determine the 2-year distant failure rate of maintenance tegafur-uracil in patients with squamous cell carcinoma of oral cavity with extracapsular spreading of lymph nodes.~Secondary Objectives:~To determine the 2-year locoregional failure rate.~To evaluate the 2-year overall survival (OS) rate.~To evaluate the 2-year progression-free survival (PFS) rate.~To assess the safety profiles.