Adjuvant chemo-endocrine therapy for breast cancer (ACETBC) trial has been the first large scaled clinical trial performed in Japan. Several prospective randomized trials have been performed in Japan since ACETBC-1 trial started in 1985. The effect of oral 5-FU agents had been tested in prospective randomized trials and the statistically marginal effect of oral 5-FU agents in adjuvant settings has been reported. Several trials having CMF as a control arm started in 1996 when CMF combination chemotherapy was approved by the government. The results of these trials have not been published. To perform good clinical trials, it is imperative to construct infrastructures including clinical research coordinator, and abolish governmental regulation of the dose of anticancer agents.