The value of cyclophosphamide/methotrexate/ 5-fluorouracil (CMF)-type regimens in surgical adjuvant therapy in certain subsets of patients with axillary lymph node-negative breast cancer has been evaluated in Europe and the USA. However, Japan has a distinctive standpoint regarding the indications for surgical adjuvant chemotherapy for breast cancer patients. In addition, oral fluoropyr-imidines are widely used to treat breast cancer patients in both adjuvant and metastatic settings due to their low toxicity and convenience for long-term administration. Although the antitumor activity and the ability to prolong disease-free survival times of oral fluoropyrimidines have been evaluated in patients with breast cancer, available data are not sufficient to justify replacing CMF-type regimens with oral fluoropyrimidines in postoperative chemotherapy for breast cancer patients. To evaluate the utility of oral fluoropyrimidines in surgical adjuvant chemotherapy, the National Surgical Adjuvant Study Group (N-SAS) was founded in 1995 as a government-funded research group, and nationwide multiinstitutional trials were designed for breast cancer as well as colon and gastric cancers. For high-risk, node-negative breast cancer patients, a prospective randomized trial of surgical adjuvant chemotherapy comparing 6 cycles of CMF with 2 years of daily uracil/tegafur (UFT) started in October 1996. The endpoints of this study include disease-free and overall survival, adverse reactions, quality of life, and cost.