Current status of chemotherapy for advanced colorectal cancer in Japan.

Treatment policies for metastatic colorectal cancer (CRC; mCRC) are similar in Japan and in Western countries. An important goal is the global development of new molecular-targeted drugs. To achieve this goal, controlled clinical trials should be performed to determine whether S-1, an oral dihydropyrimidine dehydrogenase inhibitory fluoropyrimidine, can replace 5-fluorouracil for the treatment of CRC. On the other hand, the use of adjuvant chemotherapy differs slightly between Japan and Western countries. An underlying reason is the difference in surgical results. In Japan, the use of adjuvant chemotherapy with oral fluoropyrimidines evolved independently from developments in Western countries. However, clinical studies of adjuvant chemotherapy require more patients and longer follow-up periods than clinical studies of mCRC. The use of international collaborative clinical trials is essential to ensure that more effective drugs will be promptly provided to patients in every country. Improved quality control of surgery in patients participating in clinical trials or a better collective understanding of the quality of centers performing such studies will most likely facilitate the design of international collaborative clinical trials. International meetings, including the participation of oncologists and surgeons, should be held in the near future to promote collective understanding and the design of high-quality clinical studies.