[Problems of randomized controlled study on surgical adjuvant chemotherapy for colorectal cancer in Japan]

There were many clinical trials to evaluate the significance of surgical adjuvant chemotherapy for colorectal cancer, but large-scale randomized controlled study was limited in Japan. From results of these trials, the effectiveness of adjuvant chemotherapy for colorectal cancer remained controversial. In this paper, I described the outline and summarized results of recent randomized controlled study carried out by Japan Cancer Chemotherapy Study Group for Colorectal Carcinoma and discussed various problems (case registration, ineligible cases, statistical method, follow up) of this study.