The purpose of adjuvant chemotherapy for patients with colorectal cancer treated with curative surgery is to prevent from metachronous recurrences and to improve their prognosis. Because surgical outcomes in Japan are relatively better compared to those in western countries, optimal and personalized treatment based on evidence introduced not only by other countries but by Japan should be chosen. We now focus on a research of identification of biomarker which predict high risk of recurrence in Stage II colorectal cancer.