Adjuvant chemotherapy was unnecessary in pathological stage Ⅱ colorectal cancer following initial treatment of surgery without high risk factors of recurrences. The treatment efficacy of adjuvant chemotherapy for pT1-3N0M0 colorectal cancer following preoperational chemotherapy or chemoradiotherapy remains unclear. Part of clinical local advanced colorectal cancer(cTxN1-2M0), which turn out to be pT0-3N0M0 after preoperational chemotherapy or chemoradiotherapy, might not really need adjuvant chemotherapy due to the down-stage efficacy of the preoperational treatments, or the misleading by lymph nodes false-positive imaging diagnosis.