Rectal Cancer, Adjuvant Chemotherapy, FOLFOX(5-fluorouracil/Leucovorin/Oxaliplatin), Total Mesorectal Excision

The introduction of total mesorectal excision (TME) and the progress of neoadjuvant chemoradiotherapy has significantly reduced the risk of local recurrence in locally advanced rectal cancer. However, systemic recurrence rate is not being improved and that is considered as the cause of unsatisfactory overall survival of patients with rectal cancer. Relatively higher systemic relapse rate than local recurrence rate is probably due to the insufficient control of systemic micrometastasis during adjuvant chemotherapy. The efficacy of adjuvant combination cytotoxic chemotherapy after surgery in treatment of rectal cancer remains controversial. In addition, preoperative radiotherapy increases surgical complication such as anastomosis site leakage and radiotherapy itself worsen sexual and urinary function and bowel habit which result in aggravation of the quality of life. Furthermore the preoperative chemoradiotherapy upto 3 months not only extends treatment period but increases cost of care. To reduce the possibility of overtreatment, it is needed to confirm that the preoperative chemoradiotherapy is absolutely necessary to locally advanced rectal cancer patients with safe circumferential margin (CRM) resected curatively by standardized TME operation. In this study, investigators aim to evaluate the efficacy of adjuvant FOLFOX chemotherapy after TME without preoperative chemoradiotherapy in patients with locally advanced rectal cancer having spared CRM are not inferior to that of current standard treatment.