Background Locally advanced rectal carcinoma continues to be a major oncologic problem in the United States. Several landmark studies have led to the current standard approach to the care of patients with stage II and III rectal cancer. In 1990 adjuvant 5- fluorouracil based chemoradiation became the accepted standard of care on the basis of two randomized trials. During the following two decades significant modifications were made to both the administration of chemoradiation therapy and surgery. First, continuous infusion 5-fluorouracil daily concurrent with radiation to was shown to be superior to bolus 5-fluorouracil for 3 consecutive days during weeks 1 and 5 of radiation. The overall rate of tumor relapse fell from 47% to 37%, and distant metastasis rate fell from 40% to 31%. Notably, local tumor recurrence was not significantly different between the two chemotherapy schedules. The improvement in relapse rate translated into a 4 year survival benefit, 70% versus 60%, favoring the protracted venous infusion of 5-fluorouracil (5-FU).