 Rectal cancer accounts for 5 of all cancers diagnosed in Canada for both men and women between 1995 and 2004 Public Health agency of Canada _ Health 2004. Preoperative radiotherapy RT, with or without chemotherapy, is an accepted treatment for patients with locally advanced rectal carcinoma followed by surgical resection Bosset and Horiot 2001; Sauer, Fietkau et al. 2003; Birgisson, Talback et al. 2005. The current standard treatment at Princess Margaret Hospital PMH is preoperative pelvic radiation therapy to a total dose of 50 Gy25 fractions5 weeks. The total radiation dose is reduced to 45 Gy25 fractions5 weeks when there is a concern about the volume of small bowel within the treatment volume. Radiation therapy is delivered with 5-fluorouracil 5-FU, 225mgm224h, by protracted venous infusion PVI or oral capecitabine, 825 mgm2 BID for 5 weeks, starting the first day and completing the day of last day of radiation therapy. 