Objectives: To evaluate whether postoperative low pelvic radiotherapy (RT) combined with chemotherapy is an appropriate treatment for stage II and III rectal cancer.
Methods: Between November 1997 and May 2006, 104 patients with stage II and III rectal cancer underwent surgery as the primary treatment followed by postoperative RT combined with chemotherapy in our institute and were reviewed retrospectively. Sixty-nine patients received low pelvic RT only (upper margin at 1 cm above the low end of the sacroiliac joint; median dose 54 Gy) (low pelvic RT group) and the other 35 patients received whole pelvic RT (upper margin at the mid L5; median dose 43.2 Gy) and subsequently received a boost to the low pelvis (total median dose 54 Gy) (whole pelvic RT group).
Results: The 5-year overall survival rate, local control rate, and distant metastasis-free rate were 72% versus 63%, 86% versus 84%, and 66% versus 62% for low pelvic versus whole pelvic RT group. There were no statistical differences in these 2 groups. Two patients (2.9%) of the low pelvic RT group and 2 patients (5.7%) of the whole pelvic RT group developed upper pelvis relapse, which was out of the low pelvic field. The incidence of Grade 3 to 5 small bowel late complications of the low pelvic RT group was significantly less than that of the whole pelvic RT group (4.3% vs. 20%) (P=0.029).
Conclusions: Low pelvic RT significantly reduces small bowel late complications and does not compromise the overall survival rate, local control rate, and distant metastasis-free rate.