Distal bowel surgical margin shorter than 1 cm after preoperative radiation for rectal cancer: is it safe?

Abstract

The primary end-point of our randomized trial was sphincter preservation. The secondary aim was to evaluate whether distal bowel clearance < or =1 cm is safe after radiation. The study randomized 312 patients with cT3-4 resectable low-lying and mid-rectal cancer to receive either preoperative irradiation (5 x 5 Gy) with immediate total mesorectal excision (TME) or chemoradiation (50.4 Gy, bolus 5-fluorouracil and leucovorin) with delayed TME. After anterior resection, pathologists prospectively measured macroscopic and microscopic distal bowel clearance. Macroscopic and microscopic distal bowel clearance, distal intramural spread, sphincter preservation, local control, disease-free survival, and overall survival did not differ in the two randomized groups. Pooled analysis of the two groups showed that the incidence of local recurrence at 4 years (median follow-up) for patients with macroscopic clearance < or =1 cm (n = 42) and >1 cm (n = 124) was 11.3% and 15.4%, respectively (P = 0.514); the hazard ratio (HR) was 0.70, and the 95% confidence interval (CI) was 0.23-2.07. The corresponding values for patients with microscopic clearance < or =1 cm (n = 51) and >1 cm (n = 101) were 9.6% and 17.6% (P = 0.220; HR 0.51; 95% CI 0.17-1.53). After preoperative radiotherapy, distal bowel clearance < or =1 cm did not compromise local control.