Sphincter preservation in rectal cancer with preoperative radiation therapy and coloanal anastomosis: Long term follow-up

Background: To determine if preoperative radiation therapy allows sphincter preservation in the treatment of rectal cancer. Methods: Thirty six patients with the diagnosis of invasive, resectable, primary adenocarcinoma of the rectum limited to the pelvis were enrolled on a Phase I/II trial of preoperative radiation therapy plus low anterior resection/coloanal anastomosis. By preoperative assessment, all patients had invasive tumors (5,T₂; 31,T₃) involving the distal half of the rectum and clinically required an abdominoperineal resection. The median tumor size was 3.8 cm [range: 1.5-7 cm] and the median distance from the anal verge was 4 cm [range: 3-7 cm]. The whole pelvis received 46.80 Gy followed by a 3.60 Gy boost to the primary tumor bed. The median follow-up was 56 months [range: 4- 121 months]. Results: Of the 35 patients who underwent resection, 5 (14%) had a complete pathologic response and 27 (77%) were able to successfully undergo a low anterior resection/coloanal anastomosis. The incidence of local failure was crude: 17% and 5-year actuarial: 21%. The 5-year actuarial survival was 64%. Analysis of sphincter function using a previously published scale was performed at the time of last follow-up in the 27 patients who underwent a low anterior resection/coloanal anastomosis. Function was good or excellent in 85%. The median number of bowel movements/day was 2 (range: 0-8). Conclusions: Our data suggest that preoperative radiation therapy allows sphincter preservation in 77% of selected patients who would otherwise require an abdominoperineal resection, and 85% have good to excellent sphincter function. Given the moderate local failure rate, we now routinely use preoperative combined modality therapy plus postoperative chemotherapy for patients with clinical T₃ disease.