Background: Over the past several years, preoperative chemoradiotherapy (CRT) has contributed remarkably to make more sphincter-preserving procedure (SPP) possible for lower rectal cancer. The aim of this study was to compare the outcomes between abdominoperineal resection (APR) and SPP after preoperative CRT in patients with locally advanced lower rectal cancer. Methods: A retrospective investigation was conducted with a total of 122 patients who underwent radical surgery combined with preoperative CRT for locally advanced lower rectal cancer. Of these, 50 patients underwent APR and 72 received SPP. Surgery was performed 6-8 weeks after completion of preoperative CRT. Oncologic outcomes were compared between the two groups, and the clinicopathologic factors affecting the treatment outcomes were evaluated. Results: Circumferential resection margin (CRM) involvement (P = 0.037) and postoperative complication rate (P = 0.032) were significantly different between APR and SPP. Patients who underwent APR had a higher 5-year local recurrence (22.0% vs. 11.5%, P = 0.028) and lower 5-year cancer-specific survival (52.9% vs. 71.1%, P = 0.03) rate than those who underwent SPP. Pathologic N stage was the most critical predictor for local recurrence and survival. Conclusions: Our study shows that APR following preoperative CRT exhibited more adverse oncologic outcomes compared with SPP. This result may be due to higher rates of CRM involvement in APR even with preoperative CRT. We suggest that sharp perineal dissection and wider cylindrical excision at the level of the anorectal junction are required to avoid CRM involvement and improve oncologic outcomes in patients who undergo APR following preoperative CRT.
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