Intersphincteric Resection Has Similar Long-term Oncologic Outcomes Compared With Abdominoperineal Resection for Low Rectal Cancer Without Preoperative Therapy: Results of Propensity Score Analyses

Abstract

Intersphincteric resection has been performed for very low rectal cancer in place of abdominoperineal resection to avoid permanent colostomy. This study aimed to evaluate long-term oncologic outcomes of intersphincteric resection compared with abdominoperineal resection. In this retrospective study, propensity score matching and stratification analyses were performed to reduce the effects of confounding factors between groups, including age, sex, BMI, CEA value, tumor height, tumor depth, lymph node enlargement, and circumferential resection margin measured by MRI. A database maintained at our institute was used to identify patients during the period between 2000 and 2014. A total of 285 patients who underwent curative intersphincteric resection (n = 112) or abdominoperineal resection (n = 173) for stage I to III low rectal cancer without preoperative chemoradiotherapy were enrolled in this study. The main outcome was recurrence-free survival. Patients in the abdominoperineal resection group were more likely to have a preoperative diagnosis of advanced cancer before case matching. After case matching, clinical outcomes were similar between intersphincteric resection and abdominoperineal resection groups. Five-year relapse-free survival rates were 69.9% for the intersphincteric resection group and 67.9% for abdominoperineal resection group (p = 0.64), and were similar in the propensity score-matched cohorts (89 matched pairs). Three-year cumulative local recurrence rates were 7.3% for intersphincteric resection and 3.9% for abdominoperineal resection (p = 0.13). In the propensity score-matched model, the hazard ratio for recurrence after intersphincteric resection in comparison with abdominoperineal resection was 0.90. Stratification analysis revealed similar recurrence rates (HR, 0.75-1.68) for intersphincteric resection in comparison with abdominoperineal resection. Eight covariates were incorporated into the model, but other covariates were not included. Our findings suggest similar oncologic outcomes for intersphincteric resection and abdominoperineal resection without preoperative chemoradiotherapy in patients with low rectal cancer adjusted for background variables. See Video Abstract at http://links.lww.com/DCR/A661.