Risk factors for adverse outcome in patients with rectal cancer treated with an abdominoperineal resection in the total mesorectal excision trial

Objective: This study was performed to identify tumor- and patient-related risk factors for distal rectal cancer in patients treated with an abdominoperineal resection (APR) associated with positive circumferential resection margin (CRM), local recurrence (LR), and overall survival (OS). Background: The introduction of total mesorectal excision (TME) has improved the outcome of patients with rectal cancer. However, survival of patients treated with an APR improved less than of those treated with low anterior resections (LAR). Besides, an APR is associated with a higher LR rate. Methods: Patients were selected from the TME trial, which is a randomized, multicenter trial, studying the effects of preoperative radiotherapy (RT) in 1861 patients. Of the Dutch patients, 455 underwent an APR. Location of the bulk of the tumor was scored with surgery, pathology, or other reports. CRM was available from pathology reports. Result: A positive CRM was found in 29.6% of all patients, 44% for anterior, 21% for lateral, 23% for posterior, and 17% for (semi)circular tumor location (P < 0.0001). In a multivariate analysis, T-stage, N-stage, and tumor location were independent risk factors for CRM. If a (partial) resection of the vaginal wall was performed in women, 47.8% of patients still had a positive CKM. T-stage, N-stage, and CRM were risk factors for LR and age, T-stage, N-stage, CRM, and distance of the inferior tumor margin to the anal verge for OS. Conclusion: Age, T-stage, N-stage, CRM, distance of the tumor to the anal verge, and tumor location were independent risk factors for adverse outcome in patients treated with an APR for low rectal cancer. Anterior location, specifically in women, more often requires downstaging and/or more extended resection to obtain free margins.