The Importance of a Minimal Tumor-Free Resection Margin in Locally Recurrent Rectal Cancer

BACKGROUND: The importance of the circumferential resection margin has been demonstrated in primary rectal cancer, but the role of the minimal tumor-free resection margin in locally recurrent rectal cancer is unknown. OBJECTIVE: The purpose of this work was to evaluate the prognostic importance of a minimal tumor-free resection margin in locally recurrent rectal cancer. DESIGN: This was a single-institution, retrospective study. SETTINGS: This study was conducted in a tertiary referral hospital. PATIENTS: Based on the final pathology report, surgically treated patients with locally recurrent rectal cancer between 1990 and 2013 were divided into 4 groups: 1) tumor-free margins of >2mm, 2) tumor-free margins of >0 to 2mm, 3) microscopically involved margins, and 4) macroscopically involved margins. MAIN OUTCOME MEASURES: Local control and overall survival were the main outcome measures. RESULTS: A total of 174 patients with a median follow-up of 27 months (range, 0-144 months) were eligible for analysis. There was a significant difference in 5-year local re-recurrence-free survival in favor of 41 patients with tumor-free margins of >2mm compared with 34 patients with tumor-free margins of >0 to 2mm (80% vs 62%; p = 0.03) and a significant difference in 5-year overall survival (60% vs 37%; p = 0.01). The 5-year local re-recurrence-free and overall survival rates for 55 patients with microscopically involved margins were 28% and 16%, and for 20 patients with macroscopically involved margins the rates were 0% and 5%. On multivariable analysis, tumor-free margins of >0 to 2mm were independently associated with higher re-recurrence rates (HR, 2.76 (95% CI, 1.06-7.16)) and poorer overall survival (HR, 2.57 (95% CI, 1.27-5.21)) compared with tumor-free margins of >2mm. LIMITATIONS: This study was limited by its retrospective nature. CONCLUSIONS: Resection margin status is an independent prognostic factor for re-recurrence rate and overall survival in surgically treated, locally recurrent rectal cancer. In complete resections, patients with tumor-free resection margins of >0 to 2mm have a higher re-recurrence rate and a poorer overall survival than patients with tumor-free resection margins of >2mm.