Significance of Radial Margin in Patients Undergoing Complete Mesocolic Excision for Colon Cancer

Background: Comparable to circumferential resection margin in rectal cancer, radial margin is a potential prognostic factor in colon cancer that has just begun to be studied. No previous studies have investigated the influence of radial margin in the context of complete mesocolic excision. Objective: This study aimed to examine the impact of radial margin on oncologic outcomes after complete mesocolic excision for colon cancer. Design: We retrospectively reviewed patients with stage I to III colon cancer who underwent curative resection from October 2010 to March 2013. Settings: This study was conducted using the prospective colorectal cancer registry of Severance hospital. Patients: A total of 834 consecutive patients who underwent complete mesocolic excision for colon adenocarcinoma were included. Interventions: We assigned patients into 3 groups according to radial margin distance: group A, radial margin ≥2.0 mm; group B, 1.0 ≤ radial margin < 2.0 mm; group C, radial margin <1 mm. Main Outcomes and Measures: Overall survival and disease-free survival were estimated. Results: On adjusted Cox regression analysis, only group C was predictive of reduced overall survival (HR, 1.90; 95% CI, 1.11-3.25; p = 0.018) and disease-free survival (HR, 1.93; 95% CI, 1.28-2.89; p = 0.001). We thereby defined radial margin threatening as radial margin <1 mm. Postoperative 5-fluorouracil (HR, 0.86; 95% CI, 0.35-2.10; p = 0.743) and FOLFOX (HR, 1.23; 95% CI, 0.57-2.64; p = 0.581) chemotherapy did not affect disease-free survival in patients with radial margin threatening. Limitations: This study has the limitations inherent in all retrospective, single-institution studies. Conclusions: Even with complete mesocolic excision, radial margin <1 mm was an independent predictor of survival and recurrence. This finding suggests that special efforts for obtaining a clear radial margin may be necessary in locally advanced colon cancer.