A Circumferential Resection Margin of 1 mm Is a Negative Prognostic Factor in Rectal Cancer Patients With and Without Neoadjuvant Chemoradiotherapy

BACKGROUND: There is ongoing debate about the appropriate criterion for defining a positive circumferential resection margin after radical surgery for rectal cancer. OBJECTIVE: The purpose of this work was to determine the importance of the extent of the circumferential resection margin with regard to outcomes in patients with rectal cancer who underwent total mesorectal excision with and without neoadjuvant chemoradiotherapy. DESIGN: This was a retrospective review of prospectively collected data. SETTINGS: The study was conducted in a tertiary care hospital. PATIENTS: We reviewed the medical charts of 780 patients with rectal cancer who underwent radical surgery from 2004 to 2009. There were 599 patients (76.8%) who did not receive neoadjuvant chemoradiotherapy and 181 patients (23.2%) who did. MAIN OUTCOME MEASURES: The relationship between the extent of the circumferential resection margin (0.5, 1.0, 2.0, and 3.0 mm) and recurrence and survival was assessed. RESULTS: Among circumferential resection margins ≤0.5, ≤1.0, ≤2.0, and ≤3.0 mm, the HR was highest and disease-free survival was longest for a circumferential resection margin ≤1 mm in both the chemoradiotherapy and nonchemoradiotherapy groups. A circumferential resection margin ≤1 mm, lymphatic invasion, histology, pathologic T category, pathologic N category, preoperative CEA, and adjuvant chemotherapy were independent predictors of disease-free survival in the nonchemoradiotherapy group. In the chemoradiotherapy group, a circumferential resection margin ≤1 mm and histology were independent predictors of disease-free survival. Multivariate analysis revealed that a circumferential resection margin ≤1 mm was an independent prognostic factor for overall survival in both of the 2 groups. LIMITATIONS: This was a single-institution, retrospective study. CONCLUSIONS: A circumferential resection margin of ≤1 mm had a strong association with disease-free survival compared with circumferential resection margins ≤0.5, ≤2.0, and ≤3 mm. A circumferential resection margin ≤1 mm was an independent predictor of a poor outcome in both the nonchemoradiotherapy and chemoradiotherapy groups.