Prognostic Impact of Circumferential Resection Margin in Rectal Cancer Treated with Preoperative Chemoradiotherapy

Background. The circumferential resection margin (CRM) is a strong prognostic factor in rectal cancer. The purpose of this study was to investigate the relationship between CRM distance and recurrence in patients with locally advanced rectal cancer who received preoperative chemoradiotherapy (CRT). Methods. We analyzed data for 561 patients who underwent preoperative CRT and curative surgery for locally advanced rectal cancer between August 2001 and December 2008. CRM was divided into four groups: group 1, CRM > 2 mm; group 2, 1.1-2.0 mm; group 3, 0.1-1.0 mm; and group 4, 0 mm. We assessed the associations of CRM with local recurrence and disease-free survival. Results. Groups 1, 2, 3, and 4 comprised 487, 36, 20, and 18 patients, respectively. The local recurrence rate was highest and the disease-free survival rate was lowest in group 4, followed by groups 3, 2, and 1. Survival was similar between groups 2 and 1. Local recurrence rates were lower in groups 3, 2, and 1 than in group 4 [hazard ratio (HR) 0.28, 95 % confidence interval (CI) 0.09-0.91, P = 0.035; HR 0.11, 95 % CI 0.03-0.46, P = 0.002; HR 0.18, 95 % CI 0.08-0.42, P < 0.0001, respectively]. Disease-free survival rates were higher in groups 3, 2, and 1 than in group 4 (HR 0.32, 95 % CI 0.13-0.75, P = 0.009; HR 0.24, 95 % CI 0.10-0.54, P = 0.001; HR 0.26, 95 % CI 0.14-0.48, P < 0.0001, respectively). Conclusions. After preoperative CRT, CRM distance provides useful information for risk stratification in the recurrence of rectal cancer.