Is a Distal Resection Margin of ≤ 1 cm Safe in Patients with Intermediate- to Low-Lying Rectal Cancer? A Systematic Review and Meta-Analysis

Background It is generally accepted that the distal resection margin of intermediate- to low-lying rectal cancer should be greater than 2 cm and at least 1 cm in special cases. This study intends to investigate whether a distal resection margin <= 1 cm affects tumor outcomes for patients with intermediate- to low-lying rectal cancer. Methods A systematic review of the literature was conducted. Sixteen studies included data for distal resection margins <= 1 cm (1684 cases) and > 1 cm (5877 cases), and 5 studies included survival data. Meta-analysis was used to compare the local recurrence rate and long-term survival of patients with distal resection margins > or <= 1 cm. Results The local recurrence rate in the <= 1-cm margin group (9.5%) was 2.3% higher than that in the > 1-cm margin group (7.2%) according to a fixed-effects model (RR [95% CI] 1.42 [1.18, 1.70], P < 0.001). The overall survival results of the five 1-cm margin studies showed an HR (95% CI) of 0.96 (0.75, 1.24) (P = 0.78). Subgroup analysis showed that the local recurrence rate in the subgroup with perioperative treatment was 1.2% lower in the <= 1-cm margin group (8.3%) than in the > 1-cm margin group (9.5%) (RR [95% CI] 0.97 [0.63, 1.49], P = 0.90). In the surgery alone subgroup, the local recurrence rate was 4.7% higher in the <= 1-cm margin group (12.4%) than in the > 1-cm group (7.7%) (RR [95% CI] 1.76 [1.09, 2.83], P = 0.02). Conclusions For patients with intermediate- to low-lying rectal cancer undergoing surgery alone, a distal resection margin <= 1 cm may be not safe.