Acceptance of a 5-mm distal bowel resection margin for rectal cancer: is it safe?

Aim Acceptance of a short distal bowel margin results in a higher rate of anterior resection but may compromise oncological safety. This study aimed to evaluate the safety of a 5-mm distal margin. Method A retrospective analysis was carried out of 412 consecutive patients with rectal cancer treated with anterior resection with a negative circumferential resection margin. Radiotherapy was given to 63% of patients with an advanced tumour. The median follow up was 75 months. Results Fewer patients in the group with a distal margin of <= 5 mm had a tumour with an advanced pT stage compared to patients in the group with a distal margin of > 5 mm (P = 0.033). Two patients were converted to abdominoperineal resection because of a positive 'doughnut', leaving 410 patients, in whom 5.4% (95% CI, 0-11.3%) of the group with a distal margin of <= 5 mm had local recurrence at 5 years compared with 4.2% (95% CI, 2.1-6.3%) of the group with a distal margin of > 5 mm ( P = 0.726). The corresponding figures for the 5-year overall survival were 82.4% ( 95% CI, 72.6-92.2%) vs 76.3% ( 95% CI, 71.8-80.8%) ( P = 0.581). All four anastomotic recurrences occurred in the group with a distal margin of > 5 mm. Conclusion A distal margin of <= 5 mm did not compromise oncological safety in patients undergoing preoperative radiation for an advanced rectal cancer.