Circumferential resection margin as a prognostic factor in rectal cancer

Background: This study examined the prognostic impact of the circumferential resection margin (CRM) in patients with rectal cancer treated by total mesorectal excision (TME) with or without radiotherapy. Methods: A national population-based rectal cancer registry included 3196 patients with known CRM status between 1993 and 2004. Some 90.5 per cent of the patients had surgery alone and 9.5 per cent had preoperative radiotherapy. Patients who did not have TIME, those in whom the CRM was not measured, patients with intraoperative bowel or tumour perforation and those who received postoperative radiotherapy were excluded. Results: Five-year local recurrence, distant metastasis and overall survival rates were 23.7, 43.9 and 44.5 per cent respectively for patients with a CRM of 0-2 mm, compared with 8.9, 21.7 and 66.7 per cent respectively for those with wider margins. A CRM of 2 mm or less had all impact on the prognosis of T2 and T3 tumours located 6-15 cm. above the anal verge, but not on lower rumours. CRM also had a prognostic impact on the three endpoints in patients who received preoperative radiotherapy, but with less precision. Conclusion: A CRM of 2 mm or less confers a poorer prognosis and patients should be considered for neoadjuvant treatment.