Effect of the circumferential resection margin on survival following rectal cancer surgery

Background: The aim was to determine the effect of the circumferential resection margin (CRM) on overall survival following surgical excision of rectal cancer. Methods: The effect of CRM on survival was examined by case mix‐adjusted analysis of patients undergoing potentially curative excision of a rectal cancer between 1998 and 2002. Results: Of 1896 patients, 1561 (82·3 per cent) had recorded data on the CRM. In 232 patients (14·9 per cent) tumour was found 1 mm or less from the CRM. In 370 patients (23·7 per cent) it was over 1 mm but no more than 5 mm from the CRM, and in 288 (18·4 per cent) it was over 5 mm but no more than 10 mm from the CRM. The remaining 671 patients (43·0 per cent) had a CRM exceeding 10 mm. Overall 5‐year survival rates for these groups were 43·2, 51·7, 66·6 and 66·0 per cent respectively. Compared with patients with a CRM exceeding 10 mm, the adjusted risk of death was significantly increased for patients with a CRM of 1 mm or less (hazard ratio (HR) 1·61, P < 0·001) and those with a margin greater than 1 mm but no larger than 5 mm (HR 1·35, P = 0·005). There was no added risk for patients with tumour more than 5 mm but 10 mm or less from the CRM (HR 1·02, P = 0·873). The adverse effect of a CRM greater than 1 mm but no larger than 5 mm was found particularly in mid‐rectal cancers. Conclusion: A predicted CRM of 5 mm or less on preoperative staging should be considered for neoadjuvant treatment. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. Defines risk by radial margin