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.