Prognostic significance of the circumferential resection margin following total mesorectal excision for rectal cancer

BACKGROUND: Knowledge of prognostic factors following resection of rectal cancer may be used in the selection of patients for adjuvant therapy. This study examined the prognostic impact of the circumferential resection margin on local recurrence, distant metastasis and survival rates. METHODS: A national population-based rectal cancer registry included all 3319 new patients from November 1993 to August 1997. Some 686 patients underwent total mesorectal excision with a known circumferential margin. This shortest radial resection margin was measured in fixed specimens. None of the patients had adjuvant radiotherapy. RESULTS: Following potentially curative resection and after a median follow-up of 29 (range 14--60) months, the overall local recurrence rate was 7 per cent (46 of 686 patients): 22 per cent among patients with a positive resection margin and 5 per cent in those with a negative margin (margin greater than 1 mm). Forty per cent of patients with a positive margin developed distant metastasis, compared with 12 per cent of those with a negative margin. With decreasing circumferential margin there was an exponential increase in the rates of local recurrence, metastasis and death. CONCLUSION: The circumferential margin has a significant and major prognostic impact on the rates of local recurrence, distant metastasis and survival. Information on circumferential margin is important in the selection of patients for postoperative adjuvant therapy.