Multicentre study of circumferential margin positivity and outcomes following abdominoperineal excision for rectal cancer

Abstract

Rectal cancer outcomes following abdominoperineal excision (APE) have been inferior to those for anterior resection, including more positive circumferential resection margins (CRMs). An erroneously conservative interpretation of APE (rather than a radical resection termed 'extralevator') has been proposed as the cause. In this multicentre study, factors contributing to CRM positivity were examined following APE according to its original description. Data were collected from five hospital databases up to June 2011 including small- and larger-volume units (3 hospitals had 5 or fewer and 2 hospitals had more than 5 APE procedures per year). Primary outcome measures were CRM status; secondary outcomes were local recurrence and death. Of 327 patients, 302 patients had complete data for analysis. Some 50·0 per cent of patients had neoadjuvant chemoradiotherapy. Histopathological examination showed that 62·9 per cent had tumour category T3 or T4 cancers, 42·1 per cent had node-positive disease and the CRM positivity rate was 13·9 per cent. Multivariable analysis showed only pathological tumour category pT4 (odds ratio 19·92, 95 per cent confidence interval 6·48 to 68·61) and node positivity (odds ratio 3·04, 1·32 to 8·05) to be risk factors for a positive circumferential margin. CRM positivity was a risk factor for local recurrence (P = 0·022) and decreased overall survival (P = 0·001). Hospital volume had no impact on the likelihood of CRM positivity (P = 0·435). In patients undergoing APE by appropriately trained surgeons using a standardized approach, margin positivity was dictated by tumour stage, but not by centre or surgeon.