Long-term oncological outcomes of the sphincter preserving total mesorectal excision with varying distal resection margins.

ABSTRACT

INTRODUCTION: A subcentimeter distal resection margin (DRM) appears to be acceptable for most patients, however, long-term follow up and specific subsets where DRM would influence recurrences have not been adequately investigated. METHODS: A retrospective analysis of all sphincter-preserving resections for mid and low rectal cancers between July 2011 and May 2015 was performed. Extended total mesorectal excisions (TME) and patients with positive pathologic circumferential margins (CRM) were excluded. RESULTS: Two hundred and thirty-six patients fit the inclusion criteria. DRM > 20 mm was obtained in 117 patients (49.6%), between 10 and 20 mm in 78 (33%) and <10 mm in 41 (17.4%) patients. Pathological DRM was positive in 4 patients (1.7%). Sixty-five recurrences occurred at a median follow up of 78.5 months. DRM did not influence any of the oncological outcomes. In a subset analysis of patients with poor pathological response to neoadjuvant radiation, that is, tumor regression grade > 3, DRM influenced disease-free survival (DFS) but not overall survival with a hazard ratio of 4.4 (p = 0.02). This was confirmed on multivariate regression analysis in this subgroup as well where pathological nodal status and DRM < 10 mm were independent predictors of DFS. CONCLUSIONS: A subcentimeter DRM may be acceptable in most patients except those who have an inadequate response to neoadjuvant radiation.