The minimum distal resection margin in rectal cancer surgery and its impact on local recurrence - A retrospective cohort analysis.

Aim: The distal resection margin (DRM) plays a pivotal role in rectal cancer surgery. Colorectal surgeons are often torn between keeping an oncologically safe margin versus aiming at sphincter preserving surgery. This study was performed to assess the oncological safety of a minimal DRM of <1 cm.

Methods: From a prospectively maintained database for rectal cancer 405 patients were identified. Out of 405 patients 88 patients were eligible for the study characterized by UICC tumor stage of II or III, cancer less than 12 cm from the anal verge and a complete course of preoperative chemoradiotherapy (CRT) before undergoing low anterior rectal resection between 2004 and 2012. Preoperative staging included rigid rectoscopy, endo-rectal ultrasound as well as pelvic MRI. Primary endpoints were overall survival (OS) and local recurrence-free survival (LRFS).

Results: The incidence of local recurrence was 5.7% (n = 5). In DRM <1 cm (n = 33) local recurrence was seen in two patients (6.1%) and with DRM ≥ 1 cm (n = 55) in three patients (5.5%). The 5-year OS rate was 94.5% (93.2% DRM <1 cm, 95.7% DRM ≥1 cm; P = 0.642). 5-year LRFS was 93.2% in DRM <1 cm and 95.7% in DRM ≥1 cm (P = 0.936).

Conclusion: R0 resection of stage II and II rectal cancer of the mid and lower third after preoperative CRT yields excellent results even with DRM <1 cm. Minimizing the distal resection margin may allow surgeons to offer sphincter sparing surgery without compromising local recurrence-free and overall survival in individual patients.