Oncological results in rectal cancer patients with a subcentimetre distal margin after laparoscopic‐assisted sphincter‐preserving surgery

BACKGROUND: Distal resection margin (DRM) is closely associated with sphincter‐preserving surgery and oncological safety for patients with mid‐low rectal cancers. However, the optimal DRM has not been determined. METHODS: Data of 378 rectal cancer patients who underwent laparoscopic‐assisted sphincter‐preserving surgery from 2009 to 2015 were retrospectively analysed. Patients were divided into two groups based on DRM: ≤1 cm (n = 74) and >1 cm (n = 304). To minimize the differences between the two groups, propensity‐score matching on baseline features was performed. RESULTS: Before propensity‐score matching, no significant differences in 5‐year disease‐free survival (DFS) (92.8% versus 81.3%, P = 0.128) and 5‐year overall survival (OS) (83.7% versus 82.2%, P = 0.892) were observed in patients with DRMs of ≤1 cm (n = 74) and >1 cm (n = 304), respectively. After propensity‐score matching (1:1), there were also no significant differences in DFS (88.1% versus 78.2%, P = 0.162) and OS (84.5% versus 84.9%, P = 0.420) between the DRM of ≤1 cm group (n = 65) and >1 cm group (n = 65), respectively. A total of 44 patients received preoperative chemoradiotherapy (CRT). In this cohort, the 5‐year local recurrence (LR) rates (P = 0.118) and the 5‐year DFS rates (P = 0.298) were not significantly different between the two groups. A total of 334 patients received surgery without neoadjuvant CRT. There were also no significant differences in the 5‐year LR rates (P = 0.150) and 5‐year DFS rates (P = 0.172) between the two groups. CONCLUSIONS: When aiming to achieve at least a 1–2 cm distal clinical resection margin, a histological resection margin of <1 cm on the DRM gave equivalent clinical outcomes to a DRM of >1 cm.