Close distal margin is associated with locoregional rectal cancer recurrence: A multicenter study.

BACKGROUND AND OBJECTIVES: The importance of the radial margin for rectal cancer resection is well understood. However, surgeons have deemphasized the distal margin, accepting very close distal margins to perform sphincter-preserving surgery. We hypothesized that distal margins < 1 cm would be an independent risk factor for locoregional recurrence. The objective was to determine whether close distal margins are associated with increased locoregional recurrence risk. METHODS: This was a multi-institutional retrospective cohort study conducted at six academic medical centers including patients who received low anterior resection surgery for primary rectal cancer between 2007 and 2018. RESULTS: Of 556 low anterior resection patients, the rate of close distal margin was 12.8% (n = 71), and the locoregional recurrence rate was 5.0% (n = 28). The locoregional recurrence rate for close distal margin cases was 9.9% (n = 7) compared to 4.3% (n = 21) for distal margins ≥1.0 cm. In multivariable analysis, the only factor significantly associated with locoregional recurrence was close distal margin (adjusted odds ratio: 2.80, confidence interval: 1.08-7.25, p = 0.035). CONCLUSIONS: Rectal cancer patients with close distal margins (<1 cm) following low anterior resection had a significantly higher risk for locoregional recurrence. Therefore, the decision to perform low anterior resection with margins < 1 cm should be taken with caution.