Close distal margins do not increase rectal cancer recurrence after sphincter-saving surgery without neoadjuvant therapy.

Purpose: The oncological results of close distal resection margins (DM) have been mixed due to variations in perioperative treatment protocols and surgical expertise. With the increased application of sphincter-saving surgery in the management of rectal cancer, "close shave" DM is an increasingly encountered phenomenon. Our center aims to examine the oncological outcomes of "close shave" DM in the absence of neoadjuvant therapy in the surgical treatment of rectal cancer.

Methods: A prospective database of 320 patients who underwent curative surgical resection for primary rectal cancer between 1999 and 2007 was reviewed. One hundred forty-eight patients had "close shave" DM (DM <1 cm) and 70 (22 %) patients had stage 1, 102 (32 %) patients had stage 2, and 148 (46 %) patients presented with stage 3 disease. Median follow-up was 45 months.

Results: The overall recurrence rate for the entire study cohort was 29 % (n = 94), with 6.6 % of patients developing locoregional recurrence. Recurrence was noted to be significantly associated with decreasing circumferential resection margin (p = 0.008) and increasing American Joint Committee on Cancer stage (p < 0.001). Five-year cancer-specific survival (CSS) for patients with DM <1 cm was 75.6 % and is higher compared to patients with longer DM (p = 0.041). Multivariate analysis showed that CSS was worsened with T stage, N stage, and perineural invasion status. Decreasing DM, however, was not significantly associated with poorer CSS or recurrence rates.

Conclusion: Close distal resection margins do not negatively impact long-term disease control, even without the use of neoadjuvant therapy, provided that safe, optimal surgical resection is performed. Circumferential radial margin may be a more important indicator for outcomes.