Purpose: Negative surgical margins are important for local control of rectal cancer treated with sphincter-preserving surgery. However, the association of rectal cancer recurrence with close distal margin is not well established.
Methods: Data were extracted from a prospective database of patients collected between 1991 and 2003. Included were 627 patients who underwent curative low anterior resection with total mesorectal excision for rectal cancer 2 to 12 cm from the anal verge. Three hundred ninety-nine patients received neoadjuvant therapy, 65 received postoperative adjuvant therapy alone, and 163 were treated with surgery alone. Median follow-up was 5.8 years.
Results: On multivariable analysis, overall recurrence was associated with pathologic stage, lymphovascular invasion, and distal margin. Mucosal recurrence was uncommon; only 16 events were recorded, and of those only 8 were at the initial site of isolated tumor recurrence; 7 of the 8 were surgically salvaged. On univariable analysis, mucosal recurrence was associated with close distal margin (5 vs 2% at 5 y) and lymphovascular invasion (7 vs 2%). Pelvic recurrence, other than isolated mucosal recurrence, was associated with distal location (6 vs 4% at 5 y) and lymphovascular invasion (11 vs 4%). Distal margin as a continuous variable was associated with overall recurrence (excluding isolated mucosal recurrence).
Conclusions: Close distal resection margin identifies patients with increased risk of mucosal and overall cancer recurrence. Although neither causality nor a minimally acceptable margin length can be defined, the data support the importance of achieving a clear distal resection margin in the surgical management of rectal cancer.