Frozen section examination may facilitate reconstructive surgery for mid and low rectal cancer

Background: Distal margin >1 cm provides an oncologic safety in low-lying rectal cancers. We evaluated the accuracy of frozen section (FS) examination in estimating distal margins, and its impact on intraoperative decision making regarding restorative proctectomy.

Methods: Retrospective study of patients who underwent surgery for adenocarcinoma of the mid or lower rectum during 2001.2010 and for whom a distal margin specimen was examined intraoperatively by FS, to confirm microscopically free margins. Intraoperative findings, and frozen and final paraffin section findings were retrieved from patient charts. A distal margin of ≤-1 cm was compared with >1 cm, for free margins at final pathology and local recurrence (LR). The impact of a distal margin ≤-5mm was also assessed. The impact of FS on intraoperative decision making, in patients who did and did not receive preoperative chemoradiotherapy, was assessed.

Results: The mean age of the 63 patients studied was 66.4±11.8 years, and median tumor distance from the anal verge 6 cm(range 1.10 cm). Seven patients underwent abdominoperineal resection, 54 anterior resection, and two Hartman procedures. FS sensitivity and specificity were 83% and 98%, respectively. Accuracy of FS was high for the 41 patients treated with preoperative chemoradiotherapy, and the 22 who were not. Distal margin >5mm at FS examination ensured a free margin at final pathology. LR rate was comparable between patients with distal margin >10mm and ≤-10 mm, 8% vs 11%, P.0.65.

Conclusions: FS examination may help determine free distal margin and consequently, in selected cases, may facilitate a restorative procedure in patients with low rectal cancer.