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

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.

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 ≤5 mm was also assessed. The impact of FS on intraoperative decision making, in patients who did and did not receive preoperative chemoradiotherapy, was assessed.

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 >5 mm at FS examination ensured a free margin at final pathology. LR rate was comparable between patients with distal margin >10 mm and ≤10 mm, 8% vs 11%, P = 0.65.

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