Clinicopathological analysis of distal margin for rectal cancer after preoperative chemoradiation therapy.

BACKGROUND/AIMS: Preoperative chemoradiation therapy (CRT) for advanced rectal cancer allows anal sphincter preservation in some patients who would require an abdominoperineal resection. But adequate distal margin in patients with locally advanced rectal cancer requiring preoperative CRT is unclear. The objective was to evaluate necessary distal margin from reduced tumor by preoperative CRT for anal sphincter preservation.

METHODOLOGY: This study included 11 consecutive patients who performed low anterior resection and abdominoperineal resection for rectal cancer after preoperative CRT. Distal margin length from reduced tumor by preoperative CRT to residual viable cancer, tumor grade, lymph-node-metastasis stage and pathological changes of tumors were examined.

RESULTS: Length from anal side edge of reduced tumor by preoperative CRT to pathological residual tumor ranged from +6 mm to -9 mm. Tumor stages were as follows: T0-2, N0, M0=3, T3, N0, M0=5, T4, N0, M0=1 and T3, N0, M+1=2. Median follow-up was 19 months. Recurrence occurred in one patient and was distant and not local. Pathological examinations showed that no patient had lymph-node-metastasis and residual tumors by preoperative CRT.

CONCLUSIONS: This study suggests that for patients with locally advanced rectal cancer undergoing resection and preoperative CRT, distal margins ≥1 cm from reduced tumor by preoperative CRT seem to compromise pathological outcome.