Fecal continence following partial resection of the anal canal in distal rectal cancer: long-term results after coloanal anastomoses.

BACKGROUND The aim of the study was to assess the influence of partial excision of the superior portion of the anal canal (AC) when necessary for tumor margin clearance in distal rectal cancer on fecal continence after coloanal anastomoses. METHODS Between 1977 to 1993, 209 patients with middle and lower third rectal cancers underwent complete rectal excision and coloanal anastomoses. For very low tumors, located at or below 5 cm from the anal verge (AV), varying portions of the superior segment of the AC were excised for tumor margin clearance. The magnitude of resections was inversely proportional to the height of the anastomosis from the AV. The patients were categorized into 3 groups according to their level of anastomoses from AV: group 1, patients with anastomoses from 0.5 to less than 2 cm from AV (1 to 2.5 cm of AC resected, i.e., major resection); group 2, anastomoses at 2 to less than 3 cm from AV (less than 1 cm of AC resected, i.e., minor resection); group 3, with anastomoses at 3 to 3.5 cm from AV (AC completely preserved). A standard questionnaire, physical examination, and anal manometry at intervals of 3, 6, 12, 24, 36, and 48 months were performed prospectively to assess anal continence. RESULTS The patients in the 3 categories were matched for age, gender, stage, presence or absence of a colonic J-pouch, preoperative neoadjuvant radiotherapy and surgical technique. Fourteen patients with postoperative radiotherapy were excluded from the clinical assessment. Mean follow-up was 33.5 months. There were 43 patients in group 1, 75 in group 2, and 73 in group 3 for clinical assessment. In the first year, there was progressive improvement in anal continence in all 3 groups. At 2 years, 50% in group 1, 73% in group 2, and 62% in group 3 were fully continent. The proportion of patients fully continent in group 1 remained unchanged as compared to continued improvement for groups 2 and 3 following the first year. At 4 years, 50% in group 1, 80% in group 2, and 68% in group 3 were completely continent. The difference among the 3 groups was not statistically significant. CONCLUSIONS For distal rectal cancer, where tumor margin clearance necessitates partial resection of the superior portion of the AC, when limited to less than 1 cm, the proportion of patients remaining fully continent is similar to those with complete AC preservation. More substantial excisions of the AC can still result in satisfactory anal continence, such that following the fourth year, one half of the patients can expect to be fully continent.