Intersphincteric resection with excision of internal anal sphincter for conservative treatment of very low rectal cancer

PURPOSE: Standard surgical treatment for low rectal cancer situated below 5 cm from the anal verge or at less than 1 cm from the anal ring is abdominoperineal resection. This is because of the necessity both to achieve a sufficient distal margin and to preserve the whole of the anal sphincter. The aim of this study was to evaluate morbidity, oncologic, and functional results of intersphincteric resection with excision of the internal anal sphincter and low coloanal anastomosis for carcinomas of the anorectal junction. METHODS: From January 1990 to December 1996, 16 patients were studied prospectively. All patients had an infiltrating adenocarcinoma (5 T2 and 11 T3), located between 2.5 and 4.5 (mean, 3.6) cm from the anal verge. Rectal resection with a minimum distal margin of 2 (mean, 2.4) cm was performed in all cases; six patients underwent partial resection of the internal sphincter, and ten patients had a subtotal resection. A colonic J-pouch was associated with coloanal anastomoses in eight cases. Twelve patients had preoperative radiotherapy, 3 with concomitant chemotherapy; 5 patients had postoperative chemotherapy. RESULTS: There was no postoperative mortality. Morbidity occurred in four patients, of whom two underwent permanent colostomy after pelvic hemorrhage or anovaginal fistula. After a median follow-up of 44 (range, 11-92) months, no local recurrence was observed, and two patients died of distal metastases. The five-year actuarial survival rate was 75 percent. Continence was normal in one-half of patients and was altered in the other patients who suffered from occasional minor leaks. The median resting pressure was lower after subtotal than after partial resection of the internal sphincter (40 vs. 70 cm H2O; P = 0.02), but functional results were similar in the two groups. CONCLUSION: These preliminary results suggest that intersphincteric resection can be an alternative to abdominoperineal resection for selected rectal tumors situated at the anorectal junction, without compromising chance of cure. Functional results and continence were not altered by subtotal resection of the internal anal sphincter.