Novel anal sphincter saving procedure with partial excision of levator-ani muscle in rectal cancer invading ipsilateral pelvic floor

Purpose Tumors at the level of the anorectal junction had required total levator-ani muscle excision to achieve an adequate resection margin. However, in the cases of tumor invading ipsilateral levator-ani muscle and intact external sphincter, en bloc resection of rectum with levator-ani muscle including tumor would be possible. This hemilevator excision (HLE) technique enables preserving the anal sphincter function while obtaining oncologic clearance and avoiding permanent colostomy in those patients. This study aimed to evaluate the surgical outcomes and feasibility of HLE. Methods Data on 13 consecutive patients who underwent HLE for pathologically proven low rectal cancer were retrospectively collected. All 13 patients presented low rectal cancer at the anorectal ring level that was suspected to invade or abut to the ipsilateral side of the levator-ani muscle. Results A secure resection margin was achieved in all cases, and anastomotic leakage occurred in 2 patients. During follow-up, 3 patients experienced tumor recurrence (2 systemic and 1 local). Among 6 patients who underwent diverting ileostomy closure after the index operation, 2 complained of fecal incontinence. The other 4 patients without fecal incontinence showed <10 times of bowel movement per day. Accessing their incontinence scale, mean Wexner score was 9.4. Conclusion HLE is a novel sphincter-preserving technique that can be a treatment option for low rectal cancer invading ipsilateral levator-ani muscle, which has been an indication for abdominoperineal resection (APR) or extralevator APR. However, the long-term oncologic and functional outcomes of this procedure still need to be assessed to confirm its validity.