[Comparison of oncology outcomes and anal function among laparoscopic partial, subtotal and total intersphincteric resection for low rectal cancers].

Objective: To compare the oncology outcomes and anal function among laparoscopic partial, subtotal and total intersphincteric resection(ISR) for low rectal cancers.

Methods: From June 2011 to February 2016, a total of 79 consecutive patients with low rectal cancers underwent laparoscopic ISR with hand-sewn coloanal anastomosis at our department. According to the distal tumor margin, partial ISR (internal sphincter resection at the dentate line) was used to treat tumors with distance <1 cm from the anal sphincter (n=28), subtotal ISR was adopted for the tumors locating between the dentate line and intersphincteric groove (n=34), and total ISR (resection at the dentate line) was applied in the treatment of intra-anal tumors (n=17). Anal function was evaluated by a standardized gastrointestinal questionnaire, Wexner incontinence score and Kirwan's classification. Metaphase oncological results and postoperative anal function were compared among three groups, and.

Results: Other than the distance of tumor low margin to dentate line (P=0.000) and serum CEA level (P=0.040), no significant differences were noted in baseline data among 3 groups (all P>0.05). The median follow up was 21(8-61) months. The 3-year disease-free survival rates in laparoscopic partial, subtotal and total ISR groups were 91.1%, 88.9%, 88.2% (P=0.901) and the 3-year local relapse-free survival rates were 91.1%, 72.9%, 80.2%(P=0.658), whose all differences were not significant. Thirty-eight patients who did not receive neoadjuvant chemoradiotherapy and underwent ileostomy closure for at least 24 months completed the evaluation of anal function, including 14 cases in partial group, 15 cases in subtotal group and 9 cases in total group. Of 38 patients, 73.7%(28/38) was classified as good function (Wexner incontinence score ≤10) and no patient adopted a colostomy because of severe fecal incontinence(Kirwan classification=grade 5). Furthermore, there were no significant differences in Wexner incontinence score and Kirwan classification among 3 groups (all P>0.05). However, patients with chronic anastomotic stoma stenosis showed worse anal function than those without stenosis [Wexner incontinence score: 18(9-20) vs 6(0-18), P=0.000; Kirwan grading: 3(2-4) vs. 2(1-4), P=0.002].

Conclusions: As the ultimate sphincter-saving technique, laparoscopic ISR can result in better oncologic outcomes and better anal function for patients with low rectal cancers. The different procedures of ISR may not affect the efficacy, but chronic anastomotic stoma stenosis deteriorates incontinence status.