Comparison of outcomes following intersphincteric resection vs low anterior resection for low rectal cancer: a systematic review

Background. Low Rectal Anterior Resection (LAR) is challenging when anal canal mucosa and/or internal sphincter are involved by very low tumors. In these cases, Intersphincteric resection (ISR) with the removal of the internal sphincter is designed to increase the distal margin of resection, thus preserving the external sphincter and pubo-rectalis muscle complex. Aim is to compare results after ISR with those of LAR, including subgroup analysis of open, laparoscopic and robotic ISR. Methods. Studies published from January 1991 to January 2017 describing ISR and comparing results with LAR in adults were included irrespective of the technique. Tumor and surgical characteristics, clinical, functional and oncological results were collected. Results. 25 non-randomized studies were included. Postoperative mortality ranged between 0% and 2.3%. The hospital stay ranged from 5 days to 40 days, lower in robotic ISR group if compared with laparoscopic ISR. Patients avoiding permanent stoma with ISR accept a lower continence level as satisfactory. Furthermore, anorectal function after ISR often tends to improve. ISR and LAR presented not statistically significant differences. Oncological outcomes were not statistically different Morbidity, blood loss and need for blood transfusions were lower in the laparoscopic ISR if compared with open approach. Conclusions. Morbidity could more frequently affect open ISR if compared with laparoscopic ISR. Functional outcomes were influenced by neoadjuvant CRT, but not by the surgical approach of reconstruction, while were positively influenced by partial ISR with respect to total ISR.