[Analysis on the technical characteristics and clinical efficacy of robotic-assisted intersphincteric resection for...

Objective: To explore the technical characteristics and short-term clinical efficacy of robotic-assisted intersphincteric resection (ISR) for patients with low rectal cancer. Methods: A retrospective cohort study was used. Inclusion criteria: (1) rigid colonoscopy showed lower margin of the tumor ≤5 cm from the anal verge; (2) preoperative rectal MRI or endorectal ultrasound revealed staging T1-2, or T3 patients receiving concurrent chemoradiotherapy; (3) patients less than 70 years old with good function of anal sphincter before surgery; (4) no synchronous multiple primary carcinoma, and no distant metastasis; (5) the method of operation was agreed by the patient. Exclusion criteria: (1) T4 stage tumors; (2) sphincter dysfunction before operation; (3) recurrent tumors; (4) lower edge of tumors beyond the dentate line; (5) death due to non-rectal cancer during follow-up and unsatisfactory follow-up data. The clinical data of 21 patients with low rectal cancer meeting inclusion criteria undergoing robotic-assisted ISR at our department from January 2015 to June 2018 were collected. Parameters during and after operation were observed. Anorectal manometry was performed at 3, 6, and 12 months after the operation, and anal function was evaluated at 3, 6, and 12 months after the closure of the stoma by Kirwan classification and Wexner fecal incontinence score. The key steps of the operation are as follows: according to the principle of total mesorectal excision, the robot continued to enter into the levator ani hiatusdistally, and dissectin the sphincter space; according to the scope of sphincter resection, ISRwas divided into partial ISR, subtotal ISR, and total ISR; subtotal and total ISR usually needed to be combined with transanal pathway. The reconstruction of digestive tract was performed by double stapler anastomosis under laparoscope orhand-sewnanastomosis under direct vision, and preventive ileostomy was completed in the right lower abdomen. Results: Of 21 patients, 13 were male and 8 were female with mean age of (57.5±16.3) years. All the patients successfully completed the operation without conversion to laparotomy. Fourteen cases (66.7%) adopted partial ISR through complete transabdominal approach, 6 cases (28.6%) adopted the subtotal ISR through combined transabdominal and transanal approachs, and 1 case (4.8%) adopted the total ISR through the combined transabdominal and transanal approachs. The total operation time was (213.1±56.3) minutes, including (27.3±5.4) minutes for mechanical arm installation and (175.7±51.6) minutes for robotic operation. The amount of intraoperative hemorrhage was (62.8±23.2) ml, and no blood transfusion was performed in any patient. All patients underwent prophylactic ileostomy, and the stoma was closed 3-6 months after the operation. Except one case of anastomotic leakage, all other stomas were closed successfully. The postoperative hospitalization time was (7.6±2.2) days, and time to fluid intake was (3.3±0.9) days. One case of anastomotic leakage, one case of anastomotic stenosis, one case of inflammatory external hemorrhoids and one case of urinary retention occurred after surgery,and all of them were cured by conservative treatment. The mean diameter of tumors was (2.9±1.2) cm, and the number of harvested lymph node was 12.8 ± 3.3. In the whole group, the circumcision margin was negative, the proximal margin was (12.2 ± 2.1) cm, the distal margin was (1.1 ± 0.4) with all negative, and the R0 resection rate was 100%. The results of anorectal manometry showed that the preoperative rest pressure, rectal maximum squeeze pressure, initial sensory volume and maximum tolerated volume were (45.19±8.46) mmHg, (128.18±18.80) mmHg, (44.33±10.11) ml and (119.00±19.28) ml, respectively;these parameters reduced significantly 3 months after operation and they were (23.44±5.54) mmHg, (93.72±12.15) mmHg, (17.72±5.32) ml and (70.44±10.9) ml, respectively. The differences were statistically significant (all P<0.001). The resting pressure and the rectal maximum squeeze pressure returned to preoperative levels 12 months after operation, which were (39.33±6.64) mmHg and (120.58±16.47) mmHg, respectively (both P>0.05), while the initial sensory volume and the maximum tolerated volume failed to reach the preoperative state, which were (30.67±7.45) ml and (92.25±10.32) ml, respectively (both P<0.05). The patients were followed up for (22.1±10.6) months without local recurrence and distant metastasis. Eighteen patients were evaluated for anal function: Kirwan classification was grade I for 6 cases, grade II for 7 cases, grade III for 4 cases, and grade IV for 1 case; Wexner incontinence score was 8.6±0.8; 14 cases had good defecation control. Conclusion: The clinical efficacy of ISR with Da Vinci robot in the treatment of low rectal cancer is satisfactory.