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Chen et al. Mini-invasive Surg 2018;2:43 I http://dx.doi.org/10.20517/2574-1225.2018.42 Page 3 of 12

or a fluoropyrimidine-based regimen was prescribed. Long-course radiotherapy (total of 5000 cGy in 25
fractions) was concurrently administered. The median time interval between radiotherapy completion and
robotic surgery was 91 (range, 47-363) days.

We thoroughly evaluated the surgical outcomes, including the operation time (with operation, console,
and docking times), blood loss, complication rates, and pathologic clearance, including the positive cir-
cumferential resection margin (CRM) and distal resection margin (DRM) rates. Docking time was defined
as the time taken to position the robot and mount the robotic arms. Postoperative follow-up studies in-
cluded physical examination and serum CEA assay every 3 months for the first 2 years and thereafter every
6 months. Chest radiograph was taken every 6 months and abdominopelvic CT was taken annually in the
following years. Colonoscopy was performed annually.

Surgical procedure
[15]
The single-docking technique with five or six ports was used as the docking method . The da Vinci® Si
Surgical System was docked over the left flank of the patient. The second arm was engaged at the right
upper trocar, and the first and third arms worked at the left medial and lateral trocars, respectively
[Figure 1A and B]. An assistant on the right side of the patient used one or two ports for suctioning and
additional retraction. High dissection and low ligation of the inferior mesenteric vessel and mobilization
[16]
of the left colon was done but splenic flexure was not taken down regularly . The inferior mesenteric
vein was also identified but was not ligated immediately. The intraoperative view of robotic-assisted total
mesorectal excision compared with laparoscopic total mesorectal excision showed more clear obviously
[Figure 1C and D]. Complete robotic-assisted TME with single-docking technique was performed in all
patients.

After complete mobilization of the sigmoid or descending colon, mesocolon, and entire rectum after TME,
low anterior resection (LAR) with the double-staple technique, intersphincteric resection (ISR) with colo-
anal anastomosis [Figure 1E and F] and loop colostomy, or abdominoperineal resection was accordingly
[16]
performed . For the ISR of the perineal part, we used the Lone Star Retractor System® to assist operation.
The specimen was then extracted and resected transanally (natural orifice specimen extraction, Figure 1G).
Coloanal anastomosis was performed using the hand-sewn method. A loop colostomy of the transverse
colon was created. A drain tube was placed into the pelvic cavity through laparoscopic assistance.

Statistical analysis
All data were statistically analyzed using SPSS Version 19.0 (SPSS Inc., Chicago, IL, USA). All patients were
followed up until their death, last follow-up, or 30 April 2017. The operation time was defined as the time
between the initial skin incision and wound closure completion. A P value of < 0.05 denoted statistical
significance. Overall survival was defined as the time from surgery to death or to the last date the patient
was known to be alive. Disease-free survival was defined as the time from surgery to recurrence of cancer
or to the last date the patient was known to be disease free. Overall survival and disease-free survival were
obtained using the Kaplan-Meier method.

RESULTS
Patients’ characteristics and perioperative outcomes
Of the enrolled patients, 36 were men and 24 were women. The median age was 62 years (range, 24-92).
Forty-nine (81.7%) patients had neoadjuvant chemoradiotherapy. The details of patient characteristics are
presented in Table 1.

The most frequent surgical procedure performed was ISR (37/60, 61.7%). ISR with coloanal anastomosis
was performed in 37 patients, and abdominoperineal resection was performed in 4 patients. Protective di-