Study design and participants
We reviewed the cases of 66 consecutive patients who underwent curative resection of rectal cancer at Juntendo University Hospital between January 2016 and February 2019. This was a retrospective study and was approved by our hospital’s Institutional Review Board, which waived the requirement for patient consent. The following cases were excluded from analysis: emergencies, double cancers, stage Ⅳ cancers, abdominoperineal resections, intersphincteric resections, and lateral lymph node dissections.
We divided the patients into a CLS group and a RALS group before comparing the following factors between those groups: age, gender, body mass index, tumor location, surgical approach (CLS or RALS), surgical procedure, distance of the tumor from the margin of the anus, T factor, stage, postoperative serum CK level, duration of postoperative hospital stay, and postoperative complications.
Operative techniques
Robotic procedure
We used the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA, USA) for the robotic procedure. This system consists of a surgeon’s console, an electronic tower that holds the video equipment, and robotic arms. Patients were placed supine and with their legs apart in a 15°–20° Trendelenburg and 8°–10° right-down position. The robot was docked off the patient’s left thigh. Trocar placement for the da Vinci Si and Xi were as shown in Figure 1 and Figure 2, respectively. A 12 mm trocar was used by inserting da Vinci 8mm port. The left colon was mobilized after dividing the inferior mesenteric artery and vein using clips, and the robotic instrument was sited between the patients’ legs. The rectum was suspended from the assistant’s port, using gauze, and we proceeded according to the principles of total mesorectal excision.
The mesorectum was precisely divided beyond the tumor using both robotic arms. The tumor location was checked by colonoscopy. The rectum was divided using an endoscopic linear stapler or da Vinci stapler, the robotic instrument was disengaged, and the specimen was extracted though the lower umbilical trocar incision, which was enlarged to approximately 4 cm. An anvil head was then inserted in the proximal colon and secured with a purse-string suture. The pneumoperitoneum was restored before a circular stapler was used to create an end-to-end anastomosis.
Laparoscopic procedure
A 12mm trocar was inserted at the umbilicus for a 30° standard laparoscope to be inserted. Another three 5 mm trocars were used in the left lower quadrant, and bilaterally in the mid-abdomen (adjacent the umbilicus) along the midaxillary line. A 12 mm trocar was added to the right lower quadrant to facilitate use of an endoscopic linear stapler. Left colon mobilization was performed in a medial to lateral fashion. The inferior mesenteric artery was divided at its root by an endo-clip, and rectal dissection in the mesorectal plane proceeded using conventional laparoscopic instruments for total mesorectal excision. The mesorectum was divided precisely beyond the tumor with an ultrasonic device, and the rectum itself was divided with an endoscopic linear stapler. Specimen extraction and reconstruction were the same as in the robotic procedure.
Other procedures
Rectal anastomoses were performed with a double stapling technique. Patients operated on by the authors were given the option of CLS or RALS, though the final decision was at the surgeon’s discretion. Temporary ileostomies were also created selectively at the surgeon’s discretion, based on consideration of whether the anastomosis site was below 5 cm from the anal verge, whether the patient used steroids or had diabetes, and whether they had received preoperative neoadjuvant chemotherapy. Finally, preoperative neoadjuvant chemotherapy (e.g., FOLFOX or CAPOX) was performed for rectal cancer graded as cT3, cT4a, cT4b, cN+, and cM0 according to the TNM Classification of Malignant Tumors, ninth edition.
Definitions
Each barium enema for tumor assessment was retrospectively reviewed for rectal cancer. The rectum was divided into upper and lower regions. When the tumor was located between the inferior margin of the second sacral vertebra and the peritoneal reflection, its location was recorded as the upper rectum. When the tumor was located below the peritoneal reflection, its location was recorded as the lower rectum. The staging of all cancers was according to the TNM classification.
Anastomotic leakage was defined clinically by the presence of a pelvic abscess, fecal discharge from the wound and drain, septicemia, and peritonitis, with or without radiologically confirmed leakage [4]. Postoperative ileus was defined as an inability to tolerate food in the presence of abdominal distention, absent bowel sounds, and a need to delay enteral feeding [5]. Rhabdomyolysis was defined by serum CK levels >5000 IU/L [6]. ACS was defined as high pressure within a closed fascial space (muscle compartment) causing reduced capillary blood perfusion below the level necessary for tissue viability [7]. Rhabdomyolysis and ACS were diagnosed using the CTCAE grading system. Finally, operative mortality was compared based on a definition as any death that occurred within 30 days after the primary operation.
Statistical analysis
We used JMP version x software (SAS Institute Inc., Cary, N. C., USA) for the statistical analysis. Categorical variables were compared using chi-squared or Fisher’s exact tests, as appropriate. Continuous variables are presented as medians and were compared using the Mann–Whitney U test or analysis of variance. The Spearman’s rank correlation coefficient was used to evaluate correlations.