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Page 8 of 12 Chen et al. Mini-invasive Surg 2018;2:43 I http://dx.doi.org/10.20517/2574-1225.2018.42

R0 resection 57
Locoregional recurrence 2 (3.5%)
Distant metastasis 5 (8.8%)
Lung 1 (1.75%)
Liver 2 (3.5%)
Liver + Lung 1 (1.75%)
Peritoneal carcinomatosis 1 (1.75%)
R1 resection 3
Local recurrence 1 (33.3%)
Lung 1 (33.3%)
Peritoneum 1 (33.3%)

AJCC: American Joint Commission on Cancer; CCRT: concurrent chemoradiotherapy

[16]
shown that the robotic approach to colorectal surgery is safe and feasible . Most crucially, favorable short-
term clinical and oncological outcomes can be achieved by combining complete robotic-assisted TME with
appropriate preoperative CCRT. At least 12 lymph nodes should be examined for each surgical specimen of
colorectal cancer, as recommended in the American Joint Commission on Cancer/Union for International
Cancer Control guidelines. However, this recommendation was mainly based on studies of colon cancers.
[17]
Chou et al. reported that patients with rectal cancers and older patients who had distally located, early
[18]
colon cancer were less likely to meet the recommended lymph node yield of 12. Besides, Persiani et al.
showed that a low lymph node count after neoadjuvant chemoradiotherapy for rectal cancer does not signi-
fy inadequate resection or understaging but represents increased sensitivity to the treatment. Additionally,
preoperative chemotherapy significantly reduces the number of lymph nodes that can be harvested, with
the mean number of detected nodes ranging between 4 and 14 per specimen. In this study, the median
[18]
number of harvested lymph nodes was 8 (range, 0-36), which is consistent with the literature .
[19]
The results of this study were consistent with those of a meta-analysis conducted by Scarpinata and Aly .
The selection criteria for robotic surgery in this meta-analysis were obesity, male sex, preoperative radio-
therapy, and tumors in the lower two-thirds of the rectum. The pCR rate after CCRT observed in our study
was 36.7%, which is slightly higher than in previous studies [20,21] . The introduction of oxaliplatin-based
chemotherapy and a longer interval may be the major reasons for the higher pCR rate as in our previous
[22]
study . The sphincter preservation rate achieved in our study was 93.3% (56/60), which is comparable with
[24]
[23]
that reported by Kim et al. and Saklani et al. .
Two pathological assessments appear to be crucial in judging the standard of surgery: CRM involve-
ment and the gross appearance of the surgically resected specimen. Moreover, CRM involvement has
been reported as a prognostic factor for local recurrence and survival [25-28] . In this study, the rate of CRM
involvement was 5%, with a median distance of 1.1 cm, which is comparable with that reported in other
studies (0%-16.1%) [Table 4]. Moreover, the rate of DRM involvement was 1.7%, with a median distance of
1.9 cm, which is also comparable with that reported in previous studies [Table 4]. R0 resection for primary
rectal cancer was performed in 57 (95%) patients, 2 of whom developed local recurrence and 5 of whom
developed distant metastasis. We attempted to perform R0 resection in all patients, but R1 resection was
performed in three patients. One such patient was a 59-year-old woman at clinical stage cT4bN2bM0 with
uterus invasion. Neoadjuvant chemotherapy was performed first, followed by robotic ISR 55 days later.
The pathology report showed positive CRM, but the DRM was free. During follow up period, she died of
intraabdominal infection 2 years and 10 months after operation. The second patient was a 61-year-old man
at clinical stage cT4aN2bM0 with visceral peritoneum invasion. Neoadjuvant chemotherapy was performed
first, followed by robotic ISR 85 days later. The pathology report showed positive CRM, but DRM was free.
During follow up period, he died of pneumonia 9 months after operation. The third patient was a 53-year-
old woman at clinical stage cT4bN2bM0 with posterior vaginal wall invasion. Neoadjuvant chemotherapy