Laparoscopically assisted colectomy is as safe and effective as open colectomy in patients with colorectal cancer [16]. However, it has been reported that the long-term outcomes of laparoscopically assisted colectomy were unfavorable, and it was proposed that this was due to varying levels of proficiency among institutions [17]. Only a few studies have assessed the long-term outcomes of laparoscopic MVR of advanced colorectal cancers. Nishikawa et al reported that a laparoscopic approach was non-inferior to an open approach in terms of RFS (P = 0.578) [12]. In another study, Takahashi et al and Miyo et al reported that OS and RFS were comparable between the laparoscopic and open surgery groups [18, 19]. Mukai et al also reported that the short-term and long-term outcomes of laparoscopic surgery were equivalent to those of open surgery [20]. Our study presented detailed oncologic outcomes with a relatively long median follow-up period of 38.0 months. The 5-year OS and RFS rates for the laparoscopic and open surgery groups did not differ significantly in our study, similar to what was reported in previous studies.
The rates of pT4b were reported to be 28.2%-70.0% among patients undergoing MVR for colorectal cancer [6, 12]. Previous studies found that laparoscopic surgery was associated with a lower pT4b rate than open surgery [6, 12, 18]. They suggested that the lower pT4b rate in the laparoscopic surgery group meant that more advanced cases were included in the open surgery group. However, our pT4b rates were similar, with 44.0% in the laparoscopic surgery group and 42.1% in the open surgery group. The fact that pT4b rates were comparable in our study might be the result of more aggressive laparoscopy procedures being used for advanced cancers.
R0 resection is the most important factor in curing colorectal cancer with MVR [21]. Previous studies on MVR reported R0 resection rates of 68.4%-100% with laparoscopic surgery and 68.8%-98.5% with open surgery. Thus, our R0 resection rates were within the published range, with 92.0% in the laparoscopic surgery group and 94.8% in the open surgery group. Kim et al reported that the local recurrence rates after MVR in the laparoscopic and open surgery groups were 7.7% and 27.3%, respectively [22]. In our study, local recurrences occurred in two patients in the laparoscopic surgery group (8.0%) and in four patients in the open surgery group (10.5%), which suggested that our oncological clearance rate was acceptable. Our data support the notion that our laparoscopic surgery approach provided long-term outcomes similar to those provided with the open surgery approach, but with less invasiveness.
To prevent injury to vital organs, an early decision should be made about open conversion. Yang et al. described the optimal timing for open surgery conversion [23]. Though previous studies showed open conversion rates of 5.6%-23.0% with laparoscopic MVR, our open conversion rate, 13.8%, was within the range [24, 25]. For bulky locally advanced colorectal cancer, a preoperative detailed assessment of the anatomy around the tumor and an intraoperative well-timed decision about open conversion will avoid a high risk of severe complications. To secure a circumferential resection margin, obtain a better surgical view, or suppress micrometastasis, neoadjuvant chemotherapy may also be considered.
Our study has several limitations. First, it was retrospective, so some bias was present. Second, the determination of the operation type, open or laparoscopic surgery, was inconsistent, because it was determined by the attending physician and team at each institution considering the tumor size and the number of invaded structures or organs. Third, although the clinical and pathological tumor stages were comparable between the laparoscopic surgery and the open surgery groups, patients in the open surgery group tended to have more aggressive tumors, as indicated by the fact that the open surgery group tended to have larger tumor sizes and a higher rate of removal of two or more structures than the laparoscopic surgery group. Fourth, laparoscopic MVR for advanced colorectal cancers has increased in popularity over the years, as over half of the MVRs have been performed laparoscopically in recent years. Therefore, the first half of this study period includes mainly patients who underwent open surgery. Additional evidence is necessary to confirm the utility of laparoscopic surgery in this subset of patients with colorectal cancer who require MVR.
In conclusion, for patients with locally advanced colorectal cancer, the short and long-term outcomes of laparoscopic and open MVR were equivalent. However, performing laparoscopic MVR should be considered only by a specialized team.