Different treatment strategies have evolved in Eastern and Western countries to reduce the local recurrence rates of rectal cancer. In most Western institutions, neoadjuvant therapy, especially preoperative radiation therapy, is most commonly employed in conjunction with TME. Many surgeons in Western countries are still skeptical about the value of LPLD for the treatment of advanced low rectal cancers because en bloc
lymph node dissection with pelvic autonomic nerve preservation is technically challenging. In the East, LP nodal involvement has been regarded as a factor associated with a poor prognosis, increased incidence of local recurrence, and reduced survival [2
]. Subsequently, a growing body of literature, mostly from Japanese institutions, supported the use of an extended pelvic lymphadenectomy for cases of advanced low rectal tumors. The incidence of local recurrence in patients with rectal cancer who undergo TME without LPLD in Western countries is reported to be less than 10% [11
]. Although this incidence is similar to that for patients undergoing TME with LPLD, a direct comparison is difficult because of differences in clinical backgrounds.
Only a few studies have reported the technical feasibility of laparoscopic LPLD with TME for rectal cancer [6
]. We previously reported 16 cases of laparoscopic LPLD for low rectal cancer after concurrent chemoradiation [8
]. All procedures were successfully performed without conversion to open surgery, and the mean blood loss and operative time were 190 mL and 310 minutes, respectively. Importantly, no severe urinary or sexual morbidity was observed in any of these patients. Although we have conducted laparoscopic LPLD in the past, it is difficult to be certain whether the robotic approach has provided clinical benefits over LPLD performed using conventional laparoscopy. We report only on the safety and the feasibility of robotic LPLD in this study because a comparative analysis would be flawed because of unmatched variables and a limited number of cases. Nevertheless, we have observed that lymph node dissection around the dedicated internal iliac vessel was easier when using a robotic interface.
Compared with conventional laparoscopy, one potential advantage of robotic LPLD may be the improved surgical view owing to 3-dimensional imaging and a surgeon-controlled camera platform. In addition, the surgeon can operate with two hands, using one, the assistant, to provide adequate exposure, compared to having just one hand for dissection, and the other for exposure, as is the case for conventional laparoscopy. The main vessel and its tributaries caused little difficulty during the dissection.
With the exception of surgeons in Japan, most surgeons do not use this procedure. Problems associated with LPLD, compared to typical conventional surgery, include urinary and sexual dysfunction and a longer operating time with greater blood loss. Recently, Georgiou et al. [15
] used a meta-analysis to evaluate the impact of an extended lymphadenectomy in treating rectal cancer and found that the extended lymphadenectomy did not confer a cancer-specific survival advantage and was associated with an increased incidence of complications (urinary and/or sexual dysfunction). Moriya et al. [16
] reported a mean operating time and blood loss of 393 minutes and 2,128 mL, respectively, for 53 patients undergoing LPLD with internal iliac vessel excision. Even center-of-excellence data on performing a LP lymphadenectomy showed a discouraging 5-year survival rate of 42% in patients with a positive lymph node and complete genitourinary functional loss in 33% of patients 2 years after LP node dissection [4
]. In our series, the median blood loss was 48 mL, and the median operation time was 273 minutes, calculated separately from the standardized TME procedure. Remarkably, none of the patients had accidental massive blood loss or conversion to open surgery. The postoperative mortality and morbidity rates were 0% and 25%, respectively, and no LPLD-related morbidity, such as lymphoceles and urinary dysfunction, were noted. The present study also showed rapid postoperative recovery, with a median hospital stay of 7.5 days, similar to that reported for most case series of laparoscopic colorectal surgery [6
]. We believe that the increased maneuverability of the instruments with a robotic system is the most likely reason for the short operation time and the reduced morbidity. In our center, robotic surgery is currently becoming central to the treatment strategy for patients with pelvic lymph metastasis.
As mentioned above, routine adoption of LPLD for patients with advanced rectal cancer is controversial because less than 15% of patients with locally advanced rectal cancer have lateral lymph node metastasis. Therefore, we adopt a more discerning policy in the selection of patients for LPLD, excluding patients with extraperitoneal rectal cancer when no radiologically-suspicious lymph nodes are identified. When radiologically-lateral lymph node metastasis is suspected and the patient's tumor is located in an extraperitoneal region, usually preoperative chemoradiation is performed first. TME is provided if lateral lymph node metastasis is not found after chemoradiation or if the tumor appears to be clinically benign. Conversely, even after preoperative chemoradiation, LPLD is performed when lateral node metastasis is suspected on MRI or positron emission tomography/CT. Under such selective conditions, the positive rate of lateral lymph node metastasis was 38%, 1.5 times higher than that previously reported in Japan. We expect the frequency of unnecessary LPLDs to be reduced if more sensitive radiologic criteria are established.
The current study has inherent limitations. It is retrospective in nature and has a small sample size. Functional and oncological outcomes are not sufficient, and the follow-up period is limited. Despite these limitations, this is the first report on a series of patients treated with robot-assisted LPLD following TME that documents the feasibility of this procedure. Robotic LPLD seems to have excellent short-term surgical and pathological outcomes and satisfactory functional results. Large-scale studies are needed to evaluate potential differences in the outcomes between conventional open, laparoscopy, and robot-assisted LPLD.