Laparoscopic and robotic lateral lymph node dissection for rectal cancer

Multiple recent studies have been published on the feasibility of laparoscopic LPLND, short-term outcomes of which have been reported, mainly from Asian countries, since 2011 (Table 1) [13, 22‐24]. Although these studies were retrospective case series, the short-term outcomes were reasonable, with median estimated blood [25] loss of 25–213 mL and rates of conversion of 0–17%. Yamaguchi et al. reported a multicenter case-matched study that compared laparoscopic and open LPLND for stage II or III low rectal cancer [26]. They found that the laparoscopic group had a longer operation time (474 min vs. 363 min), less blood loss (213 mL vs. 775 mL), less blood transfusion (6.8% vs. 22.2%), similar rates of grade III or IV complications (23.7% vs. 22.9%), and no mortality. Data on the long-term oncologic outcomes of this procedure are relatively limited. A case series of 107 patients who underwent laparoscopic LPLND after NACRT at a single cancer center in Japan reported 95.8% 3-year overall survival, 84.7% 3-year relapse-free survival, and a 3.2% 3-year local recurrence rate [27]. The patients in that series all had cT3/4 extraperitoneal low rectal cancer with clinically positive lateral nodes; therefore, these data support the oncologic rationale for performing this procedure. A retrospective multicenter case-matched study from Japan, comparing laparoscopic and open LPLND reported 93.9% 3-year overall survival, 93.9% 3-year local recurrence-free survival, and 80.3% 3-year relapse-free survival in the laparoscopic group. These values were all similar to or better than those for the open group [26]. Although prospective validation studies are warranted, these outcomes indicate the technical safety and feasibility of laparoscopic LPLND.

Robotic LPLND was first described by Park et al., who reported a series of eight patients [29], since when other authors have documented their results (Table 2) [30‐35]. Robotic surgery has the advantages of using multi-joint forceps with a motion scaling, high-quality three-dimensional camera and greatly improved ergonomics, which are all ideal for complex procedures such as LPLND. Yamaguchi et al. reported the short- and long-term oncological outcomes of robotic vs. open LPLND [32, 34]. Robotic LPLND was associated with less blood loss (25 mL vs. 637 mL, P < 0.001), less need for blood transfusion (0% vs. 10.2%, P = 0.003), longer operative time (455 min vs. 410 min, P = 0.007), and fewer postoperative complications (wound infection 0% vs. 8.0%, P = 0.014; small bowel obstruction 3.5% vs. 15.9%, P = 0.009; anastomotic leakage 0% vs. 9.1%, P = 0.007; urinary retention 18.8% vs. 36.4%, P = 0.011) than the open procedure. That study also reported similar 5-year overall survival rates (95.4% vs. 87.8%, respectively; P = 0.106) and 5-year relapse-free survival rates (79.1% vs. 69.9%, P = 0.157) for robotic LPLND and the open procedure, but noted that robotic LPLND had superior 5-year local relapse-free survival (98.6% vs. 90.9%, P = 0.029). Kim et al. compared the short-term outcomes of robotic vs. laparoscopic LPLND [35]. Whereas the operative time was similar in the two groups, the estimated blood loss and the incidence of Foley catheter reinsertion for urinary retention after surgery were lower in the robotic group. Overall and local recurrence rates did not differ between the groups. Although there is limited evidence directly comparing robotic and laparoscopic LPLND, a robotic approach is generally regarded as a reasonable alternative for this complicated procedure, particularly in Western countries where LPLND is not standard.

The technical procedures of laparoscopic LPLND are well established and have been standardized by multiple authors [13, 36]. The important advantage of laparoscopic LPLND is a better surgical view within the deep pelvis, which allows for identification of the pelvic vessels and autonomic nerves (Fig. 2a). Typically, LPLND should be performed after completion of TME and before anastomosis. No additional trocars are needed after TME. The obturator and internal iliac nodes are the most important to dissect because they cover most of the curable lateral node metastasis from rectal cancer. To dissect these two areas, three planes should be recognized: the lateral pelvic wall plane, which is composed of the psoas and internal obturator muscles; the medial plane, composed of the ureter and the pelvic plexus; and the dorsal plane, composed of the internal iliac vessels and the sciatic nerve (Fig. 2b). These three planes surround the area to be dissected. Another important plane divides the area into the obturator and internal iliac compartments: the vesicohypogastric fascia, composed of the bladder, internal iliac artery, and the urinary branches (the umbilical and superior vesical and inferior vesical arteries; Fig. 2c). Dissection along these planes minimizes bleeding and prevents incomplete dissection in LPLND.

The reported postoperative complication rates of laparoscopic and robotic LPLND range from 7 to 41% and 25 to 39%, respectively (Table 3) [13, 22‐29, 32, 33, 35]. These rates are equal to or lower than the complication rates after open procedures [3, 26, 32]. Ogura et al. reported that the incidence of major complications (grade ≥ 3) after laparoscopic LPLND was 9.3%, including anastomotic leakage, pelvic abscess, ileus and postoperative bleeding [27]. Bae et al. reported a postoperative complication rate of 28% after laparoscopic or robotic LPLND, including anastomotic leakage, ileus and chyle leakage [25]. Kim et al. compared the short-term outcomes of laparoscopic and robotic LPLND and found that the incidences of postoperative complications were similar (28% vs. 34%, respectively; P = 0.63) [35]. Yamaguchi et al. reported that the rates of wound infection, small-bowel obstruction, and anastomotic leakage after robotic LPLND were lower than those after open LPLND (P < 0.05 for all) [32].

Postoperative urinary and sexual dysfunction are major complications after rectal surgery and the addition of LPLND has been reported to result in more genitourinary dysfunction than TME alone [37‐42]. However, nerve-preserving techniques minimize this dysfunction after LPLND [43, 44]. A recent Japanese RCT reported similar rates of sexual and urinary dysfunction after TME alone vs. TME plus LPLND through an open approach (male sexual dysfunction, 68% vs. 79%, respectively; P = 0.37; subclinical urinary dysfunction with ≥ 50 mL residual urine, 59% vs. 58%, respectively) [5, 6]. The authors concluded that if autonomic nerve-preserving procedures are done, LPLND does not increase the risk of sexual or urinary dysfunction. A few studies have investigated genitourinary dysfunction after laparoscopic and robotic LPLND. Liu et al. reported adequate urinary function after laparoscopic LPLND [45]. At a high-volume center in Japan with experienced laparoscopic surgeons, the incidence of postoperative urinary dysfunction was minimal [13, 27]. Manabe et al. reported that combined resection of the bilateral inferior vesical arteries was a risk factor for postoperative urinary dysfunction after laparoscopic LPLND [46]. It should be noted that not only the autonomic nerves but also the inferior vesical arteries are closely associated with functional outcomes after LPLND. Although the data are limited, robotic LPLND may allow for better handling of these structures, resulting in a lower incidence of postoperative genitourinary dysfunction than after open or laparoscopic LPLND [32, 35]. The risk of postoperative complications after LPLND is influenced by multiple factors, including whether the procedure is prophylactic or definitive and unilateral or bilateral. Case-matched prospective validation studies are needed to investigate this further.