Two of the large rectal cancer trials (the MRC CLASICC trial and the COREAN trial) [3, 7] have reported long-term outcomes comparing laparoscopic to open surgery. The results are summarized in Table 10.2. No differences between laparoscopic and open surgery have yet been observed with respect to the risk of local recurrence, distant metastasis, or overall survival. However, both the COLOR II and ACOSOG Z6051 trials have yet to publish long-term outcomes at the time of preparation of this summary.

A Cochrane review of both colon and rectal cancer patients found no differences in 5-year overall survival (OR 1.15, 95% CI 0.87–1.52, P = 0.32), 5-year local recurrence (OR 0.94, 95% CI 0.49–1.81, P = 0.32), distant recurrence (OR 0.97, 95% CI 0.70–1.32, P = 0.80), or port site/wound recurrence (2.76, 95% CI 0.75–10.20, P = 0.13) [8] between open and laparoscopic surgery. Thus, the currently available data appear to support minimally invasive surgery for rectal cancer, reporting short-term benefits similar to those seen in colon cancer.

In light of the observed short-term benefits of minimally invasive surgery compared to open surgery—as well as increased technical expertise on the part of clinicians and improvement in technique and devices—the use of laparoscopic colon surgery has increased dramatically during the past two decades. Kang et al. compared the frequency of laparoscopic surgery from 2007 to 2009 using the National Inpatient Sample. They found that the proportion of patients undergoing a laparoscopic right colectomy increased from 13% in 2007 to 49% in 2009 [7]. A large increase was also seen in laparoscopic sigmoid resection (18% in 2007 to 55% in 2009). In addition, the rates of conversion in sigmoid resection dropped dramatically between 2007 and 2009, indicating significant advances along the surgical learning curve, as well as improved instrumentation. However, during this time there was very little increase in the use of laparoscopic surgery for low anterior resection of rectal cancer (12% in 2007 to 16% in 2009) [9] (Figs. 10.1 and 10.2).

The difficulty in adapting laparoscopic techniques to rectal cancer surgery stems from the anatomical restrictions imposed by the operative field and the technical demands of these procedures. The narrow, bony pelvis can inhibit proper visualization of anatomical landmarks and restrict surgical movement; furthermore, it is hardly an ideal space for the straight, rigid instruments used in traditional laparoscopy. The limitations inherent in maneuvering laparoscopic instruments and the difficulty in achieving proper retraction are a challenge. The proximity of other pelvic organs adds a layer of difficulty not encountered in segmental colon resection. In addition, there is the potential for collision of instruments within the small pelvic working space. In rectal cancer surgery, the need for complete and total mesorectal excision (TME) , entailing exact and sharp dissection of the mesorectal fascia, is paramount. Achieving nerve preservation in order to maintain the patient’s postoperative bladder and sexual function, whenever possible, is also an important goal.

Many of the limitations of laparoscopic pelvic dissection can be eliminated when using the robotic surgical platform. The robot’s articulating instruments facilitate dissection within the difficult confines of the pelvis. A stable camera platform, and the ability of the surgeon to control camera location, provides greatly enhanced 3-D visualization of the operative field—far superior to the two-dimensional visuals provided by the laparoscope. Retraction with the third robotic arm—so difficult to achieve with traditional laparoscopic instruments—can be controlled directly by the operating surgeon without impingement on the working space. In addition, the articulating instruments decrease the risk of collision.

The safety and efficacy of robotic rectal surgery has been assessed in a number of observational studies as well as in several small randomized, controlled trials. The largest trial, robotic vs. laparoscopic resection for rectal cancer (ROLARR trial) , is currently open to accrual and anticipates enrolling 400 rectal cancer patients. The primary outcome will be conversion to open surgery. Secondary outcomes include circumferential radial margin and other margin positivity. The investigators will also examine morbidity and mortality, 3-year disease-free survival, and postoperative sexual function [10].

Currently, several meta-analyses have been completed [11–13]. The findings are summarized in Table 10.3. These studies consistently reported a lower risk of conversion to open surgery in the robotic group (OR 0.26, 95%CI 0.12–0.57) (Fig. 10.3). A meta-analysis of randomized, controlled trials [14] focused on four studies comparing robotic to laparoscopic surgery in colorectal cancer. The conversion rate was found to be lower in the robotic group (OR 0.26, 95% CI 0.12–0.57) (Fig. 10.4). There was no difference in length of stay, rate of complications, or number of harvested lymph nodes. A large population-based study [9] also compared rates of conversion between laparoscopic and robotic surgery, with similar findings (Fig. 10.5). Unlike laparoscopic rectal resection, patient obesity and low-lying tumors are not strongly associated with conversion in robotic surgery [15, 16].