Currently, robotic platforms are used in numerous surgical departments, including general surgery, urology, gynecology, and cardiac and thoracic surgery. In the sphere of colorectal surgery, remarkable development has been achieved in minimally invasive surgery (MIS) and many favorable results have been recorded. MIS for colorectal cancer is associated with more favorable perioperative, oncologic, and functional outcomes (including satisfactory cosmesis) compared to conventional open laparotomy. However, laparoscopic surgery has several drawbacks. Laparoscopic surgery is conducted with limited range of movement and two-dimensional vision; it is associated with a high incidence of headache, visual deterioration, muscle pain and fatigue.¹ Additionally, surgeons need highly trained assistants, especially scopist, and a long learning period to obtain better operative results.² In particular, pelvic dissection is technically challenging due to limited visual exposure and paucity of space.³

Physicians expected the robotic platform to overcome the limitations of laparoscopic surgery. The robotic platform, i.e., the da Vinci system (Intuitive Surgical, Sunnyvale, CA, USA), affords surgeon-controlled, high-definition, three-dimensional (3D) vision and a sophisticated, angulated EndoWrist (Intuitive Surgical) with outstanding ergonomics and a great degree of range. It enables the detection of intravascular signals in real time after injection of Indocyanine green (Akorn, Lake Forest, IL, USA), via its intraoperative near infrared fluorescence imaging system (Firefly™; Intuitive Surgical).^4,5 It also filters the surgeons’ tremors.

Nevertheless, robotic surgery has been praised and criticized simultaneously because clear superiority over laparoscopic surgery in terms of outcomes has not been shown. Therefore, this review aimed to evaluate the benefits and drawbacks of robotic surgery for colorectal cancer through recent studies.

As aforementioned, robotic-assisted procedures have several benefits over laparoscopic procedures, as they allow a 3D view that enhances depth perception, including articulating wrists, filtering the surgeon’s tremor, and performing more sophisticated, ergonomic, and simultaneous movements. Further, robotic surgeries improve techniques and complicated procedures, facilitate access to confined spaces including the deep pelvis, and decrease the learning period.⁶ The robotic platform is particularly suitable for pelvic surgeries because its high quality camera, 3D vision, and the ergonomic, articulated EndoWrist facilitate the determination and manipulation of pelvic nerves and vessels and adjacent urologic and reproductive organs.⁶ Additionally, fogging decreases and clarity improves due to the heat generated at the tip of the dual lens system. Surgeons can control the camera like an operating arm; hence, there is less dependence on skilled laparoscopic assistants. Another important advantage of robotic surgery is the improved ergonomics of operating surgeons. Moreover, surgeons perform robotic surgery in a sitting position, which reduces the fatigue associated with complicated cases. In addition, with the production of da Vinci^® XI, incorporated slimmer arms do not require redocking or repositioning in multiple abdominal quadrants.^6,7

Robotic surgery can be performed feasibly by surgeons with little exprerience.⁶ The system improves surgical skills using the simulator mode and elicits scored verification of surgical skill and competence.⁸

Despite outstanding robotic technology and numerous studies on robotic surgery, considerable criticism and disadvantages of the technique remain. One of the limitations of robotic surgery is the absence of haptic and tactile feedback. Surgeons have no choice but to check the tension of the tissue using visual hints, including twisting, shearing, and blanching. Therefore, inexperienced surgeons are likely to injure tissues through excessive tension caused by an inappropriate grip.

Robotic surgery is associated with a longer operative time than laparoscopic surgery.^9–11 In robotic surgery, considerable time is spent during docking.

Another limitation is cost. A Korean study reported total charges of $14,647 for robotic low anterior resection (LAR) versus $9,978 for laparoscopic LAR (P < 0.001).¹² Another Korean study reported a total charge of $15,965 for robotic LAR versus $11,933 for laparoscopic LAR (P < 0.001).¹³

Total mesorectal excision

Total mesorectal excision (TME) is technically difficult, regardless of whether open or minimally invasive methods are used. TME involves the identification and separation of the rectum in the embryologic interface between the visceral and parietal fasciae along the holy plane, as described by Heald.¹⁴ It is also a representative surgical field in which the advantages of the robotic platform are greatly felt.¹⁵

Ohtani et al¹⁶ investigated 23 studies (n = 4,348) and revealed that preoperative chemoradiation was more frequent (P < 0.001) in the robotic group and that primary tumors were closer to the anal verge (P = 0.006) in the robotic group compared to the laparoscopic group. Despite this, the robotic group was associated with lower conversion rates than the laparoscopic group (P < 0.001). Cui et al¹⁰ investigated nine studies (n = 949) on rectal cancer and revealed that the robotic group showed lower conversion rates (P = 0.02), lower estimated blood loss, shorter hospital length of stay, and lower rates of postoperative complications compared to the laparoscopic group. Prete et al¹¹ examined five randomized controlled trials regarding rectal cancer on MIS and revealed that conversion to open surgery was less frequent (P = 0.04) and operating time was longer (P < 0.001) in the robotic group compared to the laparoscopic group. The ROLARR trial randomized 471 patients from 29 centers in 10 countries regarding rectal cancer surgery and reported no significant difference in the conversion rate between the robotic and laparoscopic groups. With subgroup analysis alone, the rate of conversion to open surgery was lower in the robotic group (especially among men) than in the laparoscopic group (P = 0.04).⁹ Most studies showed no significant differences in oncological outcomes between the robotic and laparoscopic groups.

Intersphincteric resection

Intersphincteric resection (ISR) involves dissection of the anal sphincter using an anus-preserving technique for low rectal cancer. In ISR, the space between the internal and external anal sphincters is separated; it is considered a safe alternative to abdominoperineal resection from an oncological perspective. This technique allows patients with low rectal cancers to get acceptable oncologic outcomes, avoids permanent stoma placement, and improves quality of life.¹⁷ ISR is very challenging to perform and technically demanding.

Piozzi and Kim¹⁸ examined three cohort studies and two comparative studies on ISR and reported that robotic ISR allowed adequate surgical resection margins and oncological outcomes and acceptable postoperative morbidities. Kim et al¹⁹ reported that the rate of circumferential margin positivity was ≤ 2% and that the local recurrence rate was 2.5% in the robotic ISR group. Moreover, protracted fecal incontinence resolved at 12–24 months after robotic ISR. According to several studies, robotic ISR may be technically efficient, allowing satisfactory anorectal function and favorable oncologic outcomes.

Transanal total mesorectal excision

In complicated circumstances including narrow pelvis, obese individuals, or patients with huge tumors, TME is more challenging (with high morbidity and lower negative surgical margin rates) regardless of the platform used.^20,21 Eventually, the idea of an alternative approach, a “bottom-up” technique from the distal plane to the proximal mesorectal plane, was suggested in place of the conventional ‘top-down” approach. This technique could result in a more accurate distal dissection according to the first clinical case report of transanal total mesorectal excision (TaTME) in humans published by Patricia Sylla and Antonio Lacy in 2010.²² Vignali et al²¹ evaluated several studies regarding TaTME and reported that TaTME showed morbidity and readmission rates similar to those of TME. The first case of robotic-assisted TaTME in humans was reported in 2013.²³ Hu et al²⁴ evaluated 20 patients who underwent robotic TaTME with the laparoscopic transabdominal approach. They reported that the primary anastomosis rate was 80% and that the involvement rate of circumferential margins was 15%.

As aforementioned, the introduction of the da Vinci^® SP could allow a more precise and stable transanal approach, including TaTME and transanal minimally invasive surgery (TAMIS), with single-port access; however, multi-port robot-assisted platforms including the da Vinci^® S, SI, and XI require sufficient space. Several cadaveric preclinical studies have been reported.²⁵ Marks et al²⁶ performed a prospective study on two patients with rectal cancers who underwent single-port TaTME. Their study showed perfect TME with negative margins and no long-term morbidity or mortality. Only preclinical cases and early experiences have been reported, so further research should be conducted to accurately assess the efficacy of robotic TaTME.²⁷

Transanal minimally invasive surgery

TAMIS is defined as transanal surgery for the excision of rectal lesions through a transanal single port using a minimally invasive system. Albert et al²⁸ described 50 patients who underwent TAMIS using standard laparoscopic equipment. However, TAMIS has not secured a stable surgical platform neither has it proven effectiveness in suturing the rectal wall due to ergonomic challenges.²⁹ However, robotic TAMIS has shown excellent suturing skill. Marks et al^30,31 reported two patients who underwent single-port TAMIS with negative margin involvement and no delayed morbidity or mortality.

The introduction of the da Vinci^® SP can bring natural orifice transluminal endoscopic surgery closer to use in colorectal cancer.

Lateral pelvic lymph node dissection

Routine lateral pelvic lymph node dissection (LPND) is controversial in the treatment of rectal cancer. LPND was performed to reduce local recurrence at the lateral sidewall of the pelvic cavity in rectal cancer patients. In Western countries and in Korea (unlike in Japan), to prevent morbidity (including urinary and sexual dysfunction), TME following neoadjuvant chemoradiotherapy without LPND is a standard treatment for locally advanced rectal cancer. However, the incidence of lateral pelvic lymph node metastasis is 18% in locally advanced low rectal cancer, and the lateral pelvic lymph node is one of the most common sites of recurrence.^32,33 Therefore, there is no doubt that LPND is a very crucial technique in colorectal cancer. LPND is a technically demanding procedure, especially when using the laparoscopic approach, with limitations of range and lack of articulation. The robotic approach may be advantageous because of the flexibility of the instrument, the 3D stereoscopic visuals, and articulation in a confined lateral pelvic space.

Kim et al³⁴ published a comparative study between laparoscopic (n = 35) and robotic (n = 50) LPND. In their study, the robotic group showed significantly lower estimated blood loss (P = 0.002) and urinary dysfunction rates (P = 0.029) than the laparoscopic group, whereas the overall recurrence rate was not different between the groups. Song et al³⁵ revealed that robotic TME with LPND was associated with low urinary retention (P = 0.043) and favorable 5-year survival (P = 0.017) rates. Hence, robotic LPND is recommended as a standardized and convenient procedure.

Colectomy

Minimally invasive colectomy shows clinical benefits including cosmesis and equivalent oncological outcomes compared to open surgery.^36,37 Additionally, 1.5 to 2.5 times more lymph nodes are retrieved in minimally invasive colectomies compared to open surgery.³⁸ However, the penetration rate of minimally invasive colectomies still remains approximately 40% to 50%.³⁹ Possible reasons for the limited clinical application of laparoscopic colectomy may include the challenges faced during extracorporeal anastomosis and complete mesocolic excision. Although difficult laparoscopic suturing is one of the reasons why intracorporeal anastomosis is not widely conducted during laparoscopic colectomy, however, robotic technique facilitated intracorporeal anastomosis. One of the advantages of intracorporeal anastomosis is the small extraction site, and the preferred low transverse incision site may result in better cosmetic outcomes and lower incisional hernia rates than the off midline transverse extraction sites. Above all, the overwhelming suturing ability of the robotic platform is undeniable. Robotic colectomy and intracorporeal anastomosis are beneficial, except with regard to cost.^40,41 Bianchi et al⁴² evaluated 161 robotic intracorporeal anastomoses for right colon cancers and revealed a conversion rate of 3.7%, anastomotic leakage rate of 0.6%, and 30-day readmission rate of 0.6%.

The da Vinci^® SP surgical system

Recently introduced, the da Vinci^® SP (Intuitive Surgical) can realize multiple complex procedures using one camera and three flexible arms. This system requires just one 2.5-cm incision for a single port. Since the advent of natural orifice transluminal endoscopic surgery, great expectations have been placed on the da Vinci^® SP regarding the transanal approach. Its use has rapidly expanded worldwide with the approval of the Food and Drug Administration.

Older patients

Several studies have reported that robotic surgery is feasible in geriatric patients. Cuellar-Gomez et al⁴³ reported that major complications were seen in 2.1% of patients and that the 30-day mortality rate was 0% in 76 consecutive patients (women, 52.6%) older than 75 years of age. Therefore, old age is not a contraindication for robotic colorectal surgery.

Patients with abdominal adhesions

A retrospective study by Park et al⁴⁴ reported that previous abdominal surgery did not worsen the perioperative outcomes of either laparoscopic or robotic colorectal surgery. Milone et al⁴⁵ examined 70 studies that performed 14,329 minimally invasive procedures (6,472 robotic and 7,857 laparoscopic) in patients with adhesions and reported that the robotic approach was associated with a significantly lower risk of conversion (P = 0.007). In addition, the conversion rate was low in patients who underwent colorectal cancer surgery in the robotic group (P = 0.02). The robotic approach might be a reasonable option for patients with abdominal adhesions. Therefore, previous abdominal surgery and adhesions should not be considered absolute contraindications for robotic colorectal surgery.

Obese patients

Harr et al⁴⁶ reported that after propensity score matching, obese patients who underwent robotic-assisted surgery had reduced odds of developing prolonged ileus (P = 0.03). Ahmed et al⁴⁷ examined rectal cancer patients with body mass indices ≥ 30 kg/m² and reported that there were significantly higher sphincter preserving rates (P = 0.045), shorter operating times (P = 0.013) and hospital stay (P = 0.001), lesser estimated blood loss (P < 0.001), and lower rates of conversion to open surgery (P = 0.043) in the robotic group compared to the laparoscopic group. Robotic surgery in obese patients may enable better functional and short-term outcomes.

Even though the learning curve of robotic surgery is steeper than that of laparoscopic surgery, robotic surgery is still technically demanding. Therefore, surgeons should have sufficient experience in performing robotic colorectal surgery. Since there is no tactile sense, inexperienced surgeons should familiarize themselves with visual hints of tissue tension.

Dry animals (including porcine) or cadaveric laboratories substantially improve the surgeons’ knowledge of tissue and suture tensile strength. Fortunately, the da Vinci^® system is equipped with a dual console system that enables inexperience surgeons to improve their surgical technique with graded responsibility during the operation.

Recently, Cambridge Medical Robotics introduced the Versius system with 5-mm arms instruments, no energy device or stapling instruments, and adequate cost-effectiveness. The 5-mm instruments are considered to be substantially advantageous in terms of cosmesis and pain. Medtronic presented its robotic system, but it is yet to be released. Johnson & Johnson recently announced that its robotic system projects are also in the advanced development phase and that they will be released soon. Several studies have reported that the new Senhance^® robotic platform is safe and feasible for colorectal cancer surgery.^48–50

In this review, we evaluated the recent advancements and limitations of robotic surgery. Although there have been a few studies on the favorable outcomes of robotic colorectal surgery, several studies have failed to reveal the supremacy of robotic surgery over laparoscopic surgery regarding oncological and postoperative outcomes; however, there might be lower rates of conversion to open surgery in robotic resections than in laparoscopic resections.⁵¹ Despite various criticisms regarding the high cost and long operative time associated with robotic surgeries, their use in colorectal cancers has continued to increase. Robotic colorectal surgery might have an advantage that has yet to be revealed. Thus, the difference between the two techniques should be determined in further studies.

In this review, we evaluated the recent advancements and limitations of robotic surgery. Despite the numerous advantages of robotic surgery, several studies have failed to reveal its supremacy over laparoscopic surgery regarding oncological and postoperative outcomes. Nevertheless, many surgeons have performed various robotic surgeries. Thus, further studies may provide clues for understanding the relevance of robotic colorectal surgery.

In this review, we evaluated the recent advancements and limitations of robotic surgery. Despite the numerous advantages of robotic surgery, several studies have yet to reveal its supremacy over laparoscopic surgery regarding oncological and postoperative outcomes. Nevertheless, many surgeons have performed various robotic surgeries. Thus, further studies may provide clues for understanding the relevance of robotic colorectal surgery.

None.

No potential conflict of interest relevant to this article was reported.