Robotic surgery is considered as one of the advanced treatment modality of minimally invasive surgery for rectal cancer. Robotic rectal surgery has been performed for three decades and its application is gradually expanding along with technology development. It has several technical advantages which include magnified three-dimensional vision, better ergonomics, multiple articulated robotic instruments, and the opportunity to perform remote surgery. The technical benefits of robotic system can help to manipulate more meticulously during technical challenging procedures including total mesorectal excision in narrow pelvis, lateral pelvic node dissection, and intersphincteric resection. It is also reported that robotic rectal surgery have been shown more favorable postoperative functional outcomes. Despite its technical benefits, a majority of studies have been reported that there is rarely clinical or oncologic superiority of robotic surgery for rectal cancer compared to conventional laparoscopic surgery. In addition, robotic rectal surgery showed significantly higher costs than the standard method. Hence, the cost-effectiveness of robotic rectal surgery is still questionable. In order for robotic rectal surgery to further develop in the field of minimally invasive surgery, there should be an obvious cost-effective advantages over laparoscopic surgery, and it is crucial that large-scale prospective randomized trials are required. Positive competition of industries in correlation with technological development may gradually reduce the price of the robotic system, and it will be helpful to increase the cost-effectiveness of robotic rectal surgery.
Minimally invasive surgery has remarkably developed during the past decades, but, it is still challenging and needs a lot of technical demands. In the early 1990s, laparoscopic surgery appeared and has grown rapidly, then has been established as a standard method of minimally invasive surgery.1 According to several randomized studies, comparing open surgery, laparoscopic surgery has clinical benefits including smaller incisions, shorter hospital stay, and better postoperative recovery with comparable oncologic outcomes.2–4 Meanwhile, the robotic system provides magnified three-dimensional vision, better ergonomics, multiple articulated robotic instruments, and an opportunity to perform remote surgery.5 In terms of the advantage to approach narrow pelvic cavity, robotic surgery has been used prominently in the urologic and gynecologic fields. In recent, robotic rectal surgery including a robot-assisted laparoscopic approach or totally robotic surgery is increasing and regarded as an effective and surgeon-convenient treatment option that is suggested to overcome the limitations of laparoscopic surgery.6 Even though robotic surgery has those technical advantages, the cost-effectiveness of robot-assisted rectal surgery is still debatable. We herein reviewed the overview of robotic rectal surgery, and discussed in terms of cost-effectiveness based on the literatures.
The surgical use of a robot in a machine has approximately 30 years of history.7 The first clinical use of a robot for surgery was the Automated Endoscopic System for Optimal Positioning (AESOP; Computer Motion Inc. Santa Barbara, CA), developed by Wang, in 1993. In the next year, AESOP was approved by the Food and Drug Administration (FDA) as an endoscopic camera manipulator. A few years later, the Zeus system (Computer Motion, Inc., Santa Barbara, CA) was invented with surgical arms and instruments, but it had a limited role as an assistant. After then, the da Vinci® system (Intuitive Surgical, Inc., Mountain View, CA) has been used in general surgery. Zeus system was decided to stop production in 2003, hence, the da Vinci® system is the only available surgical robot.8,9 Since Jacques Himpens and Gut Cardiere performed the first robot-assisted cholecystectomy in 1997, various general surgical procedures were performed with the da Vinci® system.7,10 In the early 2000s, Hashizume and Weber reported the first robotic colectomy for malignant and benign disease respectively.7,11,12 The first radical mesorectal excision of rectal cancer using the da Vinci® system was reported by Pigazzi et al.13 in 2006. Up to now, the da Vinci® system is developed Xi version with reduced docking time and improved image quality, and additionally, SP version for surgical access of narrow space.
Robotic rectal surgery has several benefits compared with conventional laparoscopic surgery. It offers magnified three-dimensional view, hand-tremor filtering, fine dexterity with wrist articulation, surgeon comfort in console, and, assistant-independent operation of working arms and camera.5,14,15 The high resolution of the robotic visual system is helpful to preserve the pelvic autonomic nerve.16 Furthermore, better ergonomics and surgeon comfort design including sitting available at a console during surgery, and meticulous EndowristTM (Intuitive Surgical, Sunnyvale, CA, USA) movement might reduce the fatigue of operator compared to conventional laparoscopic surgery.17 Especially, robotic total mesorectal excision (TME) has a potential benefit because of its technical difficulty to access the narrow pelvic cavity.13 Beak et al.16 reported that there was no significant difference among the easy, moderate, and difficult pelvic anatomy groups stratified by MRI-based pelvimetry, in terms of operation time and other perioperative outcomes for robotic TME. It implied that robotic approach can be comfortable to access narrow cavity, and it is more helpful to overcome difficulties regarding pelvic anatomy. In addition, several studies suggested that better recovery of urinary and sexual function in the robotic rectal surgery group comparing the laparoscopic rectal surgery group for the reason of more precise and meticulous dissection in robotic TME.18–20 For the same reason, robotic system is regarded as a useful option when technically demanding procedures are required such as intersphincteric resection, or lateral pelvic lymph nodes.21–23
On the other hand, there is controversy regarding high cost, patient repositioning difficulty, complete loss of tactile feedback, and prolonged operative time.1,15,24,25 The docking procedure of the robotic cart is required more time and additional efforts. Furthermore, it is difficult to remove the robotic cart promptly, when an emergent open conversion is necessary, such as uncontrolled bleeding. Tactile feedback is useful during surgery, which provides numerous sensations when surgeons manipulate surgical procedures such as traction, palpation, grasping, pulling, and push of the structure, moreover, notification of tissue damage. Although technical development may improve the haptic feedback of the robotic surgical system, it does not yet provide the fine haptic feedback to the surgeon as accurately as the human touch sensation.26,27 The high cost is the main drawback of robotic surgery. The cost analysis is described at the bottom of the body text.
Although laparoscopic rectal surgery has been an alternative treatment of open surgery, in terms of surgeon’s training, it requires a steeper learning curve than open surgery, because of its non-ergonomic surgical instruments and limited surgical view.28,29 The robotic surgical system provides better ergonomic tools, and high-resolution three-dimensional vision, therefore, it is expected that the learning curve is shorter than the laparoscopic procedure.
The learning curve of robotic rectal surgery was reported rage from 15 to 40 cases,30–35 whereas the value of laparoscopic rectal surgery was reported 30 to 70 cases.28,36,37 The learning curve of robotic surgery may be seen shorter than laparoscopic surgery, however, most studies have a single-arm design, and they have consisted of a small number of patients.
Park et al.38 analyzed a single junior surgeon’s learning curve of robotic TME for rectal cancer with 89 cases and compared them with the same size of conventional laparoscopic surgeries using the cumulative sum (CUSUM) method. In this study, the single surgeon started laparoscopic and robotic TME almost simultaneously. The learning curve of robotic surgery for rectal cancer was 44 procedures and laparoscopic surgery was 41 procedures. According to the study, the learning curves between the two methods showed similar results with comparable clinicopathologic outcomes.
However, a majority of published studies did not consider the surgeon’s prior experience of rectal surgery, which could affect the learning curve as a bias. Furthermore, the case complexity could be one of the influencing factors. Darcy et al. suggested that robotic rectal surgery may accelerate the learning curve when operating more complex cases compared with laparoscopic surgery because the perioperative outcomes were improved while case complexity increased.39 Therefore, the superiority of the learning curve between laparoscopy and robotic rectal surgery is controversial, and further studies should consider influencing factors that may cause bias.
It is established that robotic rectal surgery is safe and feasible compared to conventional minimally invasive surgery. Although the results in detail might vary depending on the studies, the recent comparative studies between laparoscopic and robotic TME for rectal cancer showed overall comparable clinical outcomes (Table 1).40–48 In 2008, Baik et al.40 reported a pilot randomized controlled study for comparing robotic and laparoscopic tumor-specific mesorectal excision (TSME) with a small population, the results showed that the mean operative time was not significantly different between the two groups (217.1±51.6 vs. 204.3±51.9,
In terms of estimated blood loss (EBL) during operation, most of the studies reported that there was no significant difference between robotic and laparoscopic rectal surgery. According to Kim et al.46, the median EBL was higher in the robotic surgery group than in the laparoscopic surgery group (100 mL vs 50 mL,
The length of hospital stay (LOS) of robotic TME is generally similar or slightly shorter than laparoscopic surgery.40–48 Baik et al.40 presented the mean LOS of robotic rectal surgery was shorter than the laparoscopic approach (6.9±1.3 days vs 8.7±1.3 days,
Regarding postoperative morbidity, robotic surgery has barely shown a significant difference compared to laparoscopic surgery. The complication rates of robotic TME were ranged from 14.3% to 47.6%, while those of laparoscopic TME were ranged from 5.5% to 49.4%.40–48 Meanwhile, according to Baik et al.49, overall postoperative complication rates of both groups had no statistical difference (10.7 vs 19.3,
The range of conversion rate of robotic rectal surgery has been reported 0 to 12%.40–48 It is shown that the conversion rate of robotic TME had no statistical difference compared with laparoscopic TME,40,43–46 whereas, several studies suggested that robotic TME had a lower conversion rate than that of laparoscopic TME.41,42,48 According to the ‘Robotic vs Laparoscopic Resection for Rectal Cancer (ROLARR)’ randomized controlled trial which published the primary results at JAMA in 2017, there was no significant difference in conversion rates between robotic TME and conventional laparoscopic TME (8.1% vs 12.2%,
One of the potential benefits of robotic rectal cancer surgery is that it can lead better perioperative functional outcomes regarding voiding and sexual aspects. Pelvic autonomic nerve injury during TME procedure is a crucial cause of voiding and sexual dysfunction. The International Prostate Symptom Score (IPSS) and the International Index of Erectile Function (IIEF) questionnaires are generally used to assess urogenital dysfunction. According to a systematic review and meta-analysis, in ten studies including 689 patients which were evaluated the functional outcomes by IPSS and IIEF, robotic rectal surgery showed early improved urogenital function compared to laparoscopic rectal surgery.51 In recent, Wang et al.52 also reported that robotic rectal surgery showed less incidence of male urinary and sexual dysfunction. The postoperative 12 months total IPSS scores were significantly lower in robotic group than laparoscopic group (6.79 vs 9.66,
The oncologic outcomes of robotic TME are generally comparable to those of laparoscopic TME. Table 2 shows the oncologic outcomes of robotic TME for rectal cancer compared with conventional surgery in recently published studies, and there are rarely statistical differences between robotic TME and laparoscopic TME.40–48
The completeness of oncologic resection was reflected by the pathologic outcomes of the specimen including the number of harvested lymph nodes (LN), circumferential resection margin (CRM), and distal resection margin (DRM). The harvested LN of both groups were mostly more than 12 in the majority of studies. According to Kim et al.46 and Asoglu et al.47, the number of harvested LN of the robotic group was statistically higher than that of the laparoscopic group (18 vs 15,
In short-term oncologic outcomes of robotic TME, the 3-year overall survival (OS), and 3-year disease-free survival (DFS) were ranged 90.1~97.0%, and 73.7~79.2%, respectively.49,53–58 Pai et al.54 reported that the local recurrence was 4% and the systemic recurrence was 17%. Another study by Baek et al.53 reported that the local recurrence was 3.1% with the mean time of 23 months, and the systemic recurrence was 6.3%. According to Feroci et al.59, comparing with laparoscopic TME, robotic TME did not show statistical difference regarding 3-year OS (robotic vs laparoscopic; 90.2% vs 90.0%,
Park et al.42 reported the first article to compare the long-term oncologic outcomes between robotic and laparoscopic rectal surgery during the mean follow-up of 54.4 months. The 5-year OS (robotic vs laparoscopic; 92.8% vs 93.5%,
Up to now, although expecting that robotic TME would improve the quality of the specimen through technically more meticulous manipulation than laparoscopic TME, previous results have not provided a clear advantage in pathologic, short-term and long-term oncologic outcomes. However, there have been no results of level I evidence, randomized controlled trial will be required. The long-term follow up results of the ROLARR trial which is the largest multicenter randomized study will be quite helpful to establish robotic rectal cancer surgery regarding oncologic surgery and selection of surgical approach.
In order to shift the paradigm of specific therapeutic modality in modern medicine, not only the clinical outcomes of the patients, but also the price competitiveness should be available. The main drawback of robotic surgery is relatively higher costs compared to laparoscopic surgery. In general, the overall total costs for one patient from hospital admission to discharge are consisted of operative costs (including the cost of the operation room in relation to the operative time, and laparoscopic or robotic devices, consumable instruments, etc.) and other hospitalization costs (including the cost associated with length of hospital stay; medication, nursing care, blood transfusion, radiologic exam, nutrition, fluid administration, other consumables, etc.). Table 3 demonstrates the recently published studies regarding cost analysis of robotic TME for rectal cancer comparing with the conventional approach. Almost all the studies suggested that robotic TME had definitely higher costs than laparoscopic surgery.42,44,45,60–64
In South Korea, Baek et al.60 reported that total hospital charges of robotic rectal surgery are larger than those of laparoscopic rectal surgery (14647 vs 9978, USD,
In Italy, Morelli et al.62 reported a single surgeon’s initial 50 robotic rectal resection experience focusing on cost analysis according to the learning curve using the CUSUM method comparing with laparoscopic TME. They divided the costs into two categories which are fixed costs (costs related to robotic equipment or laparoscopic device), and variable costs (costs related to disposable instruments, operating room personnel, and length of stay). Based on the CUSUM method, the robotic TME group was divided into three phases (Rob1: 1~19, Rob2: 20~40, Rob3: 41~50) and there was a statistical change in the operative time of each phase. Total costs were significantly higher in the robotic TME group (12283.5 vs 7619.8, EUR,
In Canada, Ramji et al.44 compared the clinical and economic outcomes among three approaches of rectal cancer surgery (open, laparoscopic, and robotic) in a publicly funded healthcare system. There was no statistical difference for total costs and operative costs between open and laparoscopic method, whereas, robotic surgery added approximately 6000 CAD to the median costs of each operation, increasing the average cost of stay for a patient by 1.5 times with similar clinical outcomes (Operative costs: open vs laparoscopic vs robotic, 4339.63 vs 5313.59 vs 11879.66, CAD,
In Spain, Ielpo et al.63 reported a comparative study of clinical outcomes and costs for robotic versus laparoscopic surgery for rectal cancer. The mean operative costs were significantly higher for the robotic group (4285.16 vs 3506.11, EUR,
There was a largely populated retrospective analysis using the Nationwide Inpatient Sample database in the United States.64 After propensity score matching, the study included 883 matched patients each in the open and laparoscopic group, and 551 matched patients each in the laparoscopic and robotic group. Although the p value was not demonstrated, the robotic group had a higher median total cost comparing with the laparoscopic group (20628 vs 17671, USD). For further analysis, using odd ratio, the robotic group had a significantly higher cost than laparoscopic group (odds ratio 1.42, 95% confidence index 1.13~1.79), but no benefit over laparoscopic surgery in terms of mortality and morbidity.
In summary, almost all studies suggested that robotic TME showed higher cost comparing with laparoscopic TME while the overall clinical outcomes were similar. After the learning curve for robotic TME, the operative costs could be reduced, but the total costs including fixed costs were still higher because of the expensive purchasing charge for the robotic system. Because of a majority of published studies regarding cost analysis for robotic TME is retrospective study, large populated prospective randomized studies on the cost-effectiveness of robotic surgery may be warranted.
Robotic surgery for rectal cancer is not only feasible and safe but also has various potential benefits especially surgeon-centered technical advantages compared to the conventional laparoscopic rectal surgery. Robotic system is considered as one of useful options when technical demanding procedures including TME in narrow pelvis, lateral pelvic nerve dissection, or intersphincteric resection are needed. However, robotic rectal surgery showed significant higher costs than laparoscopic surgery with similar overall clinical outcomes. The overall costs are higher in robotic surgery than the laparoscopic approach, especially it is account for manifestly expensive operative costs. Therefore, although robotic rectal surgery has several benefits, it is not enough to be a cost-effective approach in the field of minimally invasive surgery in the present time. Because of the price of robotic equipment is mainly high, it may lead to different results in the future. Positive competition of industries in correlation with technological development may gradually reduce the price of the robotic system, and it will be helpful to increase the cost-effectiveness of robotic rectal surgery with acceptable results of large populated prospective randomized studies.
Conceptualization: SHB. Formal analysis: YBJ. Methodology: EJP, YBJ. Writing-original draft: YBJ. Writing-review and editing: YBJ, EJP, SHB.
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2017R1A2B2011520).
The authors would like to thank Ms. MiSun Park for the English editing of this paper.