Minimally invasive distal pancreatectomy (MIDP) has become increasingly popular over the last decade cause of its many advantages over the open approach such as the shorter hospital stay, reduced analgesic requirement, and reduced postoperative morbidity.1-3 Laparoscopic surgery confers many benefits such as smaller surgical scars, reduced blood loss, and faster recovery times.4-6 Nonetheless, its widespread adoption remains restricted due to the technically demanding nature of the MIDP especially with the straight rigid instruments used in conventional laparoscopy.

Presently, with the introduction of the da Vinci Robotic Surgical System (Intuitive Surgical, Inc., Sunnyvale, CA), surgeons can potentially overcome the limitations of traditional laparoscopy due to better dexterity from the patented endo-wrist, three-dimensional (3D) visualization, and better ergonomics.7-12 Some studies have shown that robotic surgery is a safe and feasible approach to DP but requires a longer operative time.1,5 However, presently there is no consensus on which approach (robotic or laparoscopic) is better as both techniques appear equivalent.10-15 This study summarizes our experience with robotic (RDP) and laparoscopic distal pancreatectomies (LDP), comparing between the clinical outcomes of RDP versus LDP.

During the study period, 102 patients underwent MIDP at our institution. 27 (26.5%) patients underwent RDP and 75 (73.5%) patients underwent LDP. Twenty-three (22.5%) patients underwent splenic preservation and the median difficulty score was 3. A total of 12 patients (11.8%) required an open conversion to complete the procedure. There were 22 successful SS-DP of which 4 were performed via the Warshaw technique and 18 via the Kimura technique. The median operating time was 280 minutes. Thirty-four (33.3%) patients experienced a postoperative morbidity. Of these, 16 (15.7%) patients had major morbidity, and 20 (19.6%) patients had a clinically significant pancreatic fistula. There was no 30-day mortality and 2 (2.0%) 90-day mortalities both in the LDP group. The median postoperative stay was 6 days.

There were 2 90-day reoperations. One was in a patient who underwent RDP and developed an incarcerated port-site hernia during the first week requiring repeat laparoscopic treatment and the other was in a patient who developed a large symptomatic pseudocyst after LDP requiring a cyst-gastrostomy. Details of the 2 90-day mortalities were as follows: The first patient was a 69-year old male with a history of previous kidney transplant on immunosuppression who underwent synchronous laparoscopic gastric resection for gastrointestinal stromal tumor, extended right hemicolectomy for colorectal cancer and distal pancreatosplenectomy for intraductal papillary mucinous neoplasm. He had a grade B pancreatic fistula which was well-controlled by the surgically placed drain. Unfortunately, he developed uncontrolled sepsis from nosocomial pneumonia and eventually demised on postoperative day 73. The second patient was a 70-year old male who suffered from an acute myocardial infarction 3 months before surgery. He underwent distal pancreatosplenectomy for pancreatic adenocarcinoma. During the second week of the postoperative recovery period, he suffered from spontaneous intracranial hemorrhage followed by an acute myocardial infarction, he subsequently deteriorated and demised on postoperative day 69.

Robotic surgery theoretically retains the advantages of the laparoscopic approach in terms of smaller surgical scars, faster recovery, with the additional advantage of stable articulating instruments coupled with a magnified 3D high-definition view.1,9 The main theoretical advantage of the robotic arms is the increased dexterity from the patented Endowrist technology.

During MIDP, the increased dexterity of the robotic arms has been shown to facilitate suturing and fine dissection in tight spaces allowing for more precise dissection of the splenic vessels from the pancreatic parenchyma.2,11,12,24 These advantages have been shown to enable surgeons to perform splenic vessel preservation during MIDP.1,2,10,14,24-26 The results of our study also seem to support this hypothesis. In this study, patients who underwent RDP had a significantly higher splenic preservation rate and splenic vessel preservation rate. It is important to add that the decision for splenic preservation, however, is also dependent on the preoperative indications for DP and individual surgeon preference. Indications for DP associated with malignancy may necessitate splenic resection for better oncological outcomes. Nonetheless, subgroup analysis of only benign/premalignant tumors in this study still demonstrated significantly higher rates of splenic preservation and splenic vessel preservation in the RDP group. The RDP group also had a significantly higher rate of subtotal resection and tumor located close to major vessel compared to LDP. Nonetheless, it is important to highlight that selection bias whereby surgeons may have preferred the robotic platform for patients planned for splenic preservation, may have also accounted for the higher spleen-preservation rate.24 Other confounding factors such as location of tumor (proximity to splenic hilum) may also affect the surgeon’s decision to attempt splenic preservation.

Another postulated advantage of RDP is its lower conversion rate to open surgery compared to LDP.2,10,14,24,25 This is because robotic assistance potentially provides technical advantages such as motion scaling and stabilization as well as reduced operator fatigue, which facilitates hemostasis and control of the vascular structures surrounding the pancreas.24 In our study, common indications for conversion to open surgery include intraoperative bleeding and tumor extension. These intraoperative complications could be better controlled with robotic surgery, reducing the need for open conversion. Nonetheless, while our results show that the rate of conversion tended to be lower for RDP than LDP (3.7% vs. 14.7%, p=0.175), this difference was not statistically significant. Possible confounding factors such as different stages of learning curve and different surgeons’ experience with minimally invasive surgery may also have contributed to these findings. Of note, RDP was only adopted only during the latter study period (2013-2019) whereby our institution already had prior experience with LDP. This important confounding factor likely partially contributed to the superior results observed with RDP as surgeons in our institution had already overcome part of the learning curve for MIDP via performing LDP before embarking on RDP.27,28 It is well-known from the literature that the open conversion rate of MIDP is higher during a surgeon’s initial learning curve.29

In this study, subtotal pancreatectomy was performed significantly more frequently for tumors located in the neck or body via the robotic approach. Some surgeons may propose central pancreatectomy as a parenchyma- saving approach for these tumors especially when these tumors are not suggestive of invasive cancer.30,31 However, in our practice we prefer to perform left-sided pancreatectomy over central pancreatectomy for tumors in these locations as despite the advantages of preserving pancreatic endocrine and exocrine function in the long-term, central pancreatectomy is associated with a higher short- term risk of major morbidity especially a clinically-significant postoperative pancreatic fistula which may potentially be life-threatening.30,31

A frequent disadvantage of robotic surgery reported by many authors is the longer operation time for RDP compared to LDP.1,2,5,12,14,32 Similarly, our study also demonstrated that the operative time was significantly longer with RDP. The longer operation time with RDP can be attributed to the longer docking time and increased time to perform exchange of instruments which has been shown to be improve when surgeons gain increasing experience with the robotic platform.1,2,5,12,32 Based on current literature, it has been suggested that a surgeon would require 7 to 40 cases to overcome the learning curve for RDP when he/she had no prior experience with robotic surgery.33-35 In our experience, this unavoidable learning phase of RDP may have contributed to the longer operative time. Nonetheless, practice and familiarity with the robotic platform, in conjunction with standardization of the surgical technique are likely to reduce the length of the learning curve for RDP.12,28,35-38 Hence, contrary to most studies, some investigators have demonstrated that RDP is associated with a shorter operating time.8

A significant barrier to robotic surgery today is the cost of adopting the procedure.18,32 In this study, cost was a major factor determining the type of minimally invasive surgery adopted as patients had to pay an additional amount of about S$5000 for robotic assisted procedures.32 While the cost of robotic surgery varies between institutions and countries, it is uniformly higher than conventional laparoscopic surgery. As the cost of purchasing and maintain the robot is also significant, relatively few surgeons globally have regular access to the robotic technology for training, contributing to the lack of familiarity and experience with the system.18,24 Hence, the barrier to introduce robotic surgery to many institutions worldwide is relatively high. However, it is important to note that the costs of robotic systems will likely decrease in the near future with increasing availability and competition in the market.18,24,39

Many investigators have demonstrated the safety and feasibility of RDP in comparison with LDP as the incidence of total postoperative complications were similar between the two.1,2 Similarly, the results of our study showed no significant difference between RDP and LDP in terms of the frequency of total complications, major morbidity, pancreatic fistula, and readmission rate. RDP also did not increase the reoperation rates and length of hospital stay.

The main limitations of the present study are its relatively small sample size and its retrospective nature. Hence, it may be subject to Type 1 or 2 errors. Similarly, various other confounding factors such as operative indications, surgeon experience, and patient preference could have also affected outcomes. Selection bias was also likely a major confounder influencing the study results. Nonetheless, the results of the present study reflect the real-world situation whereby surgeons at our institution tended to select more difficult MIDP such as spleen preserving procedures for RDP.

In conclusion, the findings of this study suggest that both RDP and LDP can be safely adopted. The use of RDP appeared to be complementary to LDP in our institution, allowing us to expand our indications for MIDP to more technically difficult procedures such as spleen-saving pancreatectomies with comparable postoperative outcomes.