Background
Distal pancreatectomy (DP) is the mainstay surgical procedure for the treatment of body-tail tumors of the pancreas [
1]. This type of surgery, generally performed through an open access, a fairly common but potentially demanding procedure, is still burdened with a significant morbidity and mortality up of 5% [
2,
3].
Laparoscopic distal pancreatectomy (LDP) is a relatively new procedure as compared with the well-established open distal pancreatectomy [
4,
5]. The first LDP was in fact performed by Cuscheri in 1996 [
6]. Since many authors still consider LDP to be a complex operation because of technical problems linked to the vascular control and dissection of the pancreatic gland that is deeply located in the retroperitoneum, this has resulted in a delay in the spread of LDP when compared to other mini-invasive surgical operations. Thanks to the improvement of technology and the experience gained in laparoscopic surgery, it has been shown that LDP has achieved oncological results comparable to open surgery, with an overlapping rate of morbidity, but with the advantage of small surgical incisions, shorter hospital stay and faster recovery [
7‐
10].
The exceptional development of computer technology and its consequent biomedical applications have enabled the creation of robotic surgery. Robotic distal pancreatectomy (RDP) is the most recent frontier of minimally invasive surgery applied to the surgical treatment of pancreatic tumors [
11,
12]. RDP was first performed by Melvin in 2003 [
13].
Robotic surgery has theoretically made it possible to overcome the disadvantages of the laparoscopic approach to the pancreas. In fact, it allows optimal viewing through a three dimensional high definition surgical view, tremor filtration, large range of motion due to an internal articulated endo-wrist, all associated with remarkable ergonomics for the surgeon who performs the procedure [
14].
Nevertheless, robotic procedures seem to be longer and have higher costs without a clear advantage in terms of surgical and oncologic outcomes [
14,
15]. No randomized controlled trials (RCTs) comparing RDP and LDP have been published on this issue, only retrospective studies [
16‐
26]. Moreover, none of these has reached a uniform conclusion in terms of efficacy and safety [
27]. We therefore performed a systematic review and meta-analysis in order to compare the results of laparoscopic vs robotic distal pancreatectomy.
Discussion
This meta-analysis demonstrates the safety and feasibility of the robotic approach to distal pancreatectomy. Specifically, the results of our study reveal that RDP does not increase the rate of post-operative complications, is associated to higher rate of spleen preservation, reduces hospital stay and decreases conversion rate.
Many studies of minimally invasive distal pancreatectomy have been published in the literature, highlighting the increasing surgical community interest in this new technique [
33,
34].
Several studies have compared open versus laparoscopic distal pancreatectomy, demonstrating the superiority of the latter in terms of less blood loss, faster recovery and less hospital stay [
10,
35‐
37].
Robotic surgery is the latest development of mini-invasive surgery of the pancreas. This technology maintains the advantages of laparoscopic technique in terms of smaller surgical scars and faster functional recovery, but adds the specific advantages of robotic surgery; in fact, thanks to the stability of articulated instruments and magnification of the 3D high definition view, the robot allows more complex surgical operations to be performed. This added value of RDP could increase the chance to increase the rate of spleen preservation [
38,
39].
This meta-analysis shows that the RDP increases the rate of splenic preservation; in fact, 7 studies indicated a better spleen preservation rate through robotic surgery. The preservation of the spleen has been shown to be important in preventing postoperative complications and particularly the overwhelming post-splenectomy infection syndrome. The preservation of the spleen, however, depends not only on technical factors but primarily on the indication for pancreatectomy. In fact, malignant tumors are not an indication for the conservation of the spleen, which is instead generally taken into account for benign or neuroendocrine tumors [
40]. Two spleen-preservation surgical techniques have been described: the Kimura [
41] and the Warshaw method [
42]. In the Kimura’s technique the artery and splenic vein are skeletonized and preserved in order to maintain the vascular flow to the spleen. The Warshaw method consists in the section of splenic vessels while preserving short gastric vessels and left gastroepiplonic artery, which provide adequate vascular flow to the spleen. This second technique seems to increase the risk of spleen infarction. The studies considered in our review do not provide the details of the surgical technique used to preserve the spleen and therefore a comparison between the two methods has not been performed [
43].
With regard to overall postoperative complications, these were similar between two groups. The most frequently reported complication was intra-abdominal fluid collection. However, severe complications, defined as Dindo-Clavien ≥ 3, were similar in the two groups, as was the reported mortality.
The pancreatic fistula is still the Achilles heel of pancreatic surgery [
44‐
46]. This complication remains a very serious problem because it increases morbidity and lengthens hospital stay. Regardless of the technique used to cut and close the pancreatic stump, the incidence of postoperative pancreatic fistula varies from 0 to 47% [
47]. A recent meta-analysis compared different methods of treating pancreatic parenchyma after distal pancreatectomy, but none of the techniques used was superior to the others in reducing the incidence of pancreatic fistula [
48]. In this meta-analysis, nine studies compared the rate of pancreatic fistula between RDP and LDP failing to show any significant differences. In particular, the rate of severe pancreatic fistulas grade B / C was not statistically different between the two groups.
Blood transfusion during surgery for malignant disease is associated with an increased risk of long-term relapse [
49]. In the meta-analysis we did not observe statistically significant differences in the rate of blood transfusions between the two groups.
In relation to oncological parameters, we did not observe significant differences in the considered studies. It was interesting to note that the surgical margins were negative (R0) with a near 100% rate in the two groups and good lymphadenectomy was performed in both groups. However, no indication was provided by the authors regarding chemo-radiotherapy treatments with adjuvant or neoadjuvant purposes. No specific data were also available regarding disease free survival and tumor recurrence. Therefore it is not possible to draw final conclusion on the oncological adequacy of the robotic approach in this type of surgery.
Since minimally invasive surgery is typically associated with a faster recovery, the length of hospital stay is a very important index in the evaluation of this type of surgical approach [
38,
50].
A shorter hospital stay was observed in the RDP group in our study. This result could be an argument in favor of robotic surgery in reducing the overall impact of the cost, which is still considered very high by several authors. Each robotic procedure generally costs from 1000 to 3000 dollars more than a laparoscopic procedure. Our meta-analysis shows that the robotic procedure is more expensive than the laparoscopic one. However, in calculating the cost of the operation Waters et al. [
26] took into account the associated cost of the hospital stay. In this case, robotic surgery showed a greater economic advantage over laparoscopic surgery with an estimated cost of 10,588 and 12,986 dollars respectively for the RDP and the LDP group. It should be noted also that prices often vary considerably among the different surgical centers, even in the same country, so the this comparison may be misleading and at risk of bias.
Our systematic review summarizes most of the available evidence in this context. However, it has some limitations. Although most of the included studies showed a high methodological quality according to the Newcastle-Ottawa scale, the studies were retrospective and not randomized. The absence of randomization and the retrospective nature involves some structural bias that could lead to inaccurate or incorrect conclusions. Further prospective randomized studies are therefore needed to understand which of the two methods is superior to the other in terms of cancer, complications and long-term results.