Comparison of short outcomes between laparoscopic and experienced robotic gastrectomy: A meta-analysis and systematic review.

OBJECTIVE: The purpose of this meta-analysis is to compare the short-term outcomes between experienced robotic gastrectomy (RG) and laparoscopic gastrectomy (LG).
MATERIALS AND METHODS: We searched the PubMed, Springer Link, Elsevier, and Embase databases for articles published in English before June 2015 using an electronic literature search and including cross-referenced articles. Three studies were eligible for the meta-analysis. The outcomes evaluated were operation time, estimated blood loss, harvested lymph nodes, complication, and postoperative hospital stay.
RESULTS: Of a total of 562 patients, 165 underwent RG and 397 underwent LG. Operation time was significantly longer in the RG group [weighted mean difference (WMD): 21.49, 95% confidence interval (CI): 12.48-30.50, P< 0.00001). Estimated blood loss, harvested lymph nodes, complication, and postoperative hospital stay were similar between the two groups.
CONCLUSION: Experienced RG has similar short-term outcomes to LG that is performed by sophisticated laparoscopic surgeons, except for operation time.

INTRODUCTION

Laparoscopic surgery was first reported in 1988, and has been widely used around the world.[1] Laparoscopic radical gastrectomy was first reported by the Japanese scholar Kitano in 1994.[2] Laparoscopic gastrectomy (LG) has proven beneficial in terms of gastrointestinal function recovery, postoperative pain, return to normal activity and hospital stay, more beneficial with open surgery.[34] More and more reports reveal that LG could have short-term and long-term outcomes equivalent to open operation.[56] Although laparoscopic surgery has a number of advantages, there are also disadvantages, such as the possibility of tremor, the surgeon's postural discomfort, two-dimensional images, a long learning curve, and low sensitivity of surgical instruments. Accordingly, the invention of the robotic Da Vinci Surgical System (American company Intuitive Surgical) solved this problem well, with three-dimensional images, no tremor, convenient movements of the robotic arm, and ambidextrous capability.[78] Robot-assisted gastrectomy was first reported in 2002;[9] since then, robotic gastrectomy (RG) for gastric cancer has undergone rapid development in Korea, Japan, Italy and other countries.[101112] The feasibility and safety of the Da Vinci robotic system in the surgical treatment of gastric cancer have been reported on by many scholars.[13]

In evidence-based medicine, several meta-analyses have compared the feasibility and efficacy of RG to that of LG.[141516] However, studies included in these publications contain cases treated during the training or learning period for RG, thus increasing the risk of bias and precluding fair and equal statistical results for comparison with LG performed by an experienced surgeon. Park et al.[17] have proved that 20 cases of RG by experienced laparoscopic surgeons are sufficient to overcome the learning curve and show consistent performance. Thus, we conducted a meta-analysis of experienced RG compared with LG.

MATERIALS AND METHODS

Search strategy

We searched the PubMed, Springer Link, Elsevier, and Embase databases for articles published in English before June 2015 using an electronic literature search and including cross-referenced articles. The search used the following terms: ‘robotic gastrectomy’, ‘gastric neoplasms’, ‘robot-assisted gastrectomy’, ‘laproscopic gastrectomy’, and ‘gastrectomy’. We also evaluated the references of all relevant articles to find other, related studies.

Study selection

Inclusion criteria for articles were as follows:

They had to be full articles published in English;

They had to be comparative studies between RG and LG;

Surgeons who carried out the RG were required to have experience with at least 20 cases of RG;

Only the updates or the largest report was considered when multiple publications by the same research group were found, to avoid double-counting subjects;

Each study reported at least one of the following clinical outcomes: Operation time, estimated blood loss, harvested lymph nodes, postoperative hospital stay, and complication.

Exclusion criteria for articles were as follows:

Articles were not published in English;

Studies were not comparative studies between RG and LG;

Studies did not focus on gastric cancer surgery;

Studies did not report experienced RG;

None of the clinical outcomes we considered requisite were present.

Evaluation of methodological quality and risk of bias

The methodological quality and bias of included studies were assessed using the tools recommended by the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0. This ‘risk of bias’ assessment tool includes six aspects: Random sequence generation, allocation concealment, blinding of participants and personnel, incomplete outcome data, selective reporting, and other bias. The quality evaluation and cross-checking were conducted independently by two researchers, and decisions were made through discussion, or by the third researcher in case of disagreement.

Statistical analysis

All available trials with reporting data were summarised. Revman 5.3 (Download from “Cochrane Library”, http://tech.cochrane.org/home) was used for statistical analysis of the data. We have reported all continuous variables as weighted mean difference (WMD) and standard deviation (SD). For dichotomous outcomes, we used the odds ratios (ORs) with 95% confidence intervals (CIs). The χ2 statistic was used to assess heterogeneity among the trials and the I2 statistic was used to assess the extent of inconsistency; significant heterogeneity was present when P < 0.05 or I2 > 70%. A fixed-effect model was used if there was no significant heterogeneity, otherwise a random-effect model was used.

RESULTS

Selected studies

We initially identified 163 publications through searching the literature databases and cited references; 143 of them were excluded after reading the abstracts because they were not relevant to the proposed interventions. After the full-text articles were screened, 15 publications were found to not report data about experienced RG particularly. Another two publications[1819] reported experienced RG after 12 and 15 cases of initial experience, respectively, thus they were excluded. Finally, three studies[202122] were deemed eligible for the meta-analysis. Figure 1 shows the selection process from initial review to inclusion in our meta-analysis. Table 1 shows the characteristics of the included studies. We noted no difference between the two groups in terms of age (P = 0.18), and no difference in BMI (P = 0.97) either. Regarding the comparison of early-stage gastric cancer, only two studies[2021] reported detailed data, and there was no obvious statistical difference (P = 0.05). However, Kang's study merely reported the staging of the RG group with 82, 11, and 7 patients in stages I, II, and III, respectively.

Figure 1

Flow chart showing systematic review search results

Table 1

Characteristics of studies included in the meta-analysis

Study quality

Figure 2 shows the methodological quality of the three included studies, which was assessed by using the Cochrane Handbook 5.1.0. Because of the informed consent required for operation, none of these three publications adopted a blind method. Furthermore, none of the papers adequately described allocation concealment.

Figure 2

Quality evaluation of studies in the meta-analysis

Operative outcomes

All of three studies reported operation time. A fixed-effect model was used because heterogeneity was not observed in the three studies (I2 = 57%, P = 0.10). The operation time was longer for RG than for LG (WMD: 21.49, 95% CI: 12.48-30.50, P < 0.00001) [Table 2]. Estimated blood loss was reported in all three studies. Because of the significant heterogeneity (I2 = 94%, P < 0.00001), a random-effects model was used. Pooled analysis of the data revealed that there was no significant difference between the two groups (WMD: −16.60, 95% CI: −61.31 to 28.11, P = 0.47) [Table 3]. Two studies reported on harvested lymph nodes. Heterogeneity was not observed ((I2 = 0%, P = 0.83), therefore a fixed-effect model was used. We noted no difference between the two groups (WMD: −0.23, 95% CI: −3.80 to 3.35, P = 0.90) [Table 4].

Table 2

Operative time

Table 3

Estimated blood loss

Table 4

Harvested lymph nodes

Short-term outcomes

With regard to hospital stay, the analysis did not reveal significant heterogeneity (I2 = 0%, P = 0.47), thus a fixed-effect model was used. The three groups showed no statistical difference (WMD: 0.19, 95% CI: -0.91 to 1.30, P = 0.74) [Table 5]. Thirty-two cases of complications occurred in 165 patients in the RG group, and 62 cases of complications occurred in 397 patients in the LG group; the difference was not statistically significant (OR: 1.37, 95% CI: 0.81-2.30, P = 0.24) [Table 6].

Table 5

Hospital stay

Table 6

Complication

DISCUSSION

Because of the minimal trauma, less blood loss, higher quality of life after operation, light pain and quick recovery associated with it, minimally invasive technique has been used more and more frequently. In gastrointestinal surgery, this technique is used not only for early gastric cancer, but also in cases of advanced gastric cancer,[2324] and could reach the same long-term outcomes as open surgery.[2526] However, with two-dimensional imaging, it is difficult for laparoscopy to complete the reconstruction of the digestive tract, so a 10-cm abdominal incision is needed to finish it, obviously impacting postoperative recovery and prolonging the hospital stay. Robotic surgery is superior to laparoscopic surgery in that it has tremor filtration, stereoscopic vision, wristed instruments and the ability to scale motion.[27] These features improve a surgeon's dexterity and allow intracorporeal anastomoses and precise lymph node dissection.[28] The number of retrieved lymph nodes directly impacts the recurrence and metastasis of carcinoma. In this meta-analysis, we gained a similar result for RG and LG in harvested lymph nodes (WMD: 0.23, P = 0.90). The reason for this may be that the surgeons who conducted RG in the included studies were very experienced in laparoscopic procedures, which may have reduced the benefit they derived from utilising the robotic system. Some other studies show that RG is easier and more accurate in lymph node exposure, identification and retrieve in operation,[29] even more so in lymph node dissection.[30]

This meta-analysis included three studies with a total of 165 patients who had undergone RG and 397 patients who had undergone LG. All these three studies were published recently, and could commendably reflect the current evidence and reduce the bias from the initial learning experience. According to the studies included in the meta-analysis, operation time in RG was longer than in LG (WMD: 21.49, P < 0.00001): All the operations reported in these studies were completed by surgeons who had finished a learning curve of at least 20 cases. Studies previously also showed that more time was needed for RG.[3132] The reason might be that the robotic Da Vinci Surgical System is a kind of precision instrument: The time for setting and docking is relatively longer than for a laparoscopic system, and more time would be required to fix or restart the system if there was an intraoperative robotic breakdown. The changing of the surgical instrument would also need more time than with laparoscopy.

The results in our analysis revealed that RG and LG had similar estimated blood loss (WMD: -16.60, P = 0.47). Theoretically, with the three-dimensional images, better zoom function and more precise dissection, the RG group should reveal less blood loss than the LG group. As there have been only three reported cases of experienced RG after at least 20 cases of learning curve up to now, however, significant heterogeneity was noted (I2 = 94%, P < 0.00001) in these three studies. Huang's studies reported that RG and LG showed no statistical difference in estimated blood loss, but from the forest plot, we can see that most of the 95% CI was on the right side of the invalid line; meanwhile, Kang's studies reported that the estimated blood loss was obviously less for RG than for LG. In another allied meta-analysis,[14] it was indicated that there was less blood loss in the RG group than in the LG group.

Complications form an important indicator of short-term outcomes as they directly influence the postoperative hospital stay. Analysis of the pooled data found that the total complication rates were similar between RG and LG (OR: 1.37, P = 0.24). Regarding hospital stay, the analysis did not reveal difference there, either (WMD: 0.19, P = 0.74). These results indicate that RG is as safe and effective as LG.

CONCLUSION

In conclusion, our meta-analysis showed that experienced RG could reach short-term outcomes, such as in estimated blood loss, harvested lymph nodes, complications and postoperative hospital stay, similar to LG carried out by sophisticated laparoscopic surgeons. However, in terms of operative time, RG showed a longer duration than LG. RG procedures need to be performed with much more experience for further study on short-term and long-term outcomes.

Financial Support and Sponsorship

Nil.

Conflicts of Interest

There are no conflicts of interest.