Asian Journal of Surgery xxx (xxxx) xxx

Contents lists available at ScienceDirect

Asian Journal of Surgery
journal homepage: www.e-asianjournalsurgery.com

Original Article

Robotic vs. laparoscopic distal gastrectomy for gastric cancer: A
propensity score-matched retrospective comparative study at a single
institution
Masaki Kitazono a, *, Makoto Fujita b, Shuichiro Uchiyama a, Mayumi Eguchi a,
Naotaka Ikeda aab

Department of Surgery, Nanpuh Hospital, Kagoshima-city, 892-8512, Japan
Division of Medical Support, Nanpuh Hospital, Kagoshima-city, 892-8512, Japana r t i c l e i n f o

a b s t r a c t

Article history:
Received 13 September 2023
Received in revised form
1 November 2023
Accepted 6 March 2024
Available online xxx

Background: Although robotic surgery is becoming more widespread worldwide, it is still in its infancy.
This study aimed to conﬁrm the safety and feasibility of the induction of robotic-assisted gastric surgery
at a local hospital.
Methods: For ﬁve years, between 2016 and 2020, 42 laparoscopic and 71 robotic distal gastrectomies
were performed at the same institution. Patients diagnosed with gastric cancer were retrieved from thedatabase. Propensity score matching was performed based on covariates such as Age, Sex, BMI, theAmerican Society of Anesthesiologists Physical Status, Tumor Location, pT, and pN. Clinicopathologicalcharacteristics, surgical performance, postoperative outcomes, and pathological data were retrospectively collected and compared by the Chi-square test, the Fisher's exact test, the Student's t-test, and theManneWhitney U test.
Results: Billroth II reconstruction was often selected for the robotic group more than the laparoscopic
group (59.4% and 15.6%, respectively). In addition, the number of lymph nodes harvested after D2
dissection tended to be more signiﬁcant in the robotic group than in the laparoscopic group (52.1 ± 7.6
and 29.1 ± 3.7, respectively; p ¼ 0.00934). The mean operative time was 271.4 ± 10.5 min for the robotic
group and 220.8 ± 12.3 min for the laparoscopic group (p ¼ 0.00005). There were no differences in shortterm clinical outcomes between the two groups.
Conclusions: Although a single-center, small comparative study, the results showed that the robotic
surgery group was not inferior to the laparoscopic group in feasibility and safety. Moreover, robotic
surgery enables harvesting a higher number of lymph nodes, which may be more advantageous thanlaparoscopic surgery. This study also showed that as the surgeon gains experience with robotic surgery,its operative time becomes signiﬁcantly shorter.
© 2024 Asian Surgical Association and Taiwan Robotic Surgery Association. Publishing services by
Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/
licenses/by-nc-nd/4.0/).

Keywords:
Gastric cancer
Laparoscopic surgery
Lymphadenectomy
Robotic surgery

1. Introduction
Gastric cancer, which affected more than 1 million people in2018, is a signiﬁcant burden on the healthcare system.1 Incidence
varies widely by continent, with the Far East having the highest
incidence. Moreover, gastric cancer kills 50,000 people annually in* Corresponding author. Public Interest Incorporated Association, Kagoshima
Kyosaikai, Nanpuh Hospital, 14-3, Nagata-cho, Kagoshima-city, Kagoshima Pref,
892-8512, Japan.
E-mail address: opera_2@hotmail.com (M. Kitazono).

Japan, making it the third deadliest cancer by the number of deaths.
Currently, treatment for gastric cancer includes anticancer
drugs, surgery, and radiation therapy. Among these, surgical therapy is undeniably the most effective for gastric cancer. Radical
gastrectomy with regional lymph node dissection is still considered
the only curative treatment for gastric cancer.2,3 In Japan, the demand for minimally invasive surgery has increased dramatically inrecent years as the early gastric cancer diagnosis rate has exceeded
50%.4 Minimally invasive surgery for gastric cancer has evolved
rapidly. It has increased in popularity during the last two decades,
mainly in the Far East and for patients with early-stage tumors.5,6

https://doi.org/10.1016/j.asjsur.2024.03.086
1015-9584/© 2024 Asian Surgical Association and Taiwan Robotic Surgery Association. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NCND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Please cite this article as: M. Kitazono, M. Fujita, S. Uchiyama et al., Robotic vs. laparoscopic distal gastrectomy for gastric cancer: A propensity
score-matched retrospective comparative study at a single institution, Asian Journal of Surgery, https://doi.org/10.1016/j.asjsur.2024.03.086

M. Kitazono, M. Fujita, S. Uchiyama et al.

Asian Journal of Surgery xxx (xxxx) xxx

Gastric surgery is one of the most relevant and developed ﬁelds ofminimally invasive surgery.7 In terms of minimally invasive surgery, there are laparoscopic and robotic surgeries, but their merits
and demerits are still to be clariﬁed.
While laparoscopic surgery has spread worldwide, robotic surgery is still in its infancy. Robotic-assisted gastrectomy (RAG) for
gastric cancer was ﬁrst reported in 2002.8 According to Lim SH et al,
the introduction of RAG has increased exponentially. However, thisrepresents about 2% of all gastrectomies performed in Korea andonly about 4% of all robotic surgeries performed annually.9,10 Researchers and surgeons are focusing on applying advanced robotic
technology to gastrectomy.
Our aim with this study is to examine our initial use of robotic
distal gastrectomy and compare the surgical performance andpostoperative outcomes of laparoscopic and robotic distal gastrectomy for gastric cancer.

Fig. 1. Port positioning and instrument installation for robotic distal gastrectomy.

2. Methods
2.1. Patients
A total of 136 patients underwent distal gastrectomy (DG) between 2016 and 2020 at Nanpuh Hospital, Japan. Invalid data suchas open distal gastrectomy and lack of clinical data were excluded.
Forty-two laparoscopic distal gastrectomies (LDG) and 71 robotic
distal gastrectomies (RDG) for gastric cancer were included in the
study. The clinicopathological characteristics, surgical performance, postoperative outcomes, and pathological data between
these two groups of patients were retrospectively collected andcompared.
Prior to the commencement of the study, all patients underwent
a thorough screening process. This involved the implementation ofa standard protocol that encompassed upper digestive endoscopy,
along with gastric biopsy and computed tomography of theabdomen and chest. We ensured that all patients were thoroughly
informed about the investigation and provided their written consent as well. Our actions were in strict accordance with the ethicalcommittee of our hospital and fully compliant with the Helsinki
Declaration.
Comprehensive patient-related information was meticulously
gathered, covering a range of crucial factors such as age, sex, BMI,
the American Society of Anesthesiologists Physical Status (ASA-PS),
tumor location, pathological ﬁndings, as well as surgical outcomes,
which incorporated type of reconstructions, blood loss, bloodtransfusion, operative time, open conversion, lymph node dissection, number of lymph nodes harvested after D2 dissection, andshort-term clinical outcomes such as time to ﬁrst oral feeding,surgery-related complications, reoperation, mortality and postoperative length of stay.
Tumor location was precisely categorized as either the middle or
lower third, and the type of lymph node removal was determinedbased on the lymph node classiﬁcation provided by the Japanese
Gastric Cancer Association.11 Tumors were classiﬁed according to
the 7th edition of the AJCC/TNM tumor staging.12

Fig. 2. Flowchart of patient data collected in the study.

transumbilical incision for the camera port. Once the pneumoperitoneum was established, three 8-mm trocars were inserted forthe robotic arms. One was placed in the right lumbar, and two wereplaced in the left (Fig. 1). Two 12-mm ports for an assistant werealso inserted in the right lumbar and Umbilical region down leftfrom the umbilicus for surgical gauze, suctioning, or removal of the

2.2. Operative technique2.2.1. Setup for robotic distal gastrectomy
In RDG, all robotic surgeries were performed using the da Vinci
Xi system (Intuitive Surgical, Sunnyvale, CA, USA). The preparation
process for RDG surgery closely resembles that of LDG surgery,except for using robotic ports and instruments. The patient wasplaced in the supine and reverse Trendelenburg position, with eachleg elevated approximately 13 , and abducted while under generalanesthesia. An 8-mm trocar was inserted through theFig. 3. Propensity score analysis before and after pair-matching (Robotic vs.
Laparoscopic).
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Asian Journal of Surgery xxx (xxxx) xxx

2.2.2. The procedures of distal gastrectomy
All gastrectomies were performed according to the standard ofradical gastrectomy based on the Japanese Gastric Cancer treatment guidelines.13 The procedures employed during RDG are notdifferent from those of LDG except for articulating robotic instruments. The LDG surgical technique involves placing four trocars
two 12-mm trocars, and two 5-mm trocars in the usual positions. In
cases where Billroth-I reconstruction was feasible, a Delta-shaped
anastomosis was utilized. When it was not possible, either
Billroth-II or Roux-en-Y reconstruction was employed. Following
the reconstruction, a single abdominal drainage tube was inserted
into the left subphrenic cavity.
2.3. Data validation and statistical analysis
Fig. 2 shows the ﬂow chart of patient data collected in this study.
One hundred thirty-six patients were retrieved, including 71 patients who underwent robotic distal gastrectomy. Propensity scorematching (PSM) was performed to reduce bias between two groups
based on covariates such as Age, Sex, BMI, ASA-PS, Tumor Location,
pT, and pN. After A 1:1 nearest-neighbor matching algorithm with
an optimal caliper width of 0.20 without replacement, 32 pairs
were generated (64 patients) for the comparison between LDG and
RDG. Furthermore, we also compared RDG performed between theﬁrst period (2016e2018) and the second period (2019e2020) toanalyze time-related changes in surgical outcomes of RDG. The ﬁrst
and second periods groups comprised 32 and 39 cases, respectively,
and 21 pairs (42 patients) were generated after PSM. Figs. 3 and 4shows the propensity score between the two groups for eachFig. 4. Propensity score analysis before and after pair-matching (2016e2018 vs.
2019e2020).

small resected tissue during operations. During the surgery, an air
seal port and Cadiere forceps were held in the patient's ﬁrst roboticarm on the right side. On the left side, a Maryland bipolar forceps, aCadiere forceps and Vessel Sealer system were held in the third andfourth arms, respectively.

Table 1
Summary of patients and disease characteristics before and after matching (LDG vs. RDG).
Before PSM

AgeMean ± SEM
Median(IQR)
Sex
Male
FemaleBMI
Mean ± SEM
Median(IQR)
ASA-PSI
II
Tumor Location
Middle third
Lower third
Tumor size(cm)Mean ± SEM
Median(IQR)
pStage
I
II
III
pT
T1
T2
T3
T4
pN
N0
N1
N2
N3

After PSM

LDG (n ¼ 42)

RDG (n ¼ 71)

p-value

LDG (n ¼ 32)

RDG (n ¼ 32)

p-value

70.2 ± 1.8
73.0 (61.0e81.0)

64.3 ± 1.4
67.0 (59.0e73.0)

0.01108 *69.1 ± 2.0
71.0 (60.0e79.5)

67.6 ± 1.6
70.0 (64.0e74.0)

0.57189

31 (73.8%)
11 (26.2%)

41 (57.7%)
30 (42.3%)

0.08613

23 (71.9%)9 (28.1%)

21 (65.6%)
11 (34.4%)

0.58964

22.899 ± 0.611
22.630 (20.670e25.360)

23.380 ± 0.402
23.390 (20.850e25.850)

0.49453

23.408 ± 0.737
23.160 (21.475e26.330)

23.735 ± 0.606
23.820 (21.330e25.845)

0.733213 (7.1%)34 (81.0%)
5 (11.9%)

16 (22.5%)
54 (76.1%)
1 (1.4%)0.0043 **3 (9.4%)28 (87.5%)
1 (3.1%)1 (3.1%)30 (93.8%)
1 (3.1%)0.4102330 (71.4%)
12 (28.6%)

45 (63.4%)
26 (36.6%)

0.381524 (75.0%)
8 (25.0%)

22 (68.8%)
10 (31.3%)

0.57818

34.7 ± 2.6
33.0 (24.0e40.0)

30.9 ± 2.1
27.0 (17.3e42.3)

0.26705

34.4 ± 3.1
33.0 (22.5e39.0)

34.9 ± 3.5
31.0 (18.0e45.5)

0.91549

33 (78.6%)
4 (9.5%)5 (11.9%)50 (70.4%)
15 (21.1%)
6 (8.5%)0.46081

26 (81.3%)
3 (9.4%)3 (9.4%)22 (68.8%)
8 (25.0%)
2 (6.3%)0.3291427 (64.3%)
7 (16.7%)
5 (11.9%)
3 (7.1%)49 (69.0%)
6 (8.5%)12 (16.9%)
4 (5.6%)0.73956

23 (71.9%)
3 (9.4%)5 (15.6%)
1 (3.1%)22 (68.8%)
3 (9.4%)5 (15.6%)2 (6.3%)0.73864

33 (78.6%)
4 (9.5%)3 (7.1%)2 (4.8%)51 (71.8%)
10 (14.1%)
8 (11.3%)
2 (2.8%)0.48258

26 (81.3%)
3 (9.4%)2 (6.3%)1 (3.1%)25 (78.1%)
3 (9.4%)2 (6.3%)2 (6.3%)0.72348

PSM¼Propensity score matching; LDG ¼ laparoscopic distal gastrectomy; RDG ¼ robot-assisted distal gastrectomy.
*P < 0.05 indicates statistical signiﬁcance (**P < 0.01, and ***P < 0.001).
3

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Asian Journal of Surgery xxx (xxxx) xxx

Table 2
Summary of surgical outcomes before and after matching (LDG vs. RDG).
Before PSM
LDG (n ¼ 42)

After PSM
RDG (n ¼ 71)

Type of reconstruction
Billroth-I
25 (59.5%)
28 (39.4%)
Billroth-II
9 (21.4%)
40 (56.3%)
Roux-en-Y
8 (19.0%)
3 (4.2%)
Blood loss(ml)Mean ± SEM
55.6 ± 10.8
50.3 ± 6.6Median(IQR)
30.0 (15.0e70.0)
30.0 (20.0e60.0)
Blood transfusion
2 (4.8)1 (1.4)
Operative time(min)Mean ± SEM
220.9 ± 9.9
269.3 ± 6.6Median(IQR)
218.0 (185.0e242.0)
262.0 (236.0e304.5)
Open Conversion
none
none
Lymph node dissection
D1
6 (14.3%)
16 (22.5%)
D1þ
17 (40.5%)
30 (42.3%)
D2
19 (45.2%)
25 (35.2%)
Number of lymph nodes harvested after D2 dissection
Mean ± SEM
30.4 ± 3.3
42.2 ± 5.0
Median(IQR)
30.0 (19.3e40.3)
37.0 (26.8e47.0)

p-value

LDG (n ¼ 32)

RDG (n ¼ 32)

p-value

0.0004 ***

21 (65.6%)
5 (15.6%)
6 (18.8%)

12 (37.5%)
19 (59.4%)
1 (3.1%)0.00083 ***0.9619454.2 ± 11.4
35.0 (10.0e70.0)
2 (6.3)56.3 ± 11.8
30.0 (17.5e67.5)
1 (3.1)0.94088220.8 ± 12.3
215.5 (184.0e239.5)
none

271.4 ± 10.5
262.5 (237.0e312.0)
none

0.00259 **

0.444

4 (12.5%)
13 (40.6%)
15 (46.9%)

8 (25.0%)
10 (31.3%)
14 (43.8%)

0.414970.07072

29.1 ± 3.7
30.0 (16.8e40.3)

52.1 ± 7.6
44.5 (35.0e58.0)

0.00934 **0.554230.00005 ***e

1.00000e

PSM¼Propensity score matching; LDG ¼ laparoscopic distal gastrectomy; RDG ¼ robot-assisted distal gastrectomy.
*P < 0.05 indicates statistical signiﬁcance (**P < 0.01, and ***P < 0.001).

mean of operative time was signiﬁcantly longer in RDG group(271.4 ± 10.5 vs. 220.8 ± 12.3, p ¼ 0.00259; Fig. 5), and a more signiﬁcant number of lymph nodes harvested after D2 dissection was
retrieved in the RDG group (52.1 ± 7.6 vs. 29.1 ± 3.7, p ¼ 0.00934;
Fig. 6). Both groups were similar in blood loss, blood transfusion, andopen conversion. As shown in Table 3, no signiﬁcant differences were
found in short-term clinical outcomes.
As a result of the comparison of RDG performed in the ﬁrst period
and the second period group to analyze the time-related changes,
there was no statistically signiﬁcant difference in the summary ofpatients and disease characteristics between the ﬁrst and the second
period group after PSM (Table 4). In surgical outcomes (Table 5),
Billroth-II (B-II) was performed more with a signiﬁcant difference inthe second period group compared to the ﬁrst period group (71.4%
vs. 33.3%, p ¼ 0.04678), the mean of operative time was signiﬁcantly
shorter in the second period group (244.9.±9.8 vs. 302.5 ± 12.8,

comparison that was balanced after PSM. Categorical variables
were compared using the Chi-square test or the Fisher's exact test.
Quantitative variables were compared using the Student's t-test or
the ManneWhitney U test depending on the result of
KolmogoroveSmirnov Test. P < 0.05 was considered statisticallysigniﬁcant. All statistical analyses were calculated with R Statistical
Software (version 4.2.2; R Foundation for Statistical Computing,
Vienna, Austria) and StatFlex (version 7; Artech Co. Ltd., Fukuoka,
Japan).
3. Results
After PSM, there was no statistically signiﬁcant difference in thesummary of patients and disease characteristics between the LDG
and RDG groups (Table 1). Table 2 shows surgical outcomes. BillrothII (B-II) was performed more in RDG group when compared to LDG
group with a signiﬁcant difference (59.4% vs. 15.6%, p ¼ 0.00083), theFig. 6. Comparison of the number of lymph nodes harvested after D2 dissection between LDG and RDG after PSM.

Fig. 5. Comparison of operative time between LDG and RDG after PSM.
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Asian Journal of Surgery xxx (xxxx) xxx

Table 3
Summary of short-term clinical outcomes before and after matching (LDG vs. RDG).
Before PSM

Time to ﬁrst oral feeding(day)Mean ± SEM
Median(IQR)
Surgery-related complications
Postoperative ileus
Postoperative bleeding
Postoperative bleeding anastomotic ulcer
Postoperative wound infection
Postoperative intra-abdominal abscess
Postoperative anastomotic stenosis
Postoperative pancreatic ﬁstula
Upper gastrointestinal bleeding
Reoperations
Mortality
Postoperative length of stay(day)Mean ± SEM
Median(IQR)

After PSM

LDG (n ¼ 42)

RDG (n ¼ 71)

p-value

LDG (n ¼ 32)

RDG (n ¼ 32)

p-value

4.6 ± 0.8
4.0 (3.0e4.0)

3.6 ± 0.1
3.0 (3.0e4.0)

0.070894.8 ± 1.1
3.5 (3.0e4.0)

3.5 ± 0.1
3.0 (3.0e4.0)

0.255470 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)2 (4.8%)1 (2.4%)1 (2.4%)1 (2.4%)none
none

1 (1.4%)
1 (1.4%)
1 (1.4%)2 (2.8%)3 (4.2%)0 (0.0%)0 (0.0%)0 (0.0%)none
none

0.42884

0 (0.0%)0 (0.0%)0 (0.0%)0 (0.0%)2 (6.3%)0 (0.0%)1 (3.1%)1 (3.1%)none
none

0 (0.0%)1 (3.1%)1 (3.1%)2 (6.3%)1 (3.1%)0 (0.0%)0 (0.0%)0 (0.0%)none
none

0.3849914.6 ± 1.3
11.5 (11.0e16.0)

13.0 ± 0.7
12.0 (10.0e13.8)

0.45391

14.4 ± 1.6
11.0 (10.5e13.5)

13.3 ± 1.3
11.5 (10.0e13.5)

0.69399eeee

PSM¼Propensity score matching; LDG ¼ laparoscopic distal gastrectomy; RDG ¼ robot-assisted distal gastrectomy.
*P < 0.05 indicates statistical signiﬁcance (**P < 0.01, and ***P < 0.001).

several decades.14 Another clear thing is that performing gastriccancer surgery laparoscopically is highly challenging. In particular,
skill is required for lymph node number 6, 8, and 11 dissection andsuture procedures in anastomotic operations.15,16 Therefore, robotic
surgery was introduced to reduce the difﬁculty of operation while
retaining the good points of laparoscopic surgery.
With the development of technology, robotic surgery has
become widely performed in the ﬁeld of urology,17 gynecology,18

p ¼ 0.00092; Fig. 7), and there was no D2 lymph node dissection
performed in the ﬁrst period group. No signiﬁcant differences were
found in short-term clinical outcomes (Table 6).
4. Discussion
The effectiveness and superiority of laparoscopic surgery inclinical practice have been demonstrated by studies over the past

Table 4
Summary of patients and disease characteristics before and after matching (RDG 2016e2018 vs. RDG 2019e2020).
Before PSM

AgeMean ± SEM
Median(IQR)
Sex
Male
FemaleBMI
Mean ± SEM
Median(IQR)
ASA-PS
I
II
III
Tumor Location
Middle third
Lower third
Tumor size(cm)Mean ± SEM
Median(IQR)
pStage
I
II
III
pT
T1
T2
T3
T4
pN
N0
N1
N2
N3

After PSM

RDG 2016e2018 (n ¼ 32)

RDG 2019e2020 (n ¼ 39)

p-value

RDG 2016e2018 (n ¼ 21)

RDG 2019e2020 (n ¼ 21)

p-value59.2 ± 2.1
60.5 (49.5e68.5)

68.5 ± 1.6
70.0 (65.0e74.0)

0.0011 **61.9 ± 2.5
66.0 (56.0e68.3)

64.8 ± 2.4
66.0 (62.8e70.8)

0.41234

19 (59.4%)
13 (40.6%)

22 (56.4%)
17 (43.6%)

0.80132

13 (61.9%)
8 (38.1%)

12 (57.1%)
9 (42.9%)0.75325

23.540 ± 0.708
23.475 (20.780e25.985)

23.248 ± 0.452
23.390 (21.023e25.455)

0.72026

22.734 ± 0.773
23.190 (20.440e25.750)

23.256 ± 0.677
22.980 (20.890e25.580)

0.61417

9 (28.1%)
22 (68.8%)
1 (3.1%)7 (17.9%)32 (82.1%)
0 (0.0%)0.45867

7 (33.3%)
14 (66.7%)
0 (0.0%)4 (19.0%)
17 (81.0%)
0 (0.0%)0.29241

20 (62.5%)
12 (37.5%)

25 (64.1%)
14 (35.9%)

0.88908

14 (66.7%)
7 (33.3%)

14 (66.7%)
7 (33.3%)

1.00000

28.4 ± 2.7
25.0 (17.0e39.0)

32.9 ± 3.2
28.0 (17.3e44.5)

0.30455

29.1 ± 3.1
27.0 (15.8e41.3)

37.4 ± 4.9
32.0 (22.3e46.5)

0.163926 (81.3%)
4 (12.5%)2 (6.3%)24 (61.5%)
11 (28.2%)
4 (10.3%)

0.08322

16 (76.2%)
3 (14.3%)
2 (9.5%)16 (76.2%)
5 (23.8%)
0 (0.0%)0.86545

24 (75.0%)
2 (6.3%)5 (15.6%)
1 (3.1%)25 (64.1%)
4 (10.3%)
7 (17.9%)
3 (7.7%)0.321515 (71.4%)
1 (4.8%)5 (23.8%)
0 (0.0%)16 (76.2%)
0 (0.0%)4 (19.0%)
1 (4.8%)0.85686

28 (87.5)
2 (6.3)1 (3.1)1 (3.1)23 (59.0)
8 (20.5)
7 (17.9)
1 (2.6)0.01054 *

17 (81.0)
2 (9.5)1 (4.8)1 (4.8)18 (85.7)
3 (14.3)
0 (0.0)0 (0.0)0.60019

PSM¼Propensity score matching; LDG ¼ laparoscopic distal gastrectomy; RDG ¼ robot-assisted distal gastrectomy.
*P < 0.05 indicates statistical signiﬁcance (**P < 0.01, and ***P < 0.001).
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Table 5
Summary of surgical outcomes before and after matching (RDG 2016e2018 vs. RDG 2019e2020).
Before PSM
RDG 2016e2018 (n ¼ 32)

After PSM
RDG 2019e2020 (n ¼ 39)

Type of reconstruction
Billroth-I
19 (59.4%)
9 (23.1%)
Billroth-II
11 (34.4%)
29 (74.4%)
Roux-en-Y
2 (6.3%)1 (2.6%)
Blood loss(ml)Mean ± SEM
58.4 ± 10.1
43.7 ± 8.7
Median(IQR)
34.0 (25.0e67.5)
20.0 (15.0e50.0)
Blood transfusion
0 (0.0)1 (2.6)
Operative time(min)Mean ± SEM
301.8 ± 9.4
242.7 ± 6.9Median(IQR)
293.5 (260.5e329.5)
245.0 (211.0e264.5)
Open Conversion
none
none
Lymph node dissection
D1
7 (21.9%)9 (23.1%)
D1þ
25 (78.1%)
5 (12.8%)
D2
0 (0.0%)25 (64.1%)
Number of lymph nodes harvested after D2 dissection
Mean ± SEM
none
42.2 ± 5.0
Median(IQR)
none
37.0 (26.8e47.0)

p-value

RDG 2016e2018 (n ¼ 21)

RDG 2019e2020 (n ¼ 21)

p-value0.0033 **

12 (57.1%)
7 (33.3%)
2 (9.5%)5 (23.8%)
15 (71.4%)
1 (4.8%)0.04678 *0.0503957.0 ± 13.9
30.0 (25.0e56.3)
0 (0.0)37.9 ± 7.1
30.0 (13.8e50.0)
1 (4.8)0.22458302.5 ± 12.8
290.0 (254.0e333.3)
none

244.9 ± 9.8
252.0 (220.5e263.8)
none

0.00092 ***0.00000 ***

4 (19.0%)
17 (81.0%)
0 (0.0%)5 (23.8%)2 (9.5%)14 (66.7%)

0.00000 ***

e

none
none

47.4 ± 8.2
37.5 (34.0e48.0)e

1.00000
0.00000 ***e

1.00000e

PSM¼Propensity score matching; LDG ¼ laparoscopic distal gastrectomy; RDG ¼ robot-assisted distal gastrectomy.
*P < 0.05 indicates statistical signiﬁcance (**P < 0.01, and ***P < 0.001).

general surgery,19 and robotic surgery have become an attractive
option for surgeons. Robotic surgery is classiﬁed as laparoscopic
surgery, but the operation is more straightforward and intuitive.
The forceps used in the robot have a high degree of freedom andprovide smooth movement in situations where precise movement
is required in a narrow surgical ﬁeld or in the vicinity of vital organs. A high-performance camera that projects three-dimensional
images makes it possible to see anatomy that could not be
captured by the naked eye, helping to improve safety and radical
cancer resection. Many studies have shown the feasibility andsafety of robotic gastric surgery, but a clear superiority over laparoscopy has not yet been demonstrated.20e24 No substantial reductions in time to ﬁrst bowel movement or time to ﬁrst oral
nutritional intake. No substantial reduction in hospital stay has
been reported after robotic surgery compared to laparoscopic surgery. Our study also failed to prove the superiority of the robotic
surgery group in short-term clinical outcomes. Why can't we show
the superiority of robotic surgery? Perhaps it is because laparoscopic surgery is already at a sufﬁciently high clinical level. There
are several studies comparing the difference in clinical efﬁcacy

between laparoscopic and open surgery.25e28 They all showed that
laparoscopic surgery is superior in terms of blood loss, frequency of
postoperative complications, and length of hospital stay withoutcompromising the curative resection rate for cancer. It would bechallenging to show data surpassing such a high level of laparoscopic surgery.
In nearly every instance, it has been observed that RDG requires
a longer operative time, despite any minor deviations that may
exist (Fig. 5). Increased exposure to insufﬂation and the associatedincrease in anesthesia time are major concerns but are rarely
published. However, previous studies of LDG in the elderly haveshown that increased operative time has no detrimental effect withrespect to surgical outcomes.29 Therefore, increased operative timeshould not have such a direct impact on the patient's vital system.
One of the problems with operative time in the robotic surgery
group is docking time. Although docking time is an essential factor
that increases operative time, with the use of new robotic surgicalsystems, the new robotic surgical systems are expected to shorten
the time. Our study also showed that operative time had shortened
as a surgeon experienced more (Fig. 7). Multiple studies have reported that the da Vinci Xi robotic platform is easier to use andinstall in rectal and renal patients.30,31
Needless to say, lymph node dissection is important in gastriccancer surgery. It is because lymph node dissection and pathological examination to determine the site and number of metastases
can be used to estimate the stage of the disease and prevent
recurrence.32 Dissection of lymph nodes 8 and 11 is considered a
difﬁcult operation in laparoscopic surgery.33e35 In laparoscopic
surgery, forceps are mostly limited to a linear structure, and interms of mobility, they can only rotate about an axis or move in apinching motion. It makes it difﬁcult to strip lymphatics while
avoiding important blood vessels, or to make a patricidal approachto organs that should be avoided, such as the pancreas. Robotic
surgery facilitates the use of articulated forceps to approach lymph
nodes that may be located deeper within the narrow surgical ﬁeld.
The lymphatic dissection around the common hepatic artery andsplenic artery, which is particularly problematic, is less stressful
with robotic surgery compared to laparoscopic surgery.36 Our study
also suggested that more lymph nodes can be dissected by robotic
surgery than by laparoscopic surgery and that more precise andFig. 7. Comparison of operative time between RDG performed in 2016e2018 and2019e2020 before and after PSM.
6

M. Kitazono, M. Fujita, S. Uchiyama et al.

Asian Journal of Surgery xxx (xxxx) xxx

Table 6
Summary of short-term clinical outcomes before and after matching (RDG 2016e2018 vs. RDG 2019e2020).
Before PSM

After PSM

RDG 2016e2018 (n ¼ 32) RDG 2019e2020 (n ¼ 39) p-value RDG 2016e2018 (n ¼ 21) RDG 2019e2020 (n ¼ 21) p-value
Time to ﬁrst oral feeding(day)Mean ± SEM
3.8 ± 0.3
Median(IQR)
3.0 (3.0e4.0)
Surgery-related complications
Postoperative ileus
1 (3.1%)
Postoperative bleeding
0 (0.0%)
Postoperative bleeding anastomotic ulcer 1 (3.1%)
Postoperative wound infection
0 (0.0%)
Postoperative intra-abdominal abscess
1 (3.1%)
Reoperations
none
Mortality
none
Postoperative length of stay(day)Mean ± SEM
12.5 ± 0.6
Median(IQR)
12.0 (10.0e15.0)

3.5 ± 0.1
3.0 (3.0e4.0)

0.50836 3.9 ± 0.4
3.0 (3.0e4.0)

3.6 ± 0.2
3.0 (3.0e4.0)

0.988610 (0.0%)1 (2.6%)0 (0.0%)2 (5.1%)2 (5.1%)none
none

0.40506 1 (4.8%)
0 (0.0%)1 (4.8%)0 (0.0%)1 (4.8%)
e
none
e
none

0 (0.0%)1 (4.8%)0 (0.0%)2 (9.5%)0 (0.0%)none
none

0.3062213.4 ± 1.2
12.0 (10.0e13.0)

0.8521

12.4 ± 0.7
12.0 (10.0e13.3)

0.89546

12.5 ± 0.8
11.0 (9.8e16.3)ee

PSM¼Propensity score matching; LDG ¼ laparoscopic distal gastrectomy; RDG ¼ robot-assisted distal gastrectomy.
*P < 0.05 indicates statistical signiﬁcance (**P < 0.01, and ***P < 0.001).

involved in this work.

safer dissection is possible (Fig. 6).
5. Conclusions

References

Due to the high level of laparoscopic surgery, it is difﬁcult todetermine the superiority of robotic surgery over laparoscopic
surgery other than the number of lymph nodes dissection harvested. The other advantages are probably more signiﬁcant for thesurgeon than the patient. It is imagined that it reduces surgeon
fatigue and keeps them focused for extended periods of operative
time that can be shortened as a surgeon experiences more. As aresult, this would lead to more accurate and safer surgeries, fewer
complications, fewer hospital days, less risk of recurrence, and lessburden on the patient and society.
Technology, including electronics, will evolve further, and robotic surgery will sharpen its precision and safety even more.
Although cost-effectiveness may be an issue with robotic surgery
compared to laparoscopic surgery, the improved accuracy andsafety of the procedure may reduce complications and approximate
costs through the use of fewer drugs and shorter hospital stays.

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Authors’ contributions
MK designed the study and drafted the manuscript. MF analyzed
the data and edited the draft. SU, ME and NI participated in thecritical revision of the manuscript. All authors read and approved
the ﬁnal manuscript.
Funding
None.
Ethical approval
Informed consent was obtained from the patient regarding thereport of their clinical scenario data in an anonymous way.
Declaration of competing interest
The authors declare no conﬂicts of interest.
Acknowledgements
The authors would like to gratefully thank everyone who was7

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