Prognostic factors of minimally invasive surgery for gastric cancer: Does robotic gastrectomy bring oncological benefit?

Table 1 Clinicopathological characteristics of the entire cohort

Variables	n = 814
Age, yr [IQR]	68[61-74]
Sex, n (%)
Male	562 (69.0)
Female	252 (31.0)
BMI, kg/m2 [IQR]	22.2 [20.0-24.1]
ASA, n (%)
1	314 (38.6)
2	396 (48.6)
3	104 (12.8)
Clinical stage, n (%)
I	558 (68.6)
II	125 (15.3)
III	121 (14.9)
IV	10 (1.2)
Neoadjuvant chemotherapy, n (%)	119 (14.6)
Neoadjuvant radiotherapy, n (%)	0 (0)
Approach, n (%)
Laparoscopic	657 (80.7)
Robotic	157 (19.3)
Type of gastrectomy, n (%)
Distal	559 (68.7)
Total	238 (29.2)
Proximal	16 (2.0)
Pylorus preserving	1 (0.1)
Lymphadenectomy, n (%)
D1+	378 (46.4)
D2	436 (53.6)
Dissected nodes, n [IQR]	38[28-48]
Tumor size, mm [IQR]	30[20-50]
pT, n (%)
1	469 (57.6)
2	87 (10.7)
3	112 (13.8)
4	138 (17.0)
CR	8 (1.0)
pN, n (%)
0	559 (68.7)
1	98 (12.0)
2	79 (9.7)
3	78 (9.6)
pStage, n (%)
I	498 (61.2)
II	160 (19.7)
III	148 (18.2)
TCRNany	8 (1.0)
WHO histologic type, n (%)
Tub/pap	402 (49.4)
Por/sig	352 (43.2)
Mixed/other	60 (7.4)
Lymphovascular invasion, n (%)	531 (65.2)
Adjuvant chemotherapy, n (%)	242 (29.7)
Adjuvant radiotherapy, n (%)	0 (0)
Morbidity (C–D grade ≥ III), n (%)	72 (8.8)
Anastomotic leakage	22 (2.7)
Pancreatic fistula	30 (3.7)

Categorical and continuous data are presented as n (%) and median [IQR], respectively. IQR: Interquartile range; ASA: American Society of Anesthesiologists; BMI: Body mass index; CR: Complete response at the primary site; C-D: Clavien-Dindo classification.

Table 2 Factors associated with overall survival for the entire cohort (n = 814)

	Univariate			Multivariate
	HR	95%CI	P	HR	95%CI	P
Age > 65 yr	1.46	1.04–2.06	0.031	1.62	1.09–2.40	0.017
Female sex	0.75	0.52–1.09	0.129
BMI > 23 kg/m2	0.77	0.55–1.07	0.123
ASA
1	1			1
2	0.96	0.68–1.38	0.837	1.06	0.72–1.57	0.753
3	1.97	1.27–3.05	0.003	1.91	1.18–3.10	0.009
Neoadjuvant chemotherapy	1.84	1.27–2.67	0.001	1.34	0.88–2.04	0.166
Robotic approach	0.77	0.50–1.21	0.258
Type of gastrectomy
Distal/pylorus-preserving	1			1
Total/proximal	2.17	1.58–2.99	< 0.001	1.45	1.03–2.05	0.036
D2 lymphadenectomy	1.86	1.32–2.61	< 0.001	0.87	0.57–1.33	0.528
Tumor > 30 mm	3.23	2.20–4.75	< 0.001	1.05	0.66–1.69	0.832
WHO histologic type
Tub/pap	1			1
Por/sig/mixed/other	1.54	1.12–2.13	0.009	1.26	0.89–1.78	0.190
Lymphovascular invasion	4.38	2.68–7.17	< 0.001	1.17	0.60–2.26	0.651
pT
1	1			1
2	2.82	1.62–4.91	< 0.001	1.72	0.90–3.27	0.099
3	3.03	1.82–5.03	< 0.001	1.54	0.82–2.91	0.184
4	9.78	6.54–14.60	< 0.001	4.31	2.37–7.82	< 0.001
CR	1.67	0.23–12.17	0.613	1.34	0.16–10.97	0.784
pN
0	1			1
1	2.76	1.74–4.39	< 0.001	2.02	1.22–3.34	0.007
2	4.05	2.56–6.41	< 0.001	1.97	1.15–3.36	0.013
3	8.08	5.40–12.10	< 0.001	2.92	1.79–4.78	< 0.001
Adjuvant chemotherapy	3.27	2.37–4.50	< 0.001	1.21	0.80–1.82	0.371
Morbidity (C-D grade ≥ III)	1.85	1.18–2.91	0.008	1.27	0.79–2.05	0.325

HR: Hazard ratio; CI: Confidence interval; ASA: American Society of Anesthesiologists; BMI: Body mass index; CR: Complete response at the primary site; C-D: Clavien–Dindo classification.

Table 3 Factors associated with recurrence-free survival for the entire cohort (n = 814)

			Univariate		Multivariate
	HR		95%CI	P	HR	95%CI	P
Age > 65 yr	1.33		0.97–1.84	0.076	1.48	1.02–2.14	0.038
Female sex	0.76		0.54–1.06	0.108
BMI > 23 kg/m2	0.77		0.56–1.05	0.100
ASA
1	1				1
2	0.95		0.68–1.32	0.761	1.08	0.75–1.55	0.692
3	1.67		1.09–2.55	0.018	1.62	1.02–2.60	0.043
Neoadjuvant chemotherapy	1.91		1.34–2.71	< 0.001	1.39	0.93–2.08	0.104
Robotic approach	0.69		0.45–1.06	0.087	0.68	0.44–1.06	0.088
Type of gastrectomy
Distal/pylorus-preserving	1				1
Total/proximal	2.24		1.66–3.02	< 0.001	1.55	1.12–2.15	0.009
D2 lymphadenectomy	2.08		1.50–2.86	< 0.001	0.99	0.66–1.48	0.957
Tumor > 30 mm	3.19		2.23–4.56	< 0.001	0.95	0.61–1.48	0.827
WHO histologic type
Tub/pap	1				1
Por/sig/mixed/other	0.54		0.14–2.08	0.005	1.20	0.86–1.66	0.284
Lymphovascular invasion		4.93	3.06–7.94	< 0.001	1.29	0.69–2.43	0.430
pT
1	1				1
2	2.87		1.69–4.85	< 0.001	1.57	0.85–2.89	0.148
3	3.42		2.13–5.48	< 0.001	1.60	0.89–2.89	0.120
4	10.62		7.26–15.53	< 0.001	4.20	2.38–7.41	< 0.001
CR	1.41		0.19–10.24	0.737	0.96	0.12–7.77	0.967
pN
0	1				1
1	3.08		1.99–4.77	< 0.001	2.23	1.39–3.58	0.001
2	5.01		3.29–7.62	< 0.001	2.24	1.36–3.70	0.002
3	8.92		6.07–13.11	< 0.001	3.32	2.06–5.34	< 0.001
Adjuvant chemotherapy	3.53		2.62–4.77	< 0.001	1.18	0.80–1.73	0.410
Morbidity (C-D grade ≥ III)	1.69		1.09–2.62	0.019	1.04	0.65–1.67	0.868

ASA: American Society of Anesthesiologists; BMI: Body mass index; CR: Complete response at the primary site; C-D: Clavien–Dindo classification; HR: Hazard ratio; CI: Confidence interval.

Table 4 Factors associated with recurrence-free survival for patients with pathological stage II/III disease (n = 308)

	Univariate			Multivariate
	HR	95%CI	P	HR	95%CI	P
Age > 65 yr	1.04	0.73–1.48	0.848
Female sex	1.08	0.75–1.58	0.673
BMI > 23 kg/m2	0.69	0.47–1.00	0.052	0.92	0.62–1.35	0.657
ASA
1	1
2	0.82	0.56–1.19	0.297
3	1.07	0.63–1.80	0.809
Neoadjuvant chemotherapy	1.37	0.93–2.01	0.114
Robotic approach	0.50	0.30–0.83	0.007	0.56	0.33–0.96	0.035
Type of gastrectomy
Distal/pylorus-preserving	1			1
Total/proximal	1.67	1.18–2.37	0.004	1.32	0.91–1.90	0.145
D2 lymphadenectomy	1.26	0.80–2.00	0.320
Tumor > 30 mm	2.17	1.17–4.03	0.014	1.34	0.69–2.60	0.303
WHO histologic type
Tub/pap	1			1
Por/sig/mixed/other	1.38	0.95–2.00	0.089	1.29	0.88–1.90	0.197
pT
1	1			1
2	1.82	0.60–5.53	0.292	1.33	0.42–4.23	0.628
3	1.32	0.47–3.75	0.6	1.45	0.49–4.30	0.505
4	3.96	1.45–10.83	0.007	3.52	1.23–10.07	0.019
pN
0	1			1
1	2.07	1.16–3.69	0.014	2.86	1.57–5.24	0.001
2	2.24	1.29–3.90	0.004	2.45	1.38–4.34	0.002
3	3.74	2.21–6.32	< 0.001	3.25	1.88–5.61	< 0.001
Adjuvant chemotherapy	1.37	0.92–2.04	0.119
Morbidity (C-D grade ≥ III)	1.58	0.97–2.58	0.066	1.22	0.73–2.05	0.453

ASA: American Society of Anesthesiologists; BMI: Body mass index; C–D: Clavien–Dindo classification; HR: Hazard ratio; CI: Confidence interval.

Table 5 Clinicopathological characteristics of pStage II/III patients in the pre- and postmatched cohort

	Prematched				Postmatched
	Lap (n = 241)	Robotic (n = 67)	P	ASD	Lap (n = 61)	Robotic (n = 61)	P	ASD
Sex, n (%)			0.132	0.204			0.580	0.100
Male	174 (72.2)	42 (62.7)			35 (57.4)	38 (62.3)
Female	67 (27.8)	25 (37.3)			26 (42.6)	23 (37.7)
Age, yr [IQR]	69 [61–75]	65 [60–77]	0.134	0.235	68 [61–75]	65 [60–77]	0.824	0.042
BMI, kg/m2 [IQR]	21.6 [19.2–23.7]	23.1 [20.0–24.8]	0.008	0.329	22.6 [20.4–24.9]	23.0 [20.0–24.9]	0.810	0.007
ASA, n (%)			0.074	0.315			0.959	0.052
1	89 (36.9)	35 (52.2)			31 (50.8)	30 (49.2)
2	118 (49.0)	24 (35.8)			23 (37.7)	23 (37.7)
3	34 (14.1)	8 (11.9)			7 (11.5)	8 (13.1)
Neoadjuvant chemotherapy, n (%)	61 (25.3)	11 (16.4)	0.128	0.220	10 (16.4)	11 (18.0)	0.810	0.043
Type of gastrectomy, n (%)			0.075	0.329			1	< 0.001
Distal	136 (56.4)	48 (71.6)			42 (68.9)	42 (68.9)
Total	104 (43.2)	19 (28.4)			19 (31.1)	19 (31.1)
Proximal	1 (0.4)	0 (0)			0 (0)	0 (0)
Tumor size, mm [IQR]	50[35-70]	40[30-63]	0.026	0.265	50 [35–77]	43 [30–65]	0.192	0.187
pT, n (%)			0.042	0.391			0.860	0.158
1	11 (4.6)	8 (11.9)			4 (6.6)	6 (9.8)
2	35 (14.5)	4 (6.0)			4 (6.6)	4 (6.6)
3	85 (35.3)	27 (40.3)			21 (34.4)	23 (37.7)
4	110 (45.6)	28 (41.8)			32 (52.5)	28 (45.9)
pN, n (%)			0.15	0.338			0.617	0.244
0	65 (27.0)	24 (35.8)			16 (26.2)	22 (36.1)
1	48 (19.9)	15 (22.4)			17 (27.9)	13 (21.3)
2	68 (28.2)	10 (14.9)			9 (14.8)	10 (16.4)
3	60 (24.9)	18 (26.9)			19 (31.1)	16 (26.2)
pStage, n (%)			0.246				0.716
II	121 (50.2)	39 (58.2)			32 (52.5)	34 (55.7)
III	120 (49.8)	28 (41.8)			29 (47.5)	27 (44.3)
Dissected nodes, n [IQR]	44 [35–53]	43 [35–51]	0.858		45 [35–54]	43 [30-65]	0.556
WHO histological type, n (%)			0.667				0.229
Tub/pap	88 (36.5)	27 (41.8)			17 (27.9)	26 (42.6)
Por/sig	129 (53.5)	34 (50.7)			37 (60.7)	30 (49.2)
Mixed/other	24 (10.0)	5 (7.5)			7 (11.5)	5 (8.2)
Lymphovascular invasion, n (%)	241 (100)	66 (98.5)	0.218		61 (100)	60 (98.4)	0.5
Adjuvant chemotherapy, n (%)	161 (66.8)	47 (70.1)	0.605		38 (62.3)	43 (70.5)	0.338
Morbidity (C-D grade ≥ III), n (%)	31 (12.9)	3 (4.5)	0.053		10 (16.4)	3 (4.9)	0.04

Categorical and continuous data are presented as n (%) and median [IQR], respectively. ASA: American Society of Anesthesiologists; BMI: Body mass index; CR: Complete response at the primary site; C–D: Clavien–Dindo classification; ASD: Absolute standardized mean difference.