Table 1. Clinical and pathological characteristics of included patients.

Variables	n (%)
BMI, body mass index; ECOG, Eastern Cooperative Oncology Group; LMLND, lower mediastinal lymph node dissection; TH, transhiatal. *, Because of the technical errors of the surgical videos, three patients didnot have the data of the dissection time of the LMLND, and one patient didnot have the data of pleural injuries under TH approach. #, Patients combined with trans-thoracic surgeries were excluded.
Sex
Male	33 (94.3)
Female	2 (5.7)
Age (year) ()	64.7±5.9
BMI (kg/m2) ()	23.7±2.6
ECOG score
0	29 (82.9)
1	5 (14.3)
3	1 (2.9)
Preoperative treatment	19 (54.3)
(y)cT
(y)cT2	4 (11.4)
(y)cT3	21 (60.0)
(y)cT4a	10 (28.6)
(y)cN
(y)cN0	4 (11.4)
(y)cN1	12 (34.3)
(y)cN2	19 (54.3)
Surgical approach
Laparoscopic-assisted	31 (88.6)
Total laparoscopic	4 (11.4)
Extension of gastrectomy
Total gastrectomy	27 (77.1)
Proximal gastrectomy	8 (22.9)
Extension of lymph node dissection
D1+	2 (5.7)
D2	33 (94.3)
Extension of LMLND
Stations 110 and 111	7 (20.0)
Stations 110, 111, and part of 112	28 (80.0)
Combined organ resection	2 (5.7)
Combined trans-thoracic surgery	3 (8.6)
Transfer to open surgery	1 (2.9)
Pleural injury under TH approach*
No injuries	21 (61.8)
Injuries to both sides	2 (5.9)
Injuries to left side	9 (26.5)
Injuries to right side	2 (5.9)
Operation time (min) ()#	309.8±69.5
Dissection time of LMLND (min) ()*	18.2±6.3
Incision length (cm) ()#	9.5±4.0
Intra-operative blood loss (mL) ()#	100±70.4
Intra-operative blood transfusion	0 (0)
Siewert type
Type I	1 (2.9)
Type II	26 (74.3)
Type III	8 (22.9)
Esophageal resection (cm)#	2.5±1.0
Tumor length (cm)	4.7±2.8
Proximal margin (cm)#	1.7±0.7
Esophageal invasion (cm)	1.1±1.0
Bormann type
Type 1	2 (5.7)
Type 2	7 (20.0)
Type 3	24 (68.6)
Type 4	2 (5.7)
No. of LMLND ()	2.0±2.8
Lower mediastinal metastasis	4 (11.4)