Table 2 Correlation between PD-L1 expression, NLNs and clinicopathological characteristics in training cohort

Sex

0.819*

0.773*

 Male

47 (72.3)

43 (74.1)

49 (74.2)

41 (71.9)

 Female

18 (27.7)

15 (25.9)

17 (25.8)

16 (28.1)

Age (years, mean ± SD)

59.5 ± 8.9

59.5 ± 9.1

0.980**

60.0 ± 7.9

59.0 ± 10.0

0.544**

Smoking status

0.832*

0.424*

 No

27 (41.5)

23 (39.7)

29 (43.9)

21 (36.8)

 Yes

38 (58.5)

35 (60.3)

37 (56.1)

36 (63.2)

Drinking status

0.549*

0.625*

 No

48 (73.8)

40 (69.0)

46 (69.7)

42 (73.7)

 Yes

17 (26.2)

18 (31.0)

20 (30.3)

15 (26.3)

Tumor length (cm, mean ± SD)

3.8 ± 1.6

3.6 ± 1.7

0.440**

3.6 ± 1.5

3.8 ± 1.8

0.584**

Surgical approach

0.525*

0.002*

 Left thorax

46 (70.8)

44 (75.9)

56 (84.8)

34 (59.6)

 Right thorax

19 (29.2)

14 (24.1)

10 (15.2)

23 (40.4)

NLNs

0.077*

–

 ≤ 16

30 (46.2)

36 (62.1)

–

–

 > 16

35 (53.8)

22 (37.9)

–

–

Differentiation

0.701*

0.385*

 Well-moderate

28 (43.1)

23 (29.7)

25 (37.9)

26 (45.6)

 Poor

37 (56.9)

35 (60.3)

41 (62.1)

31 (54.4)

pT stage

0.796*

0.215*

 T2

25 (38.5)

21 (36.2)

28 (42.4)

18 (31.6)

 T3

40 (61.5)

37 (63.8)

38 (57.6)

39 (68.4)

pTNM stage

0.254*

0.811*

 IB

23 (35.4)

15 (25.9)

21 (31.8)

17 (29.8)

 IIA

42 (64.6)

43 (74.1)

45 (68.2)

40 (70.2)

PD-L1 expression

–

0.077*

 Low

–

–

30 (45.5)

35 (61.4)

 High

–

–

36 (54.5)

22 (38.6)

LNs dissection of left recurrent laryngeal nerve

0.813*

0.454*

 No

20 (30.8)

19 (32.8)

19 (28.8)

20 (35.1)

 Yes

45 (69.2)

39 (67.2)

47 (71.2)

37 (64.9)

LNs dissection of right recurrent laryngeal nerve

0.416*

0.586*

 No

18 (27.7)

20 (34.5)

19 (28.8)

19 (33.3)

 Yes

47 (72.3)

38 (65.5)

47 (71.2)

38 (66.7)

Dissection of left gastric artery LNs

0.706***

0.121***

 No

3 (4.6)

4 (6.9)

6 (9.1)

1 (1.8)

 Yes

62 (95.4)

54 (93.1)

66 (90.9)

56 (98.2)

Dissection of subcarinal LNs

0.498***

0.732***

 No

6 (9.2)

3 (5.2)

4 (6.1)

5 (8.8)

 Yes

59 (90.8)

55 (94.8)

62 (93.9)

52 (91.2)