Table 1 Patient demographics and baseline characteristics

Age, years

Mean ± SD

43 ± 10

27 ± 2

42 ± 7

59 ± 4

-

-

Range

18, 76

18, 30

31, 54

55, 76

Male sex

325 (24.0%)

53 (30.6%)

231 (23.6%)

41 (20.6%)

5.53

0.063²

Tumor size, cm

Mean ± SD

0.61 ± 0.20

0.62 ± 0.21

0.60 ± 0.20

0.62 ± 0.21

1.10

0.332³

Range

0.1, 1.0

0.1, 1.0

0.1, 1.0

0.1, 1.0

Tumor location

upper

282 (20.9%)

28 (16.2%)

209 (21.3%)

45 (22.6%)

5.73

0.454²

middle

614 (45.4%)

84 (48.6%)

441 (45.0%)

89 (44.7%)

lower

289 (21.4%)

40 (23.1%)

214 (21.8%)

35 (17.6%)

multifocal

167 (12.4%)

21 (12.1%)

116 (11.8%)

30 (15.1%)

Aggressive variant

12 (0.9%)

1 (0.6%)

8 (0.8%)

3 (1.5%)

-

0.629⁴

HT

338 (25.0%)

47 (27.2%)

235 (24.0%)

56 (28.1%)

2.02

0.363²

LVI

5 (0.4%)

2 (1.2%)

2 (0.2%)

1 (0.5%)

-

0.088⁴

mETE

467 (34.5%)

51 (29.5%)

336 (34.3%)

80 (40.2%)

4.81

0.090²

pN1a stage

487 (36.0%)

95 (54.9%)

350 (35.7%)

42 (21.1%)

46.04

< 0.001²

N of mLNs

Mean ± SD

0.82 ± 1.45

1.43 ± 1.81

0.79 ± 1.41

0.43 ± 1.08

23.40

< 0.001³

Range

0, 11

0, 8

0, 11

0, 7

N of mLNs ≥ 5

50 (3.7%)

14 (8.1%)

31 (3.2%)

5 (2.5%)

10.95

0.004²

LNR, Mean ± SD

0.14 ± 0.25

0.24 ± 0.30

0.14 ± 0.24

0.07 ± 0.19

21.20

< 0.001³

ENE

43 (3.2%)

9 (5.2%)

31 (3.2%)

3 (1.5%)

4.11

0.128²

High-risk LNM

85 (6.3%)

21 (12.1%)

56 (5.7%)

8 (4.0%)

12.34

0.002²

TNM stage

I

1,310 (96.9%)

173 (100.0%)

980 (100.0%)

157 (78.9%)

251.15

< 0.001²

II

42 (3.1%)

0 (0.0%)

0 (0.0%)

42 (21.1%)

ATA risk group

low

856 (63.3%)

115 (66.5%)

624 (63.7%)

117 (58.8%)

2.55

0.280²

intermediate

496 (36.7%)

58 (33.5%)

356 (36.3%)

82 (41.2%)