Table 1 Baseline characteristics of the enrolled patients

Overall

36

Age (years)

< 70

13

≥ 70

23

Mean ± SD

74.44 ± 8.46

Range

60–91

Gender

Male

21

Female

15

ECOG score

0

10

1

20

2

6

Histological types

Adenocarcinoma

27

Squamous cell carcinoma

9

T stage

T1a

12

T1b

15

T1c

5

T2a

4

Tumor size

0.5–1 cm

13

1.1–2 cm

15

2.1–3 cm

5

3.1–4 cm

3

Clinical stage

IA

32

IB

4

Ablative margin

< 5 mm

18

≥ 5 mm

18

Mean ± SD

0.51 ± 0.17

Range

2.8–8.8 mm