Table 1 Patient characteristics

Age, years

0.949

Median (range)

61 (32–89)

60 (38–86)

61 (41–89)

 < 61

46

16

30

 ≥ 61

48

17

31

Gender

0.414

 Female

53

17

36

 Male

41

16

25

ECOG PS

0.986

 0–1

77

27

50

 ≥ 2

17

6

11

Tumor location

0.896

 Right lung

44

15

29

 Left lung

23

9

14

 Right + left

27

9

18

Tumor size at baseline (cm)

0.914

 ≤ 3 

17

6

11

 > 3–5

31

10

21

 > 5 

46

17

29

M-Staging

0.206

 M0

13

4

9

 M1a

20

4

16

 M1b

61

25

36

Brain metastasis at baseline

0.093

 No

67

20

47

 Yes

27

13

14

Bone metastasis at baseline

0.892

 No

55

19

36

 Yes

39

14

25

Liver metastasis at baseline

0.718

 No

75

27

48

 Yes

19

6

13

Pleural effusion at baseline

0.608

 No

63

21

42

 Yes

31

12

19

EGFR mutation type

0.791

 E19del

61

22

39

 L858R

33

11

22

EGFR plasma at baseline

–

 Negative

17

17

–

 Positive

16

16

–

Treatment method

0.750

 TKI alone

55

21

34

 TKI + Che/Ra

17

5

12

 TKI + Sur

22

7

15

Response

0.134

 PR + SD

28

13

15

 PD

66

20

46

Brain metastasis after treatment

0.986

 No

77

27

50

 Yes

17

6

11

Bone metastasis after treatment

0.207

 No

62

19

43

 Yes

32

14

18

Liver metastasis after treatment

0.277

 No

69

22

47

 Yes

25

11

14

Pleural effusion after treatment

0.131

 No

68

27

41

 Yes

26

6

20

New metastasis site

0.655

 No

57

19

38

 Yes

37

14

23

EGFR plasma after treatment

0.076

 Negative

37

17

20

 Positive

57

16

41

Secondary T790M mutation

0.308

 Negative

62

24

38

 Positive

32

9

23

Median cfDNA, ng/mL

183 (134–231)

175 (110–218)

199 (135–314)

0.276

 ≤ 200 

54

22

32

 > 200 

40

11

29

Survival

0.173

 Alive

39

16

23

 Dead

33

13

20

 Lost to follow-up

22

4

18