Table 2 Cox proportional-hazards model evaluating the effect of the clinical variables on progression-free survival

Age (every one year)

1.00

0.99–1.01

0.552

1.00

0.99–1.01

0.904

Sex (male vs. female)

1.42

1.13–1.77

0.003^*

1.21

0.96–1.54

0.108

ECOG PS

 0

Ref

Ref

 1

1.82

1.39–2.39

 < 0.001^*

1.58

1.18–2.11

0.002^*

  ≥ 2

2.76

1.99–3.82

 < 0.001^*

2.36

1.65–3.36

 < 0.001^*

Group

 TC-/PPI-

Ref

Ref

 TC + /PPI-

0.70

0.49–0.99

0.044^*

1.10

0.75–1.61

0.615

 TC-/PPI + 

1.43

1.11–1.86

0.006^*

1.29

0.99–1.68

0.062

 TC + /PPI + 

1.05

0.75–1.48

0.776

1.37

0.95–1.98

0.097

Brain metastases

2.01

1.59–2.56

 < 0.001^*

1.60

1.25–2.04

 < 0.001^*

Skin rash

0.32

0.25–0.41

 < 0.001^*

0.35

0.26–0.47

 < 0.001^*