Table 2 Univariable and multivariable analyses of covariables associated with OS

Age ≥ 60 vs. <60

1.30 [0.93,1.81]

0.121

0.82 [0.56,1.22]

0.332

Female vs. Male

0.90 [0.64,1.26]

0.535

Smoking status Yes vs. Never

1.24 [0.86,1.77]

0.247

KPS ≤ 70 vs. ˃70

2.22 [1.41,3.52]

0.001

1.56 [0.96,2.53]

0.074

BMs at initial diagnosis

Metachronous vs. Synchronous

1.88 [1.31,2.71]

0.001

2.18 [1.44,3.30]

< 0.001

BM Numbers ˃4 vs. 1–4

1.60 [1.14,2.24]

0.007

1.35 [0.90,2.02]

0.147

Symptoms of BMs Yes vs. No

1.21 [0.86,1.68]

0.273

ECM Yes vs. No

1.94 [1.27,2.95]

0.002

1.01 [0.59,1.74]

0.974

EGFR mutation

L858R vs. 19 del

1.81[1.27,2.58]

0.001

1.81 [1.23,2.65]

0.002

Nonclassic vs. 19 del

2.82[1.50,5.31]

0.001

1.99 [1.01,3.91]

0.047

Treatment of EGFR-TKIs at BMs

3rd vs. 1/2rd EGFR-TKIs

0.89 [0.63,1.26]

0.504

Treatment Modality

Upfront WBRT vs. Upfront TKI

1.20[0.83,1.75]

0.337

1.25 [0.84,1.86]

Upfront SRS/fSRS vs. Upfront TKI

0.54[0.32,0.90]

0.018

0.61 [0.36,1.03]

0.066

DS-GPA 2.0–4.0 vs. 0-1.5

0.47 [0.33,0.66]

< 0.001

0.54 [0.33,0.90]

0.017