Table 4. The MTSBM in the patients without BM at the diagnosis of NSCLC.

Patient group	Event of SBM / patient no.	MTSBM (month)	P of log-rank test
All stages			0.043
WT (ref.)	18 / 162	NR
Mut	45 / 135	31.6
Stage IIIB-IV			0.017
WT (ref.)	14 / 132	NR
Mut	39 / 105	23.5
Stage IIIB-IV, with mutated-EGFRs			0.743
Exon 19	17 / 43	26.4
L858R (ref.)	20 / 58	22.9

MTSBM: median time interval between the diagnosis of lung cancer and the detection of subsequent brain metastases; BM: brain metastases; NSCLC: non-small cell lung cancer; SBM: subsequent BM; Patient no.: patient number; WT: wild-type; Mut: mutated; EGFR: epidermal growth factor receptor; NR: not reached. The MTSBM was estimated using the Kaplan- Meier method and group difference (i.e., EGFR mutations) was compared using log-rank tests.