Table 3. Comparison of the c-indices of different survival prediction models (n = 51).

Model	c-index for OS	p valuea	c-index for PFS	p valuea
Our prediction model	0.691	NA	0.649	NA
TNM staging systemb	0.574	0.013	0.517	0.004
Mutation type of EGFRc	0.549	0.003	0.515	0.001
Treatment responsed	0.625	0.184	0.598	0.210

OS: Overall survival, PFS: Progression-free survival, NA: Not applicable.

^aCompared to our prediction model.

^bStaging was based on the 7^th American Joint Committee on Cancer system.

^cStratified according to the presence or absence of the exon 19 deletion.

^dResponse assessment was based on RECIST 1.1 criteria.