Methods and compositions are provided for diagnosing 
lung cancer in a mammalian subject by use of three or more selected genes, e.g., a 
gene expression profile, from the 
peripheral blood mononuclear cells (PBMC) of the subject which is characteristic of 
disease, a stage of the 
disease, or enables prognosis of recurrence of 
disease. The 
gene expression profile includes three or more genes of Table I, Table II, Table III, Table IV, Table V, Table VI or Table VII herein. Detection of changes in expression in the selected genes forming the 
gene expression profile from that of a 
reference gene expression profile are correlated with non-
small cell lung cancer (NSCLC). One composition for use in such diagnosis includes three or more PCR primer-probe sets, wherein each primer-probe set amplifies a different 
polynucleotide sequence from the 
gene expression profile. Another composition for similar use contains a plurality of polynucleotides immobilized on a substrate, which probes hybridize to three or more 
gene expression products from genes in the 
gene expression profile. Still another composition involves detection of the 
protein expression products of genes from the gene expression profile.