As shown in Table 1, of the four cytokines (proteins) which were detected in the plasma at the highest levels prior to stage I lung cancer resection (CCL3 (Chemokine with CC motif ligand 3), IL8 (Interleukin 8), IL6 (Interleukin 6), IL1β (Interleukin 1 beta)), three were corroborated by the PBMC gene expression data from the microarray database (CCL3, IL8, IL1β) at the mRNA level. Here, CCL3 is linked to lung cancer.