Except for PECAM1, which showed a significant decrease (P < 0.05), while the TCGA dataset revealed no significant difference, the expression levels (up or down) of the rest 14 selected genes were consistent with TCGA profiles as validated by real time RT-PCR assay for all recruited patients and a clustering analysis was performed in the primary of HNSCC (Figure 2). Here, PECAM1 is linked to head and neck squamous cell carcinoma.