DEG characterization. A. Hierarchical clustering of 1230 over-expressed and 136 under-expressed probes that correspond to 788 and 107 genes respectively classifying the 246 tissue samples into three clusters of healthy mucosa (green), tumors (red) and adjacent mucosa (blue). Highlighted in black, the group of 24 adjacent samples showing an extreme phenotype. B. Representative DEG patterns are displayed. DEG between adjacent and mucosa were classified as “Tumor-like”, “Trend” and “Adjacent-specific” genes. C. PCA using “Adjacent-specific” DEG. Tumor samples (T) are painted in red, adjacent samples (A) in blue and healthy mucosa (H) in green. The 24 adjacent samples showing an extreme phenotype are circled with a dot line.