Staining for EGFR in representative HNSCC samples. The EGFR score (0-16) in tumor samples was calculated as a product of staining intensity (1-4) multiplied by the percentage of positive cells (0-4). Tumor sample with low EGFR expression and EGFR score 2 (a). Tumor sample with high EGFR expression and EGFR score 12 (b). Homogenous expression of EGFR was found in the membranes and cytoplasm of tumor cells (Mag. × 100).