Immunohistochemical scoring:
The primary mass EGFR expression results were compared to a negative control (benign vocal cord polyp). By combining the two scores mentioned above, an immunostaining score was created that ranged from 0 to 6. The immunostaining score was then used to categorize the immunohistological expression of EGFR: immunostaining scores of 0 indicate no expression, 1-2 indicate weak expression, 3-4 indicate moderate expression, and 5-6 indicate strong expression. Strong and moderate EGFR expression was considered positive in the results, but no or weak EGFR expression was regarded as negative.
The membranous expression of EGFR in tumor cells was observed. The intensity of the staining was determined using a semi-quantitative method, and the number of labeled cells with malignant features was determined in accordance with both the intensity and the proportion of stained cells. Scores were determined based on:
1- Expression of membranous EGFR
2- Intensity of staining
The intensity scale was determined using semi-quantative method in which 4 grades were obtained as follow: 0: no staining; 1: weak, 2: moderate; and 3: intense staining. The proportion of cells staining was also scored on a 4-point scale: 0: no cells staining; 1: less than one-third of cells staining; 2: between one-third and two-thirds of cells staining; 3: more than two-thirds of cells staining.