Discordance between EGFR expression and clinicopathologic parameters of colorectal adenocarcinoma in Taiwan

Dysregulation of epidermal growth factor receptor (EGFR) has been associated with colorectal cancer, but no evidence shows a relationship of EGFR expression to clinicopathological parameters in colorectal cancer in Taiwan. Immunohistochemical analysis of EGFR, Ki67, and p53 was performed in tissue microarray slides of 9 normal glandular tissues and 150 specimens including 49 well, 58 moderately, and 43 poorly differentiated colorectal adenocarcinomas. Differences in intensity of EGFR immunostaining and the percentages of Ki67 and p53 positive cells between normal and tumor specimens were evaluated using the Student t-test, one-way ANOVA, and linear regression analysis. Intensity of EGFR staining was weak and nuclear expression of Ki67 and p53 was scattered in all 9 control specimens. Expression of Ki67 and p53 but not EGFR was significantly higher in more advanced grades and TNM stages of colorectal adenocarcinoma than in normal controls. The percentages of Ki67 and p53 stained tumor cells were significantly higher in moderately (Ki67: 60.3 ± 6.5, p53: 47.6 ± 3.8) and poorly (Ki67: 61.8 ± 5.3, p53: 55.1 ± 4.1) differentiated tumor cells than in well differentiated (Ki67: 40.8 ± 4.4, p53: 39.8 ± 4.2) tumor cells. Additionally, the Ki67 and p53 staining intensity was also significantly correlated with the more advanced T, N and American Joint Committee on Cancer (AJCC) clinical stage of colorectal adenocarcinoma, suggesting their usefulness as biomarkers of colorectal adenocarcinoma progression. In conclusion, EGFR immunochemistry may not be a good method for pre-treatment evaluation of colorectal adenocarcinoma in Taiwan.