Immunohistochemical detection of receptor tyrosine kinases c-kit, EGF-R, and PDGF-R in colorectal adenocarcinomas

The selective inhibition of tyrosine kinases is a promising strategy in the treatment of several human malignancies. This study aimed to clarify expression patterns of therapeutically addressable receptor tyrosine kinases in colorectal cancer. In this study, we used tissue arrays to analyze 263 specimen of colorectal carcinoma for the expression of the tyrosine kinases c-kit (CD117), epidermal growth factor receptor (EGF-R), and platelet-derived growth factor receptor (PDGF-R). Staining patterns were then correlated with tumor stage and survival. Five tumors (1.9%) showed a strong expression of c-kit (CD117), while in 40 samples (15.2%), a weak/intermediate expression was observed. Positive staining did not correlate with histopathological parameters although a trend toward a better survival of c-kit-positive patients was observed. No positivity for PDGF-R was observed in 263 samples of colorectal carcinomas. Positive EGF-R expression was identified in 39 cases (15.2%), whereas 218 samples (84.8%) stained negative. Our study confirms that expression of the tyrosine kinases c-kit and PDGF-R are rare in colorectal carcinomas and do not correlate with tumor stage.