Tissue microarray analysis of EGFR gene amplification and gain in Bulgarian patients with colorectal cancer

Colorectal cancer is one of the most common neoplastic diseases and a leading cause of cancer-related deaths. Overexpression of epidermal growth factor receptor (EGFR) is commonly associated with this cancer. The aim of our study was to determine the frequency of epidermal growth factor receptor gene amplification and gain in a large number of colorectal carcinomas, arranged in a tissue microarray, in order to assess their role in colorectal cancer development. A tissue microarray of 498 patients with colorectal tumors was constructed, and 239 samples for EGFR copy number changes were successfully analyzed by fluorescence in situ hybridization. No amplification of EGFR was detected in our cohort of patients with colorectal tumors, and the EGFR gene was upregulated in only 2 tumors (0.84%). Therefore, the development of colon cancer in patients cannot be explained by copy number changes of the EGFR gene.