Epidermal growth factor receptor (EGFR) gene copy number in colorectal adenoma-carcinoma progression

Adenomas are the easily identifiable precursors of the vast majority of colorectal cancers. Some of their morphological features, such as dysplasia, are predictive of their biological evolution toward adenocarcinomas. A large body of evidence has demonstrated that the epidermal growth factor receptor (EGFR) signaling pathway is commonly activated in colorectal cancer and EGFR-target therapies have improved the outcome for colorectal cancer patients. Nevertheless, the mechanisms underlying the role of EGFR in the adenoma-carcinoma sequence are not entirely clear. We retrospectively analyzed EGFR gene copy number by fluorescence in situ hybridization (FISH) in paraffin-embedded tissue from 215 patients recruited through a prospective colorectal cancer screening procedure and undergoing surgical colectomy. We observed that in human colorectal carcinogenesis, EGFR copy number increases progressively, from adenomas with high-grade dysplasia to locally advanced adenocarcinomas, through early invasive adenocarcinomas, suggesting that deregulation of EGFR may correlate with the malignant progression.