Immunohistochemical Expression of HER2/neu in Colorectal Carcinoma

Colorectal carcinoma ranks fourth among the most common leading causes of cancer-related mortality in the world. Her2/neu oncogen is one of four epidermal growth factor receptors. It's located on chromosome 17q21 and encodes a 185 transmembrane protein with tyrosine kinase activity that functions as a growth factor receptor. Clinically, amplification and/or overexpression of Her2/neu has been associated with poor prognosis in a number of tumor types such as breast and ovarian cancer. Conflicting data exist about the prevalence of HER-2/neu overexpression in colorectal cancer ranging from 0 to 83%. The aim of this study was to clarify the extent of HER-2/neu expression in colorectal cancers and its relationship to other clinicopathological parameters. This work involved 50 specimens of surgically resected colorectal cancers. HER2/neu immunohistochemistry was performed using the C-erbB-2 gene product. Out of 50 specimens, 13 were HER2/neu positive (26%), 6 (12%) were moderately and 7 (14%) were strongly positive. A significant relationship was found between membranous HER2 expression and tumor stage. Thus, it was concluded that colorectal carcinomas, especially those with advanced stage, should be subjected to HER2/neu expression studies, as the tumors which expressed HER2/neu could carry a poor prognosis and therefore would require a different therapeutic approach, as these cases could respond to Trastuzumab (Herceptin) therapy as well as other new treatment modalities.