Primed In Situ Labelling for Determination of HER-2 and CEN-17 Status in Breast Cancer

ERBB2/HER-2 (HER-2/neu, NEU, NGL, HER-2, TKR1, CD340) is a 185 kDa transmembrane growth factor receptor and one of the four members of type 1 growth factor receptor family, designated HER1 to HER4 (c-erbB-1 to c-erbB-4). It has been shown to play a role in the signal transduction of cell growth but has no known natural ligand and instead seems to be activated via dimerisation with other receptors in the family: EGFR, HER3 or HER4 (Yarden and Sliwkowski, 2001). HER2 oncogene is located on the long arm of chromosome 17 (17q12-q21) (Owens et al., 2004) and plays a role in the pathogenesis of a significant number of human tumours. Approximately 20–30% of breast carcinomas and probably a higher percentage in the more malignant subgroups that form lymph node or distant metastases show altered HER-2 expression (Eccles, 2002; Carlsson et al., 2004). This is manifested as gene amplification and/or protein overexpression (Ross and Fletcher, 1999). It has been shown in many studies that overexpression of the HER-2 protein correlates with amplification of the HER-2 gene (Tubbs et al., 2000). These alterations are associated with shorter disease free period and overall