Evaluation of c-erbB-2 amplification in breast carcinoma by differential polymerase chain reaction

Previous studies have found that amplification and overexpression of the c-erbB-2 oncogene in mammary ductal adenocarcinomas predicts decreased disease-free or overall survival. Information regarding the prognostic and pathogenetic significance of oncogene amplification has been limited by difficulty obtaining sufficient quantities of high molecular weight DNA for Southern blot analysis. Differential polymerase chain reaction (PCR) has been suggested as an alternative method for evaluating gene amplification and can be performed using formalin-fixed paraffin-embedded specimens. The authors of this study used differential PCR to detect c-erbB-2 gene amplification and immunohistochemistry to evaluate c-erbB-2 expression. A highly significant degree of concordance (P < .002) between c-erbB-2 amplification and expression was observed. Abnormalities of c-erbB-2 copy number or expression were more common in tumors with higher histologic grade, and trends were noted toward association with other prognostically unfavorable biologic markers, such as reduced progesterone receptor content and DNA aneuploidy.