Comparing fluorescence in situ hybridization and chromogenic in situ hybridization methods to determine the HER2/neu status in primary breast carcinoma using tissue microarray

Identification of HER2/neu status is important for predicting response to specific chemotherapy in breast carcinoma. Chromogenic in situ hybridization was performed using tissue microarray technology on 188 primary breast carcinomas. To validate the reliability of novel chromogenic in situ hybridization technology, the results of chromogenic in situ hybridization were correlated with the results of two-color fluorescence in situ hybridization done with the same tumors. On tissue microarray panels containing 188 breast carcinoma tissues, fluorescence in situ hybridization and chromogenic in situ hybridization were conducted simultaneously. HER2/neu amplification was detected in 46 tumors (24.5%) by fluorescence in situ hybridization and in 43 tumors (22.9%) by chromogenic in situ hybridization. Results of each method agreed with each other in 177 tumors (concordance: 94.1%). HER2/neu amplification by fluorescence in situ hybridization was associated with nuclear pleomorphism (P = .021), and HER2/neu amplification by chromogenic in situ hybridization was associated with poor nuclear grade (P = .037). High concordance between fluorescence in situ hybridization and chromogenic in situ hybridization indicated that chromogenic in situ hybridization can be a tempting alternative to fluorescence in situ hybridization for the detection of HER2/neu amplification in breast carcinoma because of its accuracy and relative low cost. HER2/neu appeared to have a prognostic implication because its amplification was associated with aggressive biologic features of the breast carcinoma. Integration of tissue microarray technology enabled high-throughput determination of HER2/neu amplification profile with rapidity and accuracy in large cohorts of the breast carcinoma.