HER 2 status in invasive breast cancer: Immunohistochemistry, fluorescence in-situ hybridization and chromogenic in-situ hybridization.

Introduction : HER2/neu gene status in breast cancers can be evaluated by targeting protein and gene - immunohistochemistry (IHC) and fluorescence in-situ hybridization (FISH). Recent studies have shown chromogenic in-situ hybridization (CISH) as a relatively cheaper alternative. Materials and Methods : Forty-three nonconsecutive, randomly selected primary invasive breast cancer cases were evaluated for c-erbB-2 (HER2 protein) by IHC and gene amplification by FISH and CISH. Results of each of the same were compared. Results : CISH showed approximately 90% and 100% concordance for IHC negative and positive cases, respectively; while approximately 94.4% and 91% concordance with FISH amplified and non-amplified cases, respectively. Conclusion : This study showed feasibility of incorporation of CISH as a low cost option in routine management of breast carcinoma in the Indian setting. Secondly, reconfirmation of IHC negative and positive cases can be done by CISH.