Comparison between immunohistochemistry and chromogenic in situ hybridization in assessing HER-2 status in breast cancer

Pathol Int. 2005 Jun;55(6):318-23. doi: 10.1111/j.1440-1827.2005.01831.x.


Human epidermal growth factor receptor-2 (HER-2) is usually determined as a potential target for breast cancer therapy. The purpose of the present study was to compare chromogenic in situ hybridization (CISH) with immunohistochemistry (IHC) in determination of HER-2 status, in metastatic breast cancer patients screened for the clinical study of chemotherapy +/- herceptin. It was possible to assess both CISH and IHC in 56 cases, using CISH Detection Kit (Zymed) and HercepTest (DakoCytomation), respectively. HER-2 was amplified by CISH in 32 cases (57%) while 33 (59%) were HER-2-positive by IHC. A concordance between HER-2 status determined by CISH and IHC was noted in 43 of 56 cases (77%; P = 0.00008). Gene amplification was observed in 6/16 cases (37.5%) in IHC-negative subgroup (1+), while no amplification was observed in 5/10 cases (50%) in the IHC-positive subgroup (2+). These results suggest that there was a greater heterogeneity on the genetic level and that simple IHC classification was not sufficient. It is suggested that CISH could be considered as a useful additional method to IHC in determining HER-2 status in breast cancer patients, with a recommendation for testing not only the 2+ but also the 1+ subgroup of patients.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Female
  • Humans
  • Immunohistochemistry
  • In Situ Hybridization / methods
  • Receptor, ErbB-2 / analysis*
  • Receptor, ErbB-2 / genetics


  • Receptor, ErbB-2