We read with great interest the article by Ainsworth et al¹, entitled “IHC for Her2 with CBE356 antibody is a more accurate predictor of Her2 gene amplification by FISH than HercepTest™ in breast carcinoma”. The authors compared immunohistochemical staining for Her2 with the CBE356 antibody with the HercepTest and found that CBE356 provides a cheaper, more accurate predictor of Her2 overexpression than the HercepTest. Our current examinations are similar to their approach, but our opinion differs from that of the authors in several ways.

Correct testing for Her2/neu overexpression and gene amplification is essential to select those, but only those, patients who would benefit from Herceptin treatment. Immunohistochemistry tends to be the chosen method for preliminary screening, mainly because of the ease of performance and low cost. Nevertheless, fluorescence in situ hybridisation (FISH) is the most reliable technique for predicting response to Herceptin treatment.² FISH, however, is considered to …