Tissue Microarray Is a Reliable Tool for the Evaluation of HER2 Amplification in Breast Cancer.

AIM: We examined an economical method for evaluating the amplification of the human epidermal growth factor receptor 2 (HER2) gene in breast cancer specimens.

MATERIALS AND METHODS: We compared HER2 amplification determined by fluorescence in situ hybridization (FISH) on whole-tissue (WT) blocks used for diagnostic and on tissue microarray (TMA) sections for a cohort of 521 consecutive patients with breast cancer. In a subset of 116 patients, we examined HER2 concordance from the WT section and a TMA section from a randomly chosen additional block (a proxy of the core biopsy).

RESULTS: Overall concordance for HER2 amplification between WT and TMA sections was 98.2%, and between sections from WT and from the additional block was 99.0%.

CONCLUSION: The high concordance rates support the use of TMA for the evaluation of HER2 amplification in breast cancer and suggest that FISH can be used to assess HER2 using core biopsies.