HER2-FISH, Breast Cancer

The Human Epidermal Growth Factor Receptor 2 (HER2) is a central biomarker in invasive breast cancer, and the HER2 status has both important prognostic implications, and is predictive for the patient’s response to HER2-targeted treatment. According to the guidelines of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP), the HER2 status must be determined by genetic and/or protein expression analysis of breast tissue sections using immunohistochemistry (IHC) and/or in situ hybridization (ISH), respectively, see [1].

To determine the HER2/CEN-17 ratio, the total number of HER2 signals (Red) and the number of CEN-17 (Green) signals in the same 20 nuclei are identified. The total number of HER2 signals is then divided by the number of CEN-17 signals. Ratios above 2 are classified as amplified whereas ratios below 2 are classified un-amplified. Caution should be taken when results are near the cut-off (1.8 – 2.2).
The operator only needs to define an overall region of interest.

Figure 1

Nuclei with amplified gene signals

Figure 2

Detected nuclei and gene signals, invalid nuclei (DAPI signal) are colored in yellow

Figure 3

Nuclei with non-amplified gene signals

Figure 4

Detected nuclei and gene signals

Details

Quantitative Output variables

Four outputs are obtained from this protocol:

Red signal: The total number of red probe signals
Green signal: The total number of green probe signals
Nuclei: The total number of nuclei
Amplification R-G: Amplification level, calculated as the red signals divided by the green signals.

References

LITERATURE
1. Wolff, A.C. et. al., American Society of Clinical Oncology/College of American Pathologists guideline recommendations for Human Epidermal GrowthFactor Receptor 2 Testing in Breast Cancer, J. Clin Oncol 2007, 25 (1), 118-45, DOI