Genes contain the recipes for the various proteins a cell needs to stay healthy and function normally. Some genes and the proteins they make can influence how a breast cancer behaves and how it might respond to a specific treatment.
In addition to results for HER2 gene testing, your pathology report may include information about the status of the EGFR (Epidermal Growth Factor Receptor) gene, sometimes known as the HER1 gene.
As with the HER2 gene, there can be too many copies of the EGFR gene in some breast cancer cells — known as EGFR amplification — which affects how the cancer cells behave. While EGFR amplification testing is not regularly done, some doctors are starting to request it on breast cancer tissue samples. Possible results are “EGFR-positive,” “EGFR-negative,” or “undetermined.”
Other EGFR-positive cancers, such as colon cancer, respond to medicines that target EGFR-positive cancers. Doctors are studying whether these targeted medicines could be used to treat EGFR-positive breast cancer.