HER2 is a gene that can influence how a breast cancer behaves and how it might respond to a specific treatment. My biopsy was tested at my local hospital using the IHC test (ImmunoHistoChemistry) and they found that it was HER2 equivocal meaning that a positive or negative result could not be determined. According to Breastcancer.org, the results of this test can be classified as follows:
0 (negative)
1+ (also negative)
2+ (borderline)
3+ (positive — HER2 protein overexpression)
I was 1+ so for confirmation, the sample was then sent out to another hospital for the FISH test (Fluorescence In Situ Hybridization) to be performed as it is a more definitive test where the results can only be positive or negative. The results were negative so it was determined that I would not need Herceptin which is an antibody that targets the HER2 receptor.
The problem with this approach is that if a patient's results are 1+ or 2+, it means their cancer did have some form of HER2 overexpression but the hospital's guidelines say that is not enough to warrant getting Herceptin. My concern like many others is that if there are even just a few cells that could respond to Herceptin, why wouldn't you treat them? It is also possible that depending on where cells are located, the tissue from one area of a breast cancer can test HER2-negative and tissue from a different area can test HER2-positive.
This article goes along the same line of thinking and clearly states that "breast cancer tumors that are human epidermal growth factor receptor 2 (HER2)-negative can spontaneously flip, with populations of circulating HER2-positive cells, according to a new study." It goes on to say that "the ability of these two populations of tumor cells to convert back and forth highlights the importance of treating tumors with drugs that would simultaneously target both populations."
The good thing is that even though I did not qualify for Herceptin at home, the Hallwang clinic was able to target any HER2 positive cells with the use of a peptide vaccine. It is a subcutaneous injection that is given in the abdomen for 5 days then requires a boost every few months. For anyone that is reading this and had a result of 1+ or 2+ on the IHC test, it might be something worth looking into or asking your doctor about. There is no harm in questioning the "standard of care"!