More understanding of HER2neu testing

Since I was told I was HER2 negative I haven't read that much about it but, now that it is possibly back on the table I've gone and read like crazy which means now I want to educated others!

So here is a better explanation. HER2 is a gene that is found in all breast cells in a pair. These genes put out receptors on the surface of the cell that take in information that tell it to do things like grow. In a breast cancer cell that is considered to be HER2 positive there a more than a pair of these genes and they put up a ton of receptors. On a normal breast cell there is about 20 thousand on a breast cancer cell that is HER2 positive there can be 2 million. So when these receptors pick up the signal (from our bodies somehow) to grow....well you get the picture the cancer goes crazy and makes for a very aggressive cancer (think rabbit ears vs HDTV). So here is a break down of the tests:

IHC-staining-these receptors pump out a certain protein so to test they stain the cancer for this protein and "look" and "score" what they see. If there is a normal amount of protein, negative, tons of protein positive but if you fall in the middle like I did, well they are not sure.

FISH-this test looks internally at the cell and counts how many HER2 gene pairs there are. Too many and it's positive, not too many and it's negative and that is what I've been told. Twice that it is negative. Oh wait make that three times now.

HERmark-the test Dr. Barth is running (at least I'm pretty sure he didn't say the name but, he explained it and I'm 99% sure this is it) this test actually counts the number of the receptors on the cell surface and determines if Herceptin (correct spelling this time) is going to help or not. How? herceptin works by binding to these receptors and telling antibodies in your body to come and kill kill kill. But if there is not a lot of receptors on the cell surface then the herceptin would not do any good. So this test not only tells if you are positive or not but if you are going to benefit from taking herceptin. AND of course there are side effects from herceptin including an increase chance of heart problems so do not take unless you really need to.

OK at least I feel that I have a better understanding of what is going on.