HER2 negative now HER2 positive

@Unicornkisses thank you for the information about the website and booklet from www.breastcancer.org

As primek says biopsies are indicative but not always perfect. My changed position (tumour to node) was the post operative advice which is much more reliable.

Not very reassuring, is it @Willow26 just when you are trying to trust your specialists and their recommendations for your best treatment, to have uncertainties arise.
I hope you can get the answers you need to feel confident going forward, if not, keep asking.

The original core biopsies we analysed using IHC and FISH and were checked again with my surgery results.  From what I am hearing the change with HER2 status is not very common.

I had an ER pos result on my core biopsy at 90%.  Then after my surgery they said I was ER neg. No explanation given was satisfactory.  

My tumour was HER2 negative but my one malignant node was positive. It can and does shift. I had a mastectomy, axillary clearance and of course herceptin. Apart from the 12 month bit, I had no problem with herceptin, best wishes for your treatment.

The biopsy from my initial diagnosis came back undecided, it was apparently in the middle so borderline for both. This then required an ISH test which came back negative. Apparently the ISH tests are more accurate. 
After my surgeries my pathology came back -ve, I had ISH tests in both those.

On your pathology results there should be some figures and an explanation of what values determine whether +ve or -ve, they may help you understand.
I believe too that different laboratories can have slightly different perameters for deciding the HER value, but I am guessing that would only change it if you were close to the undecided value.

If you don't have copies of your pathology results, ask your surgeon or GP to print them out for you, you can then have a good look at them.
There is an excellent booklet you can download from www.breast cancer.org the main breast cancer site in the USA, it has a very detailed description of all the pathology results and what they mean, and spaces for you to write in your own.

Whilst my biopsy results didn't change my pathology it did change my grade. My cancer was a grade 3 not 2 as my biopsies had shown. A biopsy takes just a small part of the tumour. Herceptin isn't as difficult to tolerate as chemo is. You will probably have to have a couple of rounds of a taxane type chemo with it initially even if for 1 or 2 doses. Hopefully the auxiliary clearance will find no more nodes or very few. Know that chemo is very effective on her2 cancers and even though a delay it would have kept it at bay. The next part will starve any possible stray cells off. I can imagine the thought of more treatment feels overwhelming but for most women radiotherapy is tolerated well and herceptin certainly allows recovery to continue and you will start feeling quite normal again. Whilst I had heart issues with herceptin, once chemo was done I did feel heaps better and was back working and just popped down and had my dose during the day without issues. 

The frustrating thing is the changing plans and I get that. One of the first things I accepted is we aren't in control of the course our cancer and treatment take. We can make informed choice but when things alter we have to sccept the plan will too. My herceptin was stopped at number 11. It was very upsetting for me and I was scared what that would mean. I came to terms with the change. I focussed on what they said. "Your cancer has been removed. You had response to chemo. You had 6 months of herceptin." I eventually accepted these as okay and with the concern..."we don't want the treatment to cause permanent damage." I get that now. But at the time I was devastated and angy I wasn't in control of the decision. 

It's easy to feel angry and feel the Drs incompetent that the pathology is different. They will be  frustrated and angry as you are,  but less of the emotional response we have of course. But this is why the cancers are sent to pathology again. 

So trust in your team. And take care. You still have a road ahead and we are here for you. Kath x

Our biopsies can be different to our surgery results.
I know others will have more to discuss re Her2 status. Im not her2

Want to encourage you to ask questions, everyone here is supportive and will answer your questions with honesty and support.

Hugs Soldiercrab