What's the difference between HER2 and HER3

[europa]

I asked my oncologist if I was HER2 or HER3 and she said I was HER2 and that there is no clinical diagnosis for HER3. Hmmmmm. Really?

What is the difference? What determines if you are HER2 or HER3...is it the FISH test?

[greenacres]

Hi there! There is not Her3. Her2 can be amplified up to 3x - so for example, I am Her2+++ which means highly positive and would be a Grade 3. I hope that makes sense. Some people are Her2+, Her2++ and Her2+++, it just all depends on the results of the bloodwork.

[rhondalea]

Really?

The fast answer is "they're not quite there yet." Genentech has some information about HER3 (and HER4) here:

http://www.biooncology.com/research-education/her/her3/index.html

[hutchibk]

As rhondalea said, that pathway (her3) is still under a lot of research and not ready for primetime. Lots of people have been working on it, and we've heard Dr. Osbourne talk about researching it at SABCS...

[chrisy]

Her2
Is part of a family of growth factors which send signals to the call to grow. In her2positive cancer, the cancer cells basically have too many copies of the Her2.

There are 4 members of the family - Her 1,2,3 and 4. So Her2 is a relative of Her3. Like all families, they talk to each other. It's not fully known how communication within that family works, and which relationships are most important in terms of cancer growth, but there is much research going on in this area.

The talks Brenda references by Dr Osborne are built on research that, in test tubes and mice anyway, blocking ALL the growth pathways ( including the Her family as well as some other known pathways) would effectively shut down the cancer. Hurry up on that one, please!

[NEDenise]

Chris,
What an eloquent and clear explanation! You would make a fine teacher! (High praise, coming from me I assure you!)

Always thinking of you...and praying like crazy for NED to find you soon...
Denise

[europa]

Thank you for the explanation. Well, looks like I'm Her2 +++. And now I'm back to being so scared. From everything I've read online HER2+++ tends to be the one that is resistant to Herceptin. I'm so scared that Herceptin won't work on me and that this will come back with a vengeance. I am a single mom to a toddler and cannot even process the thought of him not remembering who his mommy was.

[tricia keegan]

Europa I also was her2+++ and dx seven years ago, so far Herceptin or Arimidex or both have worked for me and most of what you read online is outdated info and pre herceptin so do stick to searching here or asking questions and do remain positive and enjoy life rather than waiting for the other shoe to fall!! (it may hopefully never happen!!):)

[europa]

Thank you so much for your replies. I just get these horrible periods of fear.

[Pray]

Europa, I think we all still have moments of horrible fear (some are far and few between). As you see with my sig. stage 3a her2+++ and have yet to recur. (Thank God!) All though I'm am quite a few tads older as time goes on life will keep taking up more of your time so fear has to step a side. Gods blessings to you sweet little mother.

[europa]

Thank you PRAY. I think I'm going to be a mess until my first MRI post treatment which is October 5th.

[Mtngrl]

I echo the advice not to read too much into little plus signs or people's prognostications. My mantra is "don't worry about anything until you have to." It saves a lot of wear and tear on the psyche.

[KsGal]

I also am her2+++, and I am not Herceptin resistant so far (knock on wood). I read so much online that really scared me....so I quit reading it. Im stable now, and I feel perfectly fine, so I am just going on assuming I AM fine. I know how scary it is...Im still waiting for the day to come when this stupid cancer does not cross my mind and I am a year out from diagnosis. We really don't have a choice except to just keeping marching forward, and it sure is a difficult task sometimes....Know that we are all here for you and praying for you. Big hugs to you.