Tamoxifen and HER2

[Linda in Calif.]

Hi Everyone: I was doing some research about a new drug, GSK572016 and stumbled across this. It was from dukemednews out of Duke University. And I quote, "Surprisingly, however, tamoxifen's cascade of cellular changes leads to other developments within the cancer cells. Blackwell's study showed that tamoxifen resistance actually causes breast cells to increase their production of another growth-regulating receptor protein, called HER2."
Now, I was wondering....does this mean tamoxifen actually increases HER2 production in the breast cells eventually? And if so, how will that effect me who is her2+++ already? Should I be taking Tamoxifen (as I am now)? Have I totally misinterpreted what the article reported? If anyone can clarify this for me I would be very grateful. Take Care, Linda

[Linda in TX]

Hi Linda,
I, too, had read about Blackwell's study while on tamoxifen. I was dx'd as er/pr+ on my original dx in April, 2001...only to discover another isolated tumor that was er/pr- when they went back in to clear the margins after the lumpectomy. At that point it was a bit "controversial"...was I - or +? My onc's decided that since the orig tumor was definately + that I should go on the tamoxifen, which I did for just over a year when I discovered a local recurrence in the same breast (2 years after orig dx). Further scans, etc. revealed a 7cm lesion on my liver (reduced after only 3 rounds of taxotere/herceptin to 3cm!). The recurrent bc also tested er/pr-...I was immediately taken off tamoxifen. I, too, have this theory that the tamoxifen was a culprit in my recurrence...but, of course, who knows really. I'm always looking for the reason "why", as I guess we all do. Have you discussed with your onc the possibility of putting you on one of the inhibitors instead of tamoxifen? I remember mine telling me that it was "unusual" to be her2+ AND er/pr+...I think they are still learning as we go, as far as the her2 thing is concerned. Best of luck to you!!

[Bevie]

Hi Linda I read that as well. After taking Tamoxifen for 8 months with side effects I had the onc switch me to Arimidex which I have been taking for a little over a year with very little side effects and no recurrence so far.

[linda in Calif]

Hi Bevie: What were your side effects? Linda

[wiesia]

Linda,

the way I read it, it means that the cancer cells that become resistant to tamoxifen would tend to be Her2+. I do not think it implies anything about your current Her2+ cells. I also
do not think that it implies anything about recurrence besides the fact that tamoxifen may become ineffective on some part of your cancer cells.

I wonder about Arimidex: do the cancer cells also mutate to "defend" themselves from that drug ?

wiesia

[Jackie]

Hi Linda,
I developed blood clots with Tamoxifen w/in 30 days and was put on Femara, which is another hormonal type drug you could ask your onc about. While I did have a recurrence 1 1/2 yrs later, I think there was a good possibility that I had some metastatic cell activity before even starting on the Femara that just didn't show up on scans (onc ran CA27/29 for unknown reason which showed slightly elevated count). I had hot flashes while on Femara, but not as bad as what you described. Hope you get some good answers to your questions on Mon!
Take care,
Jackie