herceptin and tamoxifen

I am receiving "late" herceptin and have been on tamoxifen for a couple of months. I know there is some question about being her2+ and taking tamoxifen. Not too long ago there was a link on this site for an article addressing herceptin and tamoxifen. However, when I read it my understanding was that the herceptin may actually help tamoxifen do it's job. Am I way off base?
For those of you who have oncs that sidestep the tamoxifen, can you tell me why? I am 46, was premeno prior to chemo, and haven't had a period since Sept. I want to have an educated discussion with my onc about this next week. Can anybody recommend any articles?

I can't recommend any articles but I've had two different breast cancers. For the first one about 14 years ago, they didn't do tests for her2. I took tamox for five years. It obviously didn't work because I got a bilateral cancer on the other side, not a recurrence. The first cancer was premen, the second postmen. I have been on herceptin for a year and am now taking femara. Both tumors were estrogen positive. Hope this helps a little. The new drugs like femara are supposedly much better drugs than tamoxifen. I don't think there's any problem taking any of the drugs with herceptin as it's a totally different mode of action.

A great site for more info is www.breastcancer.org


mts

Here's how I understand it:
Because of cross-talk between HER2 and Estrogen receptors, the body develops tam. resistance. This can be reversed with a tyrosine kinase inhibitor such as Lapatinib or Iressa. There is also a theory that Herceptin + tam. may actually make the cancer wworse but the jury is still out on that one. I would get something to shut down your ovaries and go with the A.I. such as arimidex...that has a proven level of effacy far greater than tam + herceptin.
Regards,
Al

Tamoxfen is only effective if your pathology is ER/PR positive. If you are ER/PR negative, then it doesn't make any sense to take Tamoxifen. The only exception is if you think there is a chance that a future recurrance could have a diifferent pathology, meaning it could be ER/PR positive. But there isn't much data out there to substantiate that probability. My hunch is that we are more likely to get a recurrance that is also Her2 positive, but there are certainly cases out there that go against that.

Some people who have Her2 positive tumors are ER/PR positive and others are ER/PR negative.

Val