[Becky]

I too am ER+ but PR neg. The problem with that, in the olden days, is that they did not know that if ER+ but PR neg, something else is going on with the tumor. ER does not get excited (to reproduce the cell) by itself. It likes another playmate (of which PR+ status does). So, if ER is + but PR is negative, who is ER playing with (or what's exciting it)? In our case, it is Her2 receptors. They will excite anything and they also will excite themselves. Hence, resistance due to Her2 positivity. If you were not also Her2 but only ER+, it would be troublesome.

There are also other theories. Some research has been done on the ERPR relationship and when they look at the tumor biochemically most ER+PR+ and ER-PR- tumors look the same but some ER+PR+ tumors actually look like ER-PR- tumors chemically/molecularly. Like they have too many receptors but perhaps they don't work. Vice versa is true too that an ER-PR- could behave as a hormone positive one. They did not take Her2 into account in this study. In this study ER+PR- could be either OR some were totally different (but only a few) and those are categorized as ER+PR-. What does this mean? Well, only if you get the tumor highly analyzed which is only available in a study do you really know and this may be why some tumors are resistant - they are actually behaving as a ER-PR- tumor and not a positive one. I really hope I am making some sense here.

There are also studies that show that blocking ER and Her2 simultaneously is the right way to go.

I will say that being ER+PR- myself, I am still here going on 8 years. I am still on Arimidex alone and did a year with Tamoxifen or Arimidex with Herceptin may have done something good or maybe just the chemo alone did it. I will never know for sure (and I had a node involved). It is a hard decision to make. Like you, I read the studies and got my ovaries removed to use Arimidex (I was 46 at the time). Since you are still on chemo, you have time to ponder, ask questions and come up with a plan you think is right for you.