Benefit of Tamoxifen for ER positive but PR negative

I am on tamoxifen and had 5-10% receptors with moderate staining, so possibly a 3/8 or 4/8 on Allred (although I've never been told.) My PR was negative. I consulted with 3 oncologists and two strongly felt I should be on tamoxifen. They plan to keep me on it for 5 years then 5 years of an AI. It's hard to sort out the information out there but from my research, I found some support for tamoxifen for such low levels.

I thought tamox (and other SERMs) block the estrogen receptors, so I'm not sure why the PR status would matter. (but I'm no doctor). Did your MO have an opinion about the article? (I'd be curious to see if myself, if you want to post a link). If you have questions about your MOs opinion, maybe seek a second opinion?

my wife is also ER + / PR - .  Her OM suggested she falls into the luminal B sub type of be breast cancer, even though she was never tested for ki67 which, I understand, is the marker for luminal B, not PR status.  In any event, I too have read articles suggesting tamoxifen might be inneffective against this sub type, or PR negative cancers.  So the question I have is why bother risking the side effects if it's inneffective to begin with.  Curious to see if any posters here have anything to update on the subject.

Justchapter

Thanks for responding to my message.  Probably best to keep this on the boards for all to see.  I follow what you are saying regarding doing all you can to combat the cancer and just said to my wife this AM that she might as well start taking it.  We sort of concluded between us that the the luminal B subtype potentially stemmed from a Luminal A tumor (theoretically) and so taking the tamoxifen would protect her remaining breast from a recurrence threat.  Again, theoretically.   It would be nice to know, simply from a quality of life, standpoint, if tamoxifen is indeed ineffective.  

I am also reading about other markers in Luminal B cancers (PI3K, mTOR, AKT) on which newer or perhaps existing medicines might be used. I read an article on Afinitor (Everolimus is the active drug), once such drug, but it appears to be used in HER2 + or even post menopause situations.  All very difficult to sift through the literature on all this and, it appears, a lot of literature is based on post menopausal women.

I am intrigued to hear what your F/U (what is an F/U anyway?) has to say on this as, like you inferred, we do not get to see our OM for another 3 months.  I could always arrange a visit sooner, but we are kind of accepting the tamoxifen at present.

Finally, interested to learn if you take the generic or brand name Tamoxifen.  My wife got the generic stuff - just says TEVA Tamoxifen.  Not sure if TEVA is the manufacturer.  Probably means take once a day.

Thanks for responding

T

Just a quick clarification, WifeWBC:  Tamoxifen is meant to protect from recurrence of the original tumor anywhere in the body, not only (and usually not) the remaining breast.  As far as I know, it does not protect against a new tumor forming

theresa45 is correct. Tamoxifen is also given as a preventative. I'm BRCA1+ and even though I had Triple Negative, my MO discussed Tamoxifen with me as a possibility for part of my high-risk management after treatment ended. We ultimately decided against it. She said that if I were BRCA2+, and thus had a higher risk of future hormone positive cancers, she'd push harder for it as a preventative.