***AlaskaAngel****

[Rozebud]

"Rozebud, what I've seen about the minority who are ER-, PR+ is speculation that partly because that group is small, possibly it is due to errors in testing. "

Curious - what have you seen, speculation or otherwise? Thanks - Rose

Because I am not personally ER-/PR+, I mentally filed the information as an interesting note but didn't save articles about it, so today I went on safari on the net to see if I could answer your question (and save face!) My recall is that I saw it mentioned more than once as a possible reason why that group is so small.

How small is it? Well, in one recent study of 1,153 cases the percentage that were ER-/PR+ was 7%. In another study, only one of 942 patients had an ER–/PR+ tumor (0.1%).

(A side note: As a hunter on safari, perhaps one should always take pictures of interesting animals even if one doesn't plan to shoot them. I kept looking.)

I think the following could possibly have been the basis for the in-passing memory that I have:

"A small number of breast cancers are found to be ER negative, PR positive; some of these respond to endocrine therapy. This observation is difficult to reconcile with the accepted view that PR synthesis depends on estrogen action. However, it has been reported that many such tumors, especially in premenopausal patients, actually do contain estrogen receptors that are not detected by steroid-binding assay unless the cytosol is first treated with charcoal."

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?...d.section.12459

Book titled: Cancer Medicine, 6th ed.

[Rozebud]

Interesting - thanks. I'm not completely sure I understood what that article was saying - it was a bit complex for me!! I do know it's pretty rare, in fact, I had read some articles saying that they were thinking of ditching the PR testing since ER-PR+ was so rare - good thing for me they didn't.

Do you know what endocrine therapy is? Not sure I followed from the article....

Well, that is what I like so much about this forum. It is such a fine place to find somebody who might at least have some clues. I read quite a few of the articles about ditching PR testing too and thought that turned out to be a pretty healthy discussion. Even though I am not ER-/PR+, testing is of benefit to me too.

Endocrine therapy in bc conversations refers to the use of treatments for bc such as the anti-estrogens (SERMs like tamoxifen or raloxifene, or AI's like Arimidex, Femara, and Aromasin). But "endocrine therapy" also is treatment like Synthroid for thyroid problems, insulin for diabetes, and even estrogen replacement. So basically "endocrine therapy" is a broad term and is something that is done to manipulate hormonal glands to do something that doctors want it to do.

(Whatever became of the population of genuine guinea pigs is what I want to know?)

What happened was that some people with bc who tested out as ER-/PR+ were showing some benefit from tamoxifen and scientists were puzzled, since theoretically those who are ER- wouldn't benefit from tamoxifen (and as we know, usually anyone who is ER- is also PR-). According to the source I found, they discovered that if the test for PR isn't strictly done by treating they cytosol with charcoal first as one step of the testing, then it wouldn't be accurate. In that case, tumors that actually do have some amount of estrogen would end up being incorrectly classified as being ER-. So I think that is why anyone who is PR+ is likely to be given endocrine therapy.

I wonder if there are actually any ER-/PR+. I wonder if those who are classified as ER-/PR+ and don't respond to tamoxifen happen to also be HER1-positive or HER2-positive, since being HER2 can not only mean tamoxifen doesn't work, but can work against those who are.

Keep asking questions... I do.

AlaskaAngel

[Rozebud]

Thanks - I appreciate it! Actually, everyone I know in that category IS also her2+. Two of us were pregnant at the time. Wondering if there's a relationship there as well. (I can't imagine having breast cancer growing while you're pregnant and NOT being hormone positive...)