What does a breast cancer tumor consist of?

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coffeelatte
coffeelatte Member Posts: 209
edited November 2014 in DCIS (Ductal Carcinoma In Situ)


I was not sure where to post my question.  I had posted it on another thread but I did not get a response. I had read on another thread something a fellow member wrote, "Think about it. If your tumor is, say, 60% er+, then it's 40% er-. That means 40% of the cells in the tumor are er-."

I had never thought about it in that way before.  I guess I thought if your tumor was 60% ER+, then the rest of the tumor was made up of the progesterone receptors and Her2 receptor tissue and/or other tissue.  So does this mean a breast cancer tumor is always 100% cancer and not other tissue?  Does it mean if someone is 60% ER+ then they also have ER- breast cancer too?  I am very confused and would appreciate some help with this.  Thanks.

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  • labelle
    labelle Member Posts: 721
    edited November 2014

    My understanding that your er-/+ is not a percentage of what your cancer cells are made of, but measures how strongly they are responding to estrogen or progesterone. It's what feeds them. Highly ER+ cancers can be starved out (for lack of better words) by cutting off their estrogen supply, or so that is the theory behind hormone therapies (a very simplified version). If a cancer is ER- then it won't respond to cutting of the estrogen supply. Maybe someone else can explain this better but that's the best I can do for now.

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  • april485
    april485 Member Posts: 3,257
    edited November 2014

    From all that I have read, labelle is correct. It is hormone fed but not made up of estrogen or lack thereof. So, it is not negative or positive but is a percentage hormone fed (this is what makes them live and grow from what I understand) which is why they starve them of this hormone if your tumor is found to be responsive to estrogen/progesterone/androgens. Hope that helps!

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  • SpecialK
    SpecialK Member Posts: 16,486
    edited November 2014

    The percentage number you receive on path reports represents the number of cells out of 100 that stain positive for receptors - that is different from the cell itself.  So if they look at the 100 cells under the microscope, and 60 out of the hundred stain, you are 60% ER+.  Same principle applies to PR.  For Her2 they look for an overexpression - everyone has Her2, but some of us have a mutation that causes an abundance of the protein.  This is what is measured by several different testing methods - how much of that protein is present.

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  • coffeelatte
    coffeelatte Member Posts: 209
    edited November 2014

    Thank you so much for the replies. It has really helped clear it up for me.  This came up on another thread because an initial breast cancer tumor was one type, say ER+/PR+, HER2-, but then the original breast cancer metastasized but was biopsied at the new site and found to be ER+/PR-.  It raised the discussion that it is important to have metastasized breast cancer lesions biopsied because they might not always be the same status as the original tumor.  I wonder how it can change like that.  Maybe just the PR- cells were the ones to metastasize or something. So strange to think it could change like that.

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